diff --git a/src/pkg/reflect/all_test.go b/src/pkg/reflect/all_test.go
index f616ada..bc91576 100644
--- a/src/pkg/reflect/all_test.go
+++ b/src/pkg/reflect/all_test.go
@@ -207,58 +207,46 @@
 
 func TestTypes(t *testing.T) {
 	for i, tt := range typeTests {
-		testType(t, i, NewValue(tt.i).(*StructValue).Field(0).Type(), tt.s)
+		testType(t, i, NewValue(tt.i).Field(0).Type(), tt.s)
 	}
 }
 
 func TestSet(t *testing.T) {
 	for i, tt := range valueTests {
 		v := NewValue(tt.i)
-		switch v := v.(type) {
-		case *IntValue:
-			switch v.Type().Kind() {
-			case Int:
-				v.Set(132)
-			case Int8:
-				v.Set(8)
-			case Int16:
-				v.Set(16)
-			case Int32:
-				v.Set(32)
-			case Int64:
-				v.Set(64)
-			}
-		case *UintValue:
-			switch v.Type().Kind() {
-			case Uint:
-				v.Set(132)
-			case Uint8:
-				v.Set(8)
-			case Uint16:
-				v.Set(16)
-			case Uint32:
-				v.Set(32)
-			case Uint64:
-				v.Set(64)
-			}
-		case *FloatValue:
-			switch v.Type().Kind() {
-			case Float32:
-				v.Set(256.25)
-			case Float64:
-				v.Set(512.125)
-			}
-		case *ComplexValue:
-			switch v.Type().Kind() {
-			case Complex64:
-				v.Set(532.125 + 10i)
-			case Complex128:
-				v.Set(564.25 + 1i)
-			}
-		case *StringValue:
-			v.Set("stringy cheese")
-		case *BoolValue:
-			v.Set(true)
+		switch v.Kind() {
+		case Int:
+			v.SetInt(132)
+		case Int8:
+			v.SetInt(8)
+		case Int16:
+			v.SetInt(16)
+		case Int32:
+			v.SetInt(32)
+		case Int64:
+			v.SetInt(64)
+		case Uint:
+			v.SetUint(132)
+		case Uint8:
+			v.SetUint(8)
+		case Uint16:
+			v.SetUint(16)
+		case Uint32:
+			v.SetUint(32)
+		case Uint64:
+			v.SetUint(64)
+		case Float32:
+			v.SetFloat(256.25)
+		case Float64:
+			v.SetFloat(512.125)
+		case Complex64:
+			v.SetComplex(532.125 + 10i)
+		case Complex128:
+			v.SetComplex(564.25 + 1i)
+		case String:
+			v.SetString("stringy cheese")
+		case Bool:
+			v.SetBool(true)
 		}
 		s := valueToString(v)
 		if s != tt.s {
@@ -270,52 +258,39 @@
 func TestSetValue(t *testing.T) {
 	for i, tt := range valueTests {
 		v := NewValue(tt.i)
-		switch v := v.(type) {
-		case *IntValue:
-			switch v.Type().Kind() {
-			case Int:
-				v.SetValue(NewValue(int(132)))
-			case Int8:
-				v.SetValue(NewValue(int8(8)))
-			case Int16:
-				v.SetValue(NewValue(int16(16)))
-			case Int32:
-				v.SetValue(NewValue(int32(32)))
-			case Int64:
-				v.SetValue(NewValue(int64(64)))
-			}
-		case *UintValue:
-			switch v.Type().Kind() {
-			case Uint:
-				v.SetValue(NewValue(uint(132)))
-			case Uint8:
-				v.SetValue(NewValue(uint8(8)))
-			case Uint16:
-				v.SetValue(NewValue(uint16(16)))
-			case Uint32:
-				v.SetValue(NewValue(uint32(32)))
-			case Uint64:
-				v.SetValue(NewValue(uint64(64)))
-			}
-		case *FloatValue:
-			switch v.Type().Kind() {
-			case Float32:
-				v.SetValue(NewValue(float32(256.25)))
-			case Float64:
-				v.SetValue(NewValue(512.125))
-			}
-		case *ComplexValue:
-			switch v.Type().Kind() {
-			case Complex64:
-				v.SetValue(NewValue(complex64(532.125 + 10i)))
-			case Complex128:
-				v.SetValue(NewValue(complex128(564.25 + 1i)))
-			}
-
-		case *StringValue:
-			v.SetValue(NewValue("stringy cheese"))
-		case *BoolValue:
-			v.SetValue(NewValue(true))
+		switch v.Kind() {
+		case Int:
+			v.Set(NewValue(int(132)))
+		case Int8:
+			v.Set(NewValue(int8(8)))
+		case Int16:
+			v.Set(NewValue(int16(16)))
+		case Int32:
+			v.Set(NewValue(int32(32)))
+		case Int64:
+			v.Set(NewValue(int64(64)))
+		case Uint:
+			v.Set(NewValue(uint(132)))
+		case Uint8:
+			v.Set(NewValue(uint8(8)))
+		case Uint16:
+			v.Set(NewValue(uint16(16)))
+		case Uint32:
+			v.Set(NewValue(uint32(32)))
+		case Uint64:
+			v.Set(NewValue(uint64(64)))
+		case Float32:
+			v.Set(NewValue(float32(256.25)))
+		case Float64:
+			v.Set(NewValue(512.125))
+		case Complex64:
+			v.Set(NewValue(complex64(532.125 + 10i)))
+		case Complex128:
+			v.Set(NewValue(complex128(564.25 + 1i)))
+		case String:
+			v.Set(NewValue("stringy cheese"))
+		case Bool:
+			v.Set(NewValue(true))
 		}
 		s := valueToString(v)
 		if s != tt.s {
@@ -350,7 +325,7 @@
 
 func TestArrayElemSet(t *testing.T) {
 	v := NewValue([10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
-	v.(*ArrayValue).Elem(4).(*IntValue).Set(123)
+	v.Index(4).SetInt(123)
 	s := valueToString(v)
 	const want = "[10]int{1, 2, 3, 4, 123, 6, 7, 8, 9, 10}"
 	if s != want {
@@ -358,7 +333,7 @@
 	}
 
 	v = NewValue([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
-	v.(*SliceValue).Elem(4).(*IntValue).Set(123)
+	v.Index(4).SetInt(123)
 	s = valueToString(v)
 	const want1 = "[]int{1, 2, 3, 4, 123, 6, 7, 8, 9, 10}"
 	if s != want1 {
@@ -371,14 +346,14 @@
 	var i int32 = 1234
 	vip := NewValue(&ip)
 	vi := NewValue(i)
-	vip.(*PtrValue).Elem().(*PtrValue).PointTo(vi)
+	vip.Elem().Set(vi.Addr())
 	if *ip != 1234 {
 		t.Errorf("got %d, want 1234", *ip)
 	}
 
 	ip = nil
-	vp := NewValue(ip).(*PtrValue)
-	vp.PointTo(vp.Elem())
+	vp := NewValue(ip)
+	vp.Set(Zero(vp.Type()))
 	if ip != nil {
 		t.Errorf("got non-nil (%p), want nil", ip)
 	}
@@ -388,7 +363,7 @@
 	var i int32 = 1234
 	ip := &i
 	vip := NewValue(&ip)
-	vip.(*PtrValue).Elem().(*PtrValue).Set(nil)
+	vip.Elem().Set(Zero(vip.Elem().Type()))
 	if ip != nil {
 		t.Errorf("got non-nil (%d), want nil", *ip)
 	}
@@ -397,7 +372,7 @@
 func TestMapSetNil(t *testing.T) {
 	m := make(map[string]int)
 	vm := NewValue(&m)
-	vm.(*PtrValue).Elem().(*MapValue).Set(nil)
+	vm.Elem().Set(Zero(vm.Elem().Type()))
 	if m != nil {
 		t.Errorf("got non-nil (%p), want nil", m)
 	}
@@ -406,16 +381,16 @@
 
 func TestAll(t *testing.T) {
 	testType(t, 1, Typeof((int8)(0)), "int8")
-	testType(t, 2, Typeof((*int8)(nil)).(*PtrType).Elem(), "int8")
+	testType(t, 2, Typeof((*int8)(nil)).Elem(), "int8")
 
 	typ := Typeof((*struct {
 		c chan *int32
 		d float32
 	})(nil))
 	testType(t, 3, typ, "*struct { c chan *int32; d float32 }")
-	etyp := typ.(*PtrType).Elem()
+	etyp := typ.Elem()
 	testType(t, 4, etyp, "struct { c chan *int32; d float32 }")
-	styp := etyp.(*StructType)
+	styp := etyp
 	f := styp.Field(0)
 	testType(t, 5, f.Type, "chan *int32")
 
@@ -432,22 +407,22 @@
 
 	typ = Typeof([32]int32{})
 	testType(t, 7, typ, "[32]int32")
-	testType(t, 8, typ.(*ArrayType).Elem(), "int32")
+	testType(t, 8, typ.Elem(), "int32")
 
 	typ = Typeof((map[string]*int32)(nil))
 	testType(t, 9, typ, "map[string] *int32")
-	mtyp := typ.(*MapType)
+	mtyp := typ
 	testType(t, 10, mtyp.Key(), "string")
 	testType(t, 11, mtyp.Elem(), "*int32")
 
 	typ = Typeof((chan<- string)(nil))
 	testType(t, 12, typ, "chan<- string")
-	testType(t, 13, typ.(*ChanType).Elem(), "string")
+	testType(t, 13, typ.Elem(), "string")
 
 	// make sure tag strings are not part of element type
 	typ = Typeof(struct {
 		d []uint32 "TAG"
-	}{}).(*StructType).Field(0).Type
+	}{}).Field(0).Type
 	testType(t, 14, typ, "[]uint32")
 }
 
@@ -457,9 +432,9 @@
 	}
 	inter.e = 123.456
 	v1 := NewValue(&inter)
-	v2 := v1.(*PtrValue).Elem().(*StructValue).Field(0)
+	v2 := v1.Elem().Field(0)
 	assert(t, v2.Type().String(), "interface { }")
-	i2 := v2.(*InterfaceValue).Interface()
+	i2 := v2.Interface()
 	v3 := NewValue(i2)
 	assert(t, v3.Type().String(), "float64")
 }
@@ -470,9 +445,9 @@
 	}
 	inter.e = 123.456
 	v1 := NewValue(&inter)
-	v2 := v1.(*PtrValue).Elem().(*StructValue).Field(0)
+	v2 := v1.Elem().Field(0)
 	assert(t, v2.Type().String(), "interface { }")
-	v3 := v2.(*InterfaceValue).Elem()
+	v3 := v2.Elem()
 	assert(t, v3.Type().String(), "float64")
 
 	i3 := v2.Interface()
@@ -506,9 +481,9 @@
 			e0[j] = NewValue(e)
 		}
 		// Convert extra from []int to *SliceValue.
-		e1 := NewValue(test.extra).(*SliceValue)
+		e1 := NewValue(test.extra)
 		// Test Append.
-		a0 := NewValue(test.orig).(*SliceValue)
+		a0 := NewValue(test.orig)
 		have0 := Append(a0, e0...).Interface().([]int)
 		if !DeepEqual(have0, want) {
 			t.Errorf("Append #%d: have %v, want %v", i, have0, want)
@@ -521,7 +496,7 @@
 			t.Errorf("Append #%d extraLen: have %v, want %v", i, len(test.extra), extraLen)
 		}
 		// Test AppendSlice.
-		a1 := NewValue(test.orig).(*SliceValue)
+		a1 := NewValue(test.orig)
 		have1 := AppendSlice(a1, e1).Interface().([]int)
 		if !DeepEqual(have1, want) {
 			t.Errorf("AppendSlice #%d: have %v, want %v", i, have1, want)
@@ -545,8 +520,8 @@
 			t.Fatalf("b != c before test")
 		}
 	}
-	aa := NewValue(a).(*SliceValue)
-	ab := NewValue(b).(*SliceValue)
+	aa := NewValue(a)
+	ab := NewValue(b)
 	for tocopy := 1; tocopy <= 7; tocopy++ {
 		aa.SetLen(tocopy)
 		Copy(ab, aa)
@@ -660,7 +635,7 @@
 func TestTypeof(t *testing.T) {
 	for _, test := range deepEqualTests {
 		v := NewValue(test.a)
-		if v == nil {
+		if !v.IsValid() {
 			continue
 		}
 		typ := Typeof(test.a)
@@ -715,8 +690,8 @@
 
 
 func check2ndField(x interface{}, offs uintptr, t *testing.T) {
-	s := NewValue(x).(*StructValue)
-	f := s.Type().(*StructType).Field(1)
+	s := NewValue(x)
+	f := s.Type().Field(1)
 	if f.Offset != offs {
 		t.Error("mismatched offsets in structure alignment:", f.Offset, offs)
 	}
@@ -747,36 +722,22 @@
 	check2ndField(x1, uintptr(unsafe.Pointer(&x1.f))-uintptr(unsafe.Pointer(&x1)), t)
 }
 
-type IsNiller interface {
-	IsNil() bool
-}
-
 func Nil(a interface{}, t *testing.T) {
-	n := NewValue(a).(*StructValue).Field(0).(IsNiller)
+	n := NewValue(a).Field(0)
 	if !n.IsNil() {
 		t.Errorf("%v should be nil", a)
 	}
 }
 
 func NotNil(a interface{}, t *testing.T) {
-	n := NewValue(a).(*StructValue).Field(0).(IsNiller)
+	n := NewValue(a).Field(0)
 	if n.IsNil() {
 		t.Errorf("value of type %v should not be nil", NewValue(a).Type().String())
 	}
 }
 
 func TestIsNil(t *testing.T) {
-	// These do not implement IsNil
-	doNotNil := []interface{}{int(0), float32(0), struct{ a int }{}}
-	for _, ts := range doNotNil {
-		ty := Typeof(ts)
-		v := MakeZero(ty)
-		if _, ok := v.(IsNiller); ok {
-			t.Errorf("%s is nilable; should not be", ts)
-		}
-	}
-
-	// These do implement IsNil.
+	// These implement IsNil.
 	// Wrap in extra struct to hide interface type.
 	doNil := []interface{}{
 		struct{ x *int }{},
@@ -787,11 +748,9 @@
 		struct{ x []string }{},
 	}
 	for _, ts := range doNil {
-		ty := Typeof(ts).(*StructType).Field(0).Type
-		v := MakeZero(ty)
-		if _, ok := v.(IsNiller); !ok {
-			t.Errorf("%s %T is not nilable; should be", ts, v)
-		}
+		ty := Typeof(ts).Field(0).Type
+		v := Zero(ty)
+		v.IsNil() // panics if not okay to call
 	}
 
 	// Check the implementations
@@ -844,7 +803,7 @@
 	}
 
 	s.w = os.Stdout
-	v := Indirect(NewValue(&s)).(*StructValue).Field(0).Interface()
+	v := Indirect(NewValue(&s)).Field(0).Interface()
 	if v != s.w.(interface{}) {
 		t.Error("Interface() on interface: ", v, s.w)
 	}
@@ -864,7 +823,7 @@
 
 	// and setting that copy to "bye" should
 	// not change the value stored in i.
-	v.(*StringValue).Set("bye")
+	v.SetString("bye")
 	if i.(string) != "hello" {
 		t.Errorf(`Set("bye") changed i to %s`, i.(string))
 	}
@@ -872,7 +831,7 @@
 	// the same should be true of smaller items.
 	i = 123
 	v = NewValue(i)
-	v.(*IntValue).Set(234)
+	v.SetInt(234)
 	if i.(int) != 123 {
 		t.Errorf("Set(234) changed i to %d", i.(int))
 	}
@@ -880,20 +839,20 @@
 
 func TestNilPtrValueSub(t *testing.T) {
 	var pi *int
-	if pv := NewValue(pi).(*PtrValue); pv.Elem() != nil {
-		t.Error("NewValue((*int)(nil)).(*PtrValue).Elem() != nil")
+	if pv := NewValue(pi); pv.Elem().IsValid() {
+		t.Error("NewValue((*int)(nil)).Elem().IsValid()")
 	}
 }
 
 func TestMap(t *testing.T) {
 	m := map[string]int{"a": 1, "b": 2}
-	mv := NewValue(m).(*MapValue)
+	mv := NewValue(m)
 	if n := mv.Len(); n != len(m) {
 		t.Errorf("Len = %d, want %d", n, len(m))
 	}
-	keys := mv.Keys()
+	keys := mv.MapKeys()
 	i := 0
-	newmap := MakeMap(mv.Type().(*MapType))
+	newmap := MakeMap(mv.Type())
 	for k, v := range m {
 		// Check that returned Keys match keys in range.
 		// These aren't required to be in the same order,
@@ -901,22 +860,22 @@
 		// the test easier.
 		if i >= len(keys) {
 			t.Errorf("Missing key #%d %q", i, k)
-		} else if kv := keys[i].(*StringValue); kv.Get() != k {
-			t.Errorf("Keys[%d] = %q, want %q", i, kv.Get(), k)
+		} else if kv := keys[i]; kv.String() != k {
+			t.Errorf("Keys[%q] = %d, want %d", i, kv.Int(), k)
 		}
 		i++
 
 		// Check that value lookup is correct.
-		vv := mv.Elem(NewValue(k))
-		if vi := vv.(*IntValue).Get(); vi != int64(v) {
+		vv := mv.MapIndex(NewValue(k))
+		if vi := vv.Int(); vi != int64(v) {
 			t.Errorf("Key %q: have value %d, want %d", k, vi, v)
 		}
 
 		// Copy into new map.
-		newmap.SetElem(NewValue(k), NewValue(v))
+		newmap.SetMapIndex(NewValue(k), NewValue(v))
 	}
-	vv := mv.Elem(NewValue("not-present"))
-	if vv != nil {
+	vv := mv.MapIndex(NewValue("not-present"))
+	if vv.IsValid() {
 		t.Errorf("Invalid key: got non-nil value %s", valueToString(vv))
 	}
 
@@ -932,14 +891,14 @@
 		}
 	}
 
-	newmap.SetElem(NewValue("a"), nil)
+	newmap.SetMapIndex(NewValue("a"), Value{})
 	v, ok := newm["a"]
 	if ok {
 		t.Errorf("newm[\"a\"] = %d after delete", v)
 	}
 
-	mv = NewValue(&m).(*PtrValue).Elem().(*MapValue)
-	mv.Set(nil)
+	mv = NewValue(&m).Elem()
+	mv.Set(Zero(mv.Type()))
 	if m != nil {
 		t.Errorf("mv.Set(nil) failed")
 	}
@@ -948,15 +907,15 @@
 func TestChan(t *testing.T) {
 	for loop := 0; loop < 2; loop++ {
 		var c chan int
-		var cv *ChanValue
+		var cv Value
 
 		// check both ways to allocate channels
 		switch loop {
 		case 1:
 			c = make(chan int, 1)
-			cv = NewValue(c).(*ChanValue)
+			cv = NewValue(c)
 		case 0:
-			cv = MakeChan(Typeof(c).(*ChanType), 1)
+			cv = MakeChan(Typeof(c), 1)
 			c = cv.Interface().(chan int)
 		}
 
@@ -968,22 +927,22 @@
 
 		// Recv
 		c <- 3
-		if i, ok := cv.Recv(); i.(*IntValue).Get() != 3 || !ok {
-			t.Errorf("native send 3, reflect Recv %d, %t", i.(*IntValue).Get(), ok)
+		if i, ok := cv.Recv(); i.Int() != 3 || !ok {
+			t.Errorf("native send 3, reflect Recv %d, %t", i.Int(), ok)
 		}
 
 		// TryRecv fail
 		val, ok := cv.TryRecv()
-		if val != nil || ok {
+		if val.IsValid() || ok {
 			t.Errorf("TryRecv on empty chan: %s, %t", valueToString(val), ok)
 		}
 
 		// TryRecv success
 		c <- 4
 		val, ok = cv.TryRecv()
-		if val == nil {
+		if !val.IsValid() {
 			t.Errorf("TryRecv on ready chan got nil")
-		} else if i := val.(*IntValue).Get(); i != 4 || !ok {
+		} else if i := val.Int(); i != 4 || !ok {
 			t.Errorf("native send 4, TryRecv %d, %t", i, ok)
 		}
 
@@ -1008,27 +967,27 @@
 		// Close
 		c <- 123
 		cv.Close()
-		if i, ok := cv.Recv(); i.(*IntValue).Get() != 123 || !ok {
-			t.Errorf("send 123 then close; Recv %d, %t", i.(*IntValue).Get(), ok)
+		if i, ok := cv.Recv(); i.Int() != 123 || !ok {
+			t.Errorf("send 123 then close; Recv %d, %t", i.Int(), ok)
 		}
-		if i, ok := cv.Recv(); i.(*IntValue).Get() != 0 || ok {
-			t.Errorf("after close Recv %d, %t", i.(*IntValue).Get(), ok)
+		if i, ok := cv.Recv(); i.Int() != 0 || ok {
+			t.Errorf("after close Recv %d, %t", i.Int(), ok)
 		}
 	}
 
 	// check creation of unbuffered channel
 	var c chan int
-	cv := MakeChan(Typeof(c).(*ChanType), 0)
+	cv := MakeChan(Typeof(c), 0)
 	c = cv.Interface().(chan int)
 	if cv.TrySend(NewValue(7)) {
 		t.Errorf("TrySend on sync chan succeeded")
 	}
-	if v, ok := cv.TryRecv(); v != nil || ok {
+	if v, ok := cv.TryRecv(); v.IsValid() || ok {
 		t.Errorf("TryRecv on sync chan succeeded")
 	}
 
 	// len/cap
-	cv = MakeChan(Typeof(c).(*ChanType), 10)
+	cv = MakeChan(Typeof(c), 10)
 	c = cv.Interface().(chan int)
 	for i := 0; i < 3; i++ {
 		c <- i
@@ -1046,14 +1005,14 @@
 }
 
 func TestFunc(t *testing.T) {
-	ret := NewValue(dummy).(*FuncValue).Call([]Value{NewValue(byte(10)), NewValue(20), NewValue(byte(30))})
+	ret := NewValue(dummy).Call([]Value{NewValue(byte(10)), NewValue(20), NewValue(byte(30))})
 	if len(ret) != 3 {
 		t.Fatalf("Call returned %d values, want 3", len(ret))
 	}
 
-	i := ret[0].(*UintValue).Get()
-	j := ret[1].(*IntValue).Get()
-	k := ret[2].(*UintValue).Get()
+	i := byte(ret[0].Uint())
+	j := int(ret[1].Int())
+	k := byte(ret[2].Uint())
 	if i != 10 || j != 20 || k != 30 {
 		t.Errorf("Call returned %d, %d, %d; want 10, 20, 30", i, j, k)
 	}
@@ -1068,30 +1027,30 @@
 func TestMethod(t *testing.T) {
 	// Non-curried method of type.
 	p := Point{3, 4}
-	i := Typeof(p).Method(0).Func.Call([]Value{NewValue(p), NewValue(10)})[0].(*IntValue).Get()
+	i := Typeof(p).Method(0).Func.Call([]Value{NewValue(p), NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Type Method returned %d; want 250", i)
 	}
 
-	i = Typeof(&p).Method(0).Func.Call([]Value{NewValue(&p), NewValue(10)})[0].(*IntValue).Get()
+	i = Typeof(&p).Method(0).Func.Call([]Value{NewValue(&p), NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Pointer Type Method returned %d; want 250", i)
 	}
 
 	// Curried method of value.
-	i = NewValue(p).Method(0).Call([]Value{NewValue(10)})[0].(*IntValue).Get()
+	i = NewValue(p).Method(0).Call([]Value{NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Value Method returned %d; want 250", i)
 	}
 
 	// Curried method of pointer.
-	i = NewValue(&p).Method(0).Call([]Value{NewValue(10)})[0].(*IntValue).Get()
+	i = NewValue(&p).Method(0).Call([]Value{NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Value Method returned %d; want 250", i)
 	}
 
 	// Curried method of pointer to value.
-	i = NewValue(p).Addr().Method(0).Call([]Value{NewValue(10)})[0].(*IntValue).Get()
+	i = NewValue(p).Addr().Method(0).Call([]Value{NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Value Method returned %d; want 250", i)
 	}
@@ -1105,8 +1064,8 @@
 			Dist(int) int
 		}
 	}{p}
-	pv := NewValue(s).(*StructValue).Field(0)
-	i = pv.Method(0).Call([]Value{NewValue(10)})[0].(*IntValue).Get()
+	pv := NewValue(s).Field(0)
+	i = pv.Method(0).Call([]Value{NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Interface Method returned %d; want 250", i)
 	}
@@ -1121,19 +1080,19 @@
 			Dist(int) int
 		}
 	}
-	sv := NewValue(&s).(*PtrValue).Elem().(*StructValue)
-	sv.Field(0).(*InterfaceValue).Set(NewValue(p))
+	sv := NewValue(&s).Elem()
+	sv.Field(0).Set(NewValue(p))
 	if q := s.I.(*Point); q != p {
 		t.Errorf("i: have %p want %p", q, p)
 	}
 
-	pv := sv.Field(1).(*InterfaceValue)
+	pv := sv.Field(1)
 	pv.Set(NewValue(p))
 	if q := s.P.(*Point); q != p {
 		t.Errorf("i: have %p want %p", q, p)
 	}
 
-	i := pv.Method(0).Call([]Value{NewValue(10)})[0].(*IntValue).Get()
+	i := pv.Method(0).Call([]Value{NewValue(10)})[0].Int()
 	if i != 250 {
 		t.Errorf("Interface Method returned %d; want 250", i)
 	}
@@ -1148,7 +1107,7 @@
 	var field StructField
 	var ok bool
 	var t1 T1
-	type1 := Typeof(t1).(*StructType)
+	type1 := Typeof(t1)
 	if field, ok = type1.FieldByName("int"); !ok {
 		t.Error("no field 'int'")
 	}
@@ -1232,7 +1191,7 @@
 
 func TestFieldByIndex(t *testing.T) {
 	for _, test := range fieldTests {
-		s := Typeof(test.s).(*StructType)
+		s := Typeof(test.s)
 		f := s.FieldByIndex(test.index)
 		if f.Name != "" {
 			if test.index != nil {
@@ -1247,8 +1206,8 @@
 		}
 
 		if test.value != 0 {
-			v := NewValue(test.s).(*StructValue).FieldByIndex(test.index)
-			if v != nil {
+			v := NewValue(test.s).FieldByIndex(test.index)
+			if v.IsValid() {
 				if x, ok := v.Interface().(int); ok {
 					if x != test.value {
 						t.Errorf("%s%v is %d; want %d", s.Name(), test.index, x, test.value)
@@ -1265,7 +1224,7 @@
 
 func TestFieldByName(t *testing.T) {
 	for _, test := range fieldTests {
-		s := Typeof(test.s).(*StructType)
+		s := Typeof(test.s)
 		f, found := s.FieldByName(test.name)
 		if found {
 			if test.index != nil {
@@ -1287,8 +1246,8 @@
 		}
 
 		if test.value != 0 {
-			v := NewValue(test.s).(*StructValue).FieldByName(test.name)
-			if v != nil {
+			v := NewValue(test.s).FieldByName(test.name)
+			if v.IsValid() {
 				if x, ok := v.Interface().(int); ok {
 					if x != test.value {
 						t.Errorf("%s.%s is %d; want %d", s.Name(), test.name, x, test.value)
@@ -1312,10 +1271,10 @@
 func TestDotDotDot(t *testing.T) {
 	// Test example from FuncType.DotDotDot documentation.
 	var f func(x int, y ...float64)
-	typ := Typeof(f).(*FuncType)
+	typ := Typeof(f)
 	if typ.NumIn() == 2 && typ.In(0) == Typeof(int(0)) {
-		sl, ok := typ.In(1).(*SliceType)
-		if ok {
+		sl := typ.In(1)
+		if sl.Kind() == Slice {
 			if sl.Elem() == Typeof(0.0) {
 				// ok
 				return
@@ -1346,11 +1305,11 @@
 
 func TestNestedMethods(t *testing.T) {
 	typ := Typeof((*outer)(nil))
-	if typ.NumMethod() != 1 || typ.Method(0).Func.Get() != NewValue((*outer).m).(*FuncValue).Get() {
+	if typ.NumMethod() != 1 || typ.Method(0).Func.Pointer() != NewValue((*outer).m).Pointer() {
 		t.Errorf("Wrong method table for outer: (m=%p)", (*outer).m)
 		for i := 0; i < typ.NumMethod(); i++ {
 			m := typ.Method(i)
-			t.Errorf("\t%d: %s %#x\n", i, m.Name, m.Func.Get())
+			t.Errorf("\t%d: %s %#x\n", i, m.Name, m.Func.Pointer())
 		}
 	}
 }
@@ -1370,21 +1329,21 @@
 
 func TestEmbeddedMethods(t *testing.T) {
 	typ := Typeof((*outerInt)(nil))
-	if typ.NumMethod() != 1 || typ.Method(0).Func.Get() != NewValue((*outerInt).m).(*FuncValue).Get() {
+	if typ.NumMethod() != 1 || typ.Method(0).Func.Pointer() != NewValue((*outerInt).m).Pointer() {
 		t.Errorf("Wrong method table for outerInt: (m=%p)", (*outerInt).m)
 		for i := 0; i < typ.NumMethod(); i++ {
 			m := typ.Method(i)
-			t.Errorf("\t%d: %s %#x\n", i, m.Name, m.Func.Get())
+			t.Errorf("\t%d: %s %#x\n", i, m.Name, m.Func.Pointer())
 		}
 	}
 
 	i := &innerInt{3}
-	if v := NewValue(i).Method(0).Call(nil)[0].(*IntValue).Get(); v != 3 {
+	if v := NewValue(i).Method(0).Call(nil)[0].Int(); v != 3 {
 		t.Errorf("i.m() = %d, want 3", v)
 	}
 
 	o := &outerInt{1, innerInt{2}}
-	if v := NewValue(o).Method(0).Call(nil)[0].(*IntValue).Get(); v != 2 {
+	if v := NewValue(o).Method(0).Call(nil)[0].Int(); v != 2 {
 		t.Errorf("i.m() = %d, want 2", v)
 	}
 
@@ -1402,7 +1361,7 @@
 		typ = PtrTo(typ)
 	}
 	for i = 0; i < 100; i++ {
-		typ = typ.(*PtrType).Elem()
+		typ = typ.Elem()
 	}
 	if typ != Typeof(i) {
 		t.Errorf("after 100 PtrTo and Elem, have %s, want %s", typ, Typeof(i))
@@ -1415,11 +1374,11 @@
 	}
 
 	v := NewValue(&p)
-	v = v.(*PtrValue).Elem()
+	v = v.Elem()
 	v = v.Addr()
-	v = v.(*PtrValue).Elem()
-	v = v.(*StructValue).Field(0)
-	v.(*IntValue).Set(2)
+	v = v.Elem()
+	v = v.Field(0)
+	v.SetInt(2)
 	if p.X != 2 {
 		t.Errorf("Addr.Elem.Set failed to set value")
 	}
@@ -1428,12 +1387,12 @@
 	// Exercises generation of PtrTypes not present in the binary.
 	v = NewValue(&p)
 	v = v.Addr()
-	v = v.(*PtrValue).Elem()
-	v = v.(*PtrValue).Elem()
+	v = v.Elem()
+	v = v.Elem()
 	v = v.Addr()
-	v = v.(*PtrValue).Elem()
-	v = v.(*StructValue).Field(0)
-	v.(*IntValue).Set(3)
+	v = v.Elem()
+	v = v.Field(0)
+	v.SetInt(3)
 	if p.X != 3 {
 		t.Errorf("Addr.Elem.Set failed to set value")
 	}
@@ -1443,9 +1402,9 @@
 	v = NewValue(p)
 	v0 := v
 	v = v.Addr()
-	v = v.(*PtrValue).Elem()
-	v = v.(*StructValue).Field(0)
-	v.(*IntValue).Set(4)
+	v = v.Elem()
+	v = v.Field(0)
+	v.SetInt(4)
 	if p.X != 3 { // should be unchanged from last time
 		t.Errorf("somehow value Set changed original p")
 	}
diff --git a/src/pkg/reflect/deepequal.go b/src/pkg/reflect/deepequal.go
index c9beec5..f5a7814 100644
--- a/src/pkg/reflect/deepequal.go
+++ b/src/pkg/reflect/deepequal.go
@@ -22,8 +22,8 @@
 // comparisons that have already been seen, which allows short circuiting on
 // recursive types.
 func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth int) bool {
-	if v1 == nil || v2 == nil {
-		return v1 == v2
+	if !v1.IsValid() || !v2.IsValid() {
+		return v1.IsValid() == v2.IsValid()
 	}
 	if v1.Type() != v2.Type() {
 		return false
@@ -56,57 +56,47 @@
 	// Remember for later.
 	visited[h] = &visit{addr1, addr2, typ, seen}
 
-	switch v := v1.(type) {
-	case *ArrayValue:
-		arr1 := v
-		arr2 := v2.(*ArrayValue)
-		if arr1.Len() != arr2.Len() {
+	switch v1.Kind() {
+	case Array:
+		if v1.Len() != v2.Len() {
 			return false
 		}
-		for i := 0; i < arr1.Len(); i++ {
-			if !deepValueEqual(arr1.Elem(i), arr2.Elem(i), visited, depth+1) {
+		for i := 0; i < v1.Len(); i++ {
+			if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
 				return false
 			}
 		}
 		return true
-	case *SliceValue:
-		arr1 := v
-		arr2 := v2.(*SliceValue)
-		if arr1.Len() != arr2.Len() {
+	case Slice:
+		if v1.Len() != v2.Len() {
 			return false
 		}
-		for i := 0; i < arr1.Len(); i++ {
-			if !deepValueEqual(arr1.Elem(i), arr2.Elem(i), visited, depth+1) {
+		for i := 0; i < v1.Len(); i++ {
+			if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
 				return false
 			}
 		}
 		return true
-	case *InterfaceValue:
-		i1 := v.Interface()
-		i2 := v2.Interface()
-		if i1 == nil || i2 == nil {
-			return i1 == i2
+	case Interface:
+		if v1.IsNil() || v2.IsNil() {
+			return v1.IsNil() == v2.IsNil()
 		}
-		return deepValueEqual(NewValue(i1), NewValue(i2), visited, depth+1)
-	case *PtrValue:
-		return deepValueEqual(v.Elem(), v2.(*PtrValue).Elem(), visited, depth+1)
-	case *StructValue:
-		struct1 := v
-		struct2 := v2.(*StructValue)
-		for i, n := 0, v.NumField(); i < n; i++ {
-			if !deepValueEqual(struct1.Field(i), struct2.Field(i), visited, depth+1) {
+		return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
+	case Ptr:
+		return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
+	case Struct:
+		for i, n := 0, v1.NumField(); i < n; i++ {
+			if !deepValueEqual(v1.Field(i), v2.Field(i), visited, depth+1) {
 				return false
 			}
 		}
 		return true
-	case *MapValue:
-		map1 := v
-		map2 := v2.(*MapValue)
-		if map1.Len() != map2.Len() {
+	case Map:
+		if v1.Len() != v2.Len() {
 			return false
 		}
-		for _, k := range map1.Keys() {
-			if !deepValueEqual(map1.Elem(k), map2.Elem(k), visited, depth+1) {
+		for _, k := range v1.MapKeys() {
+			if !deepValueEqual(v1.MapIndex(k), v2.MapIndex(k), visited, depth+1) {
 				return false
 			}
 		}
diff --git a/src/pkg/reflect/tostring_test.go b/src/pkg/reflect/tostring_test.go
index a1487fd..5f5c52b 100644
--- a/src/pkg/reflect/tostring_test.go
+++ b/src/pkg/reflect/tostring_test.go
@@ -17,29 +17,29 @@
 // For debugging only.
 func valueToString(val Value) string {
 	var str string
-	if val == nil {
-		return "<nil>"
+	if !val.IsValid() {
+		return "<zero Value>"
 	}
 	typ := val.Type()
-	switch val := val.(type) {
-	case *IntValue:
-		return strconv.Itoa64(val.Get())
-	case *UintValue:
-		return strconv.Uitoa64(val.Get())
-	case *FloatValue:
-		return strconv.Ftoa64(float64(val.Get()), 'g', -1)
-	case *ComplexValue:
-		c := val.Get()
-		return strconv.Ftoa64(float64(real(c)), 'g', -1) + "+" + strconv.Ftoa64(float64(imag(c)), 'g', -1) + "i"
-	case *StringValue:
-		return val.Get()
-	case *BoolValue:
-		if val.Get() {
+	switch val.Kind() {
+	case Int, Int8, Int16, Int32, Int64:
+		return strconv.Itoa64(val.Int())
+	case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+		return strconv.Uitoa64(val.Uint())
+	case Float32, Float64:
+		return strconv.Ftoa64(val.Float(), 'g', -1)
+	case Complex64, Complex128:
+		c := val.Complex()
+		return strconv.Ftoa64(real(c), 'g', -1) + "+" + strconv.Ftoa64(imag(c), 'g', -1) + "i"
+	case String:
+		return val.String()
+	case Bool:
+		if val.Bool() {
 			return "true"
 		} else {
 			return "false"
 		}
-	case *PtrValue:
+	case Ptr:
 		v := val
 		str = typ.String() + "("
 		if v.IsNil() {
@@ -49,7 +49,7 @@
 		}
 		str += ")"
 		return str
-	case ArrayOrSliceValue:
+	case Array, Slice:
 		v := val
 		str += typ.String()
 		str += "{"
@@ -57,22 +57,22 @@
 			if i > 0 {
 				str += ", "
 			}
-			str += valueToString(v.Elem(i))
+			str += valueToString(v.Index(i))
 		}
 		str += "}"
 		return str
-	case *MapValue:
-		t := typ.(*MapType)
+	case Map:
+		t := typ
 		str = t.String()
 		str += "{"
 		str += "<can't iterate on maps>"
 		str += "}"
 		return str
-	case *ChanValue:
+	case Chan:
 		str = typ.String()
 		return str
-	case *StructValue:
-		t := typ.(*StructType)
+	case Struct:
+		t := typ
 		v := val
 		str += t.String()
 		str += "{"
@@ -84,11 +84,11 @@
 		}
 		str += "}"
 		return str
-	case *InterfaceValue:
+	case Interface:
 		return typ.String() + "(" + valueToString(val.Elem()) + ")"
-	case *FuncValue:
+	case Func:
 		v := val
-		return typ.String() + "(" + strconv.Itoa64(int64(v.Get())) + ")"
+		return typ.String() + "(" + strconv.Uitoa64(uint64(v.Pointer())) + ")"
 	default:
 		panic("valueToString: can't print type " + typ.String())
 	}
diff --git a/src/pkg/reflect/type.go b/src/pkg/reflect/type.go
index 2cc1f57..9f3e0bf 100644
--- a/src/pkg/reflect/type.go
+++ b/src/pkg/reflect/type.go
@@ -5,14 +5,11 @@
 // The reflect package implements run-time reflection, allowing a program to
 // manipulate objects with arbitrary types.  The typical use is to take a
 // value with static type interface{} and extract its dynamic type
-// information by calling Typeof, which returns an object with interface
-// type Type.  That contains a pointer to a struct of type *StructType,
-// *IntType, etc. representing the details of the underlying type.  A type
-// switch or type assertion can reveal which.
+// information by calling Typeof, which returns a Type.
 //
-// A call to NewValue creates a Value representing the run-time data; it
-// contains a *StructValue, *IntValue, etc.  MakeZero takes a Type and
-// returns a Value representing a zero value for that type.
+// A call to NewValue returns a Value representing the run-time data.
+// Zero takes a Type and returns a Value representing a zero value
+// for that type.
 package reflect
 
 import (
@@ -22,6 +19,186 @@
 	"unsafe"
 )
 
+// Type is the representation of a Go type.
+//
+// Not all methods apply to all kinds of types.  Restrictions,
+// if any, are noted in the documentation for each method.
+// Use the Kind method to find out the kind of type before
+// calling kind-specific methods.  Calling a method
+// inappropriate to the kind of type causes a run-time panic.
+type Type interface {
+	// Methods applicable to all types.
+
+	// Align returns the alignment in bytes of a value of
+	// this type when allocated in memory.
+	Align() int
+
+	// FieldAlign returns the alignment in bytes of a value of
+	// this type when used as a field in a struct.
+	FieldAlign() int
+
+	// Method returns the i'th method in the type's method set.
+	// It panics if i is not in the range [0, NumMethod()).
+	//
+	// For a non-interface type T or *T, the returned Method's Type and Func
+	// fields describe a function whose first argument is the receiver.
+	//
+	// For an interface type, the returned Method's Type field gives the
+	// method signature, without a receiver, and the Func field is nil.
+	Method(int) Method
+
+	// NumMethods returns the number of methods in the type's method set.
+	NumMethod() int
+
+	// Name returns the type's name within its package.
+	// It returns an empty string for unnamed types.
+	Name() string
+
+	// PkgPath returns the type's package path.
+	// The package path is a full package import path like "container/vector".
+	// PkgPath returns an empty string for unnamed types.
+	PkgPath() string
+
+	// Size returns the number of bytes needed to store
+	// a value of the given type; it is analogous to unsafe.Sizeof.
+	Size() uintptr
+
+	// String returns a string representation of the type.
+	// The string representation may use shortened package names
+	// (e.g., vector instead of "container/vector") and is not
+	// guaranteed to be unique among types.  To test for equality,
+	// compare the Types directly.
+	String() string
+
+	// Kind returns the specific kind of this type.
+	Kind() Kind
+
+	// Methods applicable only to some types, depending on Kind.
+	// The methods allowed for each kind are:
+	//
+	//	Int*, Uint*, Float*, Complex*: Bits
+	//	Array: Elem, Len
+	//	Chan: ChanDir, Elem
+	//	Func: In, NumIn, Out, NumOut, IsVariadic.
+	//	Map: Key, Elem
+	//	Ptr: Elem
+	//	Slice: Elem
+	//	Struct: Field, FieldByIndex, FieldByName, FieldByNameFunc, NumField
+
+	// Bits returns the size of the type in bits.
+	// It panics if the type's Kind is not one of the
+	// sized or unsized Int, Uint, Float, or Complex kinds.
+	Bits() int
+
+	// ChanDir returns a channel type's direction.
+	// It panics if the type's Kind is not Chan.
+	ChanDir() ChanDir
+
+	// IsVariadic returns true if a function type's final input parameter
+	// is a "..." parameter.  If so, t.In(t.NumIn() - 1) returns the parameter's
+	// implicit actual type []T.
+	//
+	// For concreteness, if t represents func(x int, y ... float), then
+	//
+	//	t.NumIn() == 2
+	//	t.In(0) is the reflect.Type for "int"
+	//	t.In(1) is the reflect.Type for "[]float"
+	//	t.IsVariadic() == true
+	//
+	// IsVariadic panics if the type's Kind is not Func.
+	IsVariadic() bool
+
+	// Elem returns a type's element type.
+	// It panics if the type's Kind is not Array, Chan, Map, Ptr, or Slice.
+	Elem() Type
+
+	// Field returns a struct type's i'th field.
+	// It panics if the type's Kind is not Struct.
+	// It panics if i is not in the range [0, NumField()).
+	Field(i int) StructField
+
+	// FieldByIndex returns the nested field corresponding
+	// to the index sequence.  It is equivalent to calling Field
+	// successively for each index i.
+	// It panics if the type's Kind is not Struct.
+	FieldByIndex(index []int) StructField
+
+	// FieldByName returns the struct field with the given name
+	// and a boolean indicating if the field was found.
+	FieldByName(name string) (StructField, bool)
+
+	// FieldByNameFunc returns the first struct field with a name
+	// that satisfies the match function and a boolean indicating if
+	// the field was found.
+	FieldByNameFunc(match func(string) bool) (StructField, bool)
+
+	// In returns the type of a function type's i'th input parameter.
+	// It panics if the type's Kind is not Func.
+	// It panics if i is not in the range [0, NumIn()).
+	In(i int) Type
+
+	// Key returns a map type's key type.
+	// It panics if the type's Kind is not Map.
+	Key() Type
+
+	// Len returns an array type's length.
+	// It panics if the type's Kind is not Array.
+	Len() int
+
+	// NumField returns a struct type's field count.
+	// It panics if the type's Kind is not Struct.
+	NumField() int
+
+	// NumIn returns a function type's input parameter count.
+	// It panics if the type's Kind is not Func.
+	NumIn() int
+
+	// NumOut returns a function type's output parameter count.
+	// It panics if the type's Kind is not Func.
+	NumOut() int
+
+	// Out returns the type of a function type's i'th output parameter.
+	// It panics if the type's Kind is not Func.
+	// It panics if i is not in the range [0, NumOut()).
+	Out(i int) Type
+
+	uncommon() *uncommonType
+}
+
+// A Kind represents the specific kind of type that a Type represents.
+// The zero Kind is not a valid kind.
+type Kind uint8
+
+const (
+	Invalid Kind = iota
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	Array
+	Chan
+	Func
+	Interface
+	Map
+	Ptr
+	Slice
+	String
+	Struct
+	UnsafePointer
+)
+
 /*
  * Copy of data structures from ../runtime/type.go.
  * For comments, see the ones in that file.
@@ -67,48 +244,6 @@
 	methods []method
 }
 
-// BoolType represents a boolean type.
-type BoolType struct {
-	commonType "bool"
-}
-
-// FloatType represents a float type.
-type FloatType struct {
-	commonType "float"
-}
-
-// ComplexType represents a complex type.
-type ComplexType struct {
-	commonType "complex"
-}
-
-// IntType represents a signed integer type.
-type IntType struct {
-	commonType "int"
-}
-
-// UintType represents a uint type.
-type UintType struct {
-	commonType "uint"
-}
-
-// StringType represents a string type.
-type StringType struct {
-	commonType "string"
-}
-
-// UnsafePointerType represents an unsafe.Pointer type.
-type UnsafePointerType struct {
-	commonType "unsafe.Pointer"
-}
-
-// ArrayType represents a fixed array type.
-type ArrayType struct {
-	commonType "array"
-	elem       *runtime.Type
-	len        uintptr
-}
-
 // ChanDir represents a channel type's direction.
 type ChanDir int
 
@@ -118,57 +253,61 @@
 	BothDir = RecvDir | SendDir
 )
 
-// ChanType represents a channel type.
-type ChanType struct {
+
+// arrayType represents a fixed array type.
+type arrayType struct {
+	commonType "array"
+	elem       *runtime.Type
+	len        uintptr
+}
+
+// chanType represents a channel type.
+type chanType struct {
 	commonType "chan"
 	elem       *runtime.Type
 	dir        uintptr
 }
 
-// FuncType represents a function type.
-type FuncType struct {
+// funcType represents a function type.
+type funcType struct {
 	commonType "func"
 	dotdotdot  bool
 	in         []*runtime.Type
 	out        []*runtime.Type
 }
 
-// Method on interface type
+// imethod represents a method on an interface type
 type imethod struct {
 	name    *string
 	pkgPath *string
 	typ     *runtime.Type
 }
 
-// InterfaceType represents an interface type.
-type InterfaceType struct {
+// interfaceType represents an interface type.
+type interfaceType struct {
 	commonType "interface"
 	methods    []imethod
 }
 
-// MapType represents a map type.
-type MapType struct {
+// mapType represents a map type.
+type mapType struct {
 	commonType "map"
 	key        *runtime.Type
 	elem       *runtime.Type
 }
 
-// PtrType represents a pointer type.
-type PtrType struct {
+// ptrType represents a pointer type.
+type ptrType struct {
 	commonType "ptr"
 	elem       *runtime.Type
 }
 
-// SliceType represents a slice type.
-type SliceType struct {
+// sliceType represents a slice type.
+type sliceType struct {
 	commonType "slice"
 	elem       *runtime.Type
 }
 
-// arrayOrSliceType is an unexported method that guarantees only
-// arrays and slices implement ArrayOrSliceType.
-func (*SliceType) arrayOrSliceType() {}
-
 // Struct field
 type structField struct {
 	name    *string
@@ -178,8 +317,8 @@
 	offset  uintptr
 }
 
-// StructType represents a struct type.
-type StructType struct {
+// structType represents a struct type.
+type structType struct {
 	commonType "struct"
 	fields     []structField
 }
@@ -194,106 +333,10 @@
 type Method struct {
 	PkgPath string // empty for uppercase Name
 	Name    string
-	Type    *FuncType
-	Func    *FuncValue
+	Type    Type
+	Func    Value
 }
 
-// Type is the runtime representation of a Go type.
-// Every type implements the methods listed here.
-// Some types implement additional interfaces;
-// use a type switch to find out what kind of type a Type is.
-// Each type in a program has a unique Type, so == on Types
-// corresponds to Go's type equality.
-type Type interface {
-	// PkgPath returns the type's package path.
-	// The package path is a full package import path like "container/vector".
-	// PkgPath returns an empty string for unnamed types.
-	PkgPath() string
-
-	// Name returns the type's name within its package.
-	// Name returns an empty string for unnamed types.
-	Name() string
-
-	// String returns a string representation of the type.
-	// The string representation may use shortened package names
-	// (e.g., vector instead of "container/vector") and is not
-	// guaranteed to be unique among types.  To test for equality,
-	// compare the Types directly.
-	String() string
-
-	// Size returns the number of bytes needed to store
-	// a value of the given type; it is analogous to unsafe.Sizeof.
-	Size() uintptr
-
-	// Bits returns the size of the type in bits.
-	// It is intended for use with numeric types and may overflow
-	// when used for composite types.
-	Bits() int
-
-	// Align returns the alignment of a value of this type
-	// when allocated in memory.
-	Align() int
-
-	// FieldAlign returns the alignment of a value of this type
-	// when used as a field in a struct.
-	FieldAlign() int
-
-	// Kind returns the specific kind of this type.
-	Kind() Kind
-
-	// Method returns the i'th method in the type's method set.
-	//
-	// For a non-interface type T or *T, the returned Method's Type and Func
-	// fields describe a function whose first argument is the receiver.
-	//
-	// For an interface type, the returned Method's Type field gives the
-	// method signature, without a receiver, and the Func field is nil.
-	Method(int) Method
-
-	// NumMethods returns the number of methods in the type's method set.
-	NumMethod() int
-
-	common() *commonType
-	uncommon() *uncommonType
-}
-
-// A Kind represents the specific kind of type that a Type represents.
-// For numeric types, the Kind gives more information than the Type's
-// dynamic type.  For example, the Type of a float32 is FloatType, but
-// the Kind is Float32.
-//
-// The zero Kind is not a valid kind.
-type Kind uint8
-
-const (
-	Bool Kind = 1 + iota
-	Int
-	Int8
-	Int16
-	Int32
-	Int64
-	Uint
-	Uint8
-	Uint16
-	Uint32
-	Uint64
-	Uintptr
-	Float32
-	Float64
-	Complex64
-	Complex128
-	Array
-	Chan
-	Func
-	Interface
-	Map
-	Ptr
-	Slice
-	String
-	Struct
-	UnsafePointer
-)
-
 // High bit says whether type has
 // embedded pointers,to help garbage collector.
 const kindMask = 0x7f
@@ -306,6 +349,7 @@
 }
 
 var kindNames = []string{
+	Invalid:       "invalid",
 	Bool:          "bool",
 	Int:           "int",
 	Int8:          "int8",
@@ -352,11 +396,24 @@
 	return *t.name
 }
 
+func (t *commonType) toType() Type {
+	if t == nil {
+		return nil
+	}
+	return t
+}
+
 func (t *commonType) String() string { return *t.string }
 
 func (t *commonType) Size() uintptr { return t.size }
 
-func (t *commonType) Bits() int { return int(t.size * 8) }
+func (t *commonType) Bits() int {
+	k := t.Kind()
+	if k < Int || k > Complex128 {
+		panic("reflect: Bits of non-arithmetic Type")
+	}
+	return int(t.size) * 8
+}
 
 func (t *commonType) Align() int { return int(t.align) }
 
@@ -377,9 +434,9 @@
 	if p.pkgPath != nil {
 		m.PkgPath = *p.pkgPath
 	}
-	m.Type = toType(*p.typ).(*FuncType)
+	m.Type = toType(p.typ)
 	fn := p.tfn
-	m.Func = &FuncValue{value: value{m.Type, addr(&fn), canSet}}
+	m.Func = Value{&funcValue{value: value{m.Type, addr(&fn), canSet}}}
 	return
 }
 
@@ -393,29 +450,154 @@
 // TODO(rsc): 6g supplies these, but they are not
 // as efficient as they could be: they have commonType
 // as the receiver instead of *commonType.
-func (t *commonType) NumMethod() int { return t.uncommonType.NumMethod() }
+func (t *commonType) NumMethod() int {
+	if t.Kind() == Interface {
+		tt := (*interfaceType)(unsafe.Pointer(t))
+		return tt.NumMethod()
+	}
+	return t.uncommonType.NumMethod()
+}
 
-func (t *commonType) Method(i int) (m Method) { return t.uncommonType.Method(i) }
+func (t *commonType) Method(i int) (m Method) {
+	if t.Kind() == Interface {
+		tt := (*interfaceType)(unsafe.Pointer(t))
+		return tt.Method(i)
+	}
+	return t.uncommonType.Method(i)
+}
 
-func (t *commonType) PkgPath() string { return t.uncommonType.PkgPath() }
+func (t *commonType) PkgPath() string {
+	return t.uncommonType.PkgPath()
+}
 
-func (t *commonType) Name() string { return t.uncommonType.Name() }
+func (t *commonType) Name() string {
+	return t.uncommonType.Name()
+}
 
-// Len returns the number of elements in the array.
-func (t *ArrayType) Len() int { return int(t.len) }
+func (t *commonType) ChanDir() ChanDir {
+	if t.Kind() != Chan {
+		panic("reflect: ChanDir of non-chan type")
+	}
+	tt := (*chanType)(unsafe.Pointer(t))
+	return ChanDir(tt.dir)
+}
 
-// Elem returns the type of the array's elements.
-func (t *ArrayType) Elem() Type { return toType(*t.elem) }
+func (t *commonType) IsVariadic() bool {
+	if t.Kind() != Func {
+		panic("reflect: IsVariadic of non-func type")
+	}
+	tt := (*funcType)(unsafe.Pointer(t))
+	return tt.dotdotdot
+}
 
-// arrayOrSliceType is an unexported method that guarantees only
-// arrays and slices implement ArrayOrSliceType.
-func (*ArrayType) arrayOrSliceType() {}
+func (t *commonType) Elem() Type {
+	switch t.Kind() {
+	case Array:
+		tt := (*arrayType)(unsafe.Pointer(t))
+		return toType(tt.elem)
+	case Chan:
+		tt := (*chanType)(unsafe.Pointer(t))
+		return toType(tt.elem)
+	case Map:
+		tt := (*mapType)(unsafe.Pointer(t))
+		return toType(tt.elem)
+	case Ptr:
+		tt := (*ptrType)(unsafe.Pointer(t))
+		return toType(tt.elem)
+	case Slice:
+		tt := (*sliceType)(unsafe.Pointer(t))
+		return toType(tt.elem)
+	}
+	panic("reflect; Elem of invalid type")
+}
 
-// Dir returns the channel direction.
-func (t *ChanType) Dir() ChanDir { return ChanDir(t.dir) }
+func (t *commonType) Field(i int) StructField {
+	if t.Kind() != Struct {
+		panic("reflect: Field of non-struct type")
+	}
+	tt := (*structType)(unsafe.Pointer(t))
+	return tt.Field(i)
+}
 
-// Elem returns the channel's element type.
-func (t *ChanType) Elem() Type { return toType(*t.elem) }
+func (t *commonType) FieldByIndex(index []int) StructField {
+	if t.Kind() != Struct {
+		panic("reflect: FieldByIndex of non-struct type")
+	}
+	tt := (*structType)(unsafe.Pointer(t))
+	return tt.FieldByIndex(index)
+}
+
+func (t *commonType) FieldByName(name string) (StructField, bool) {
+	if t.Kind() != Struct {
+		panic("reflect: FieldByName of non-struct type")
+	}
+	tt := (*structType)(unsafe.Pointer(t))
+	return tt.FieldByName(name)
+}
+
+func (t *commonType) FieldByNameFunc(match func(string) bool) (StructField, bool) {
+	if t.Kind() != Struct {
+		panic("reflect: FieldByNameFunc of non-struct type")
+	}
+	tt := (*structType)(unsafe.Pointer(t))
+	return tt.FieldByNameFunc(match)
+}
+
+func (t *commonType) In(i int) Type {
+	if t.Kind() != Func {
+		panic("reflect: In of non-func type")
+	}
+	tt := (*funcType)(unsafe.Pointer(t))
+	return toType(tt.in[i])
+}
+
+func (t *commonType) Key() Type {
+	if t.Kind() != Map {
+		panic("reflect: Key of non-map type")
+	}
+	tt := (*mapType)(unsafe.Pointer(t))
+	return toType(tt.key)
+}
+
+func (t *commonType) Len() int {
+	if t.Kind() != Array {
+		panic("reflect: Len of non-array type")
+	}
+	tt := (*arrayType)(unsafe.Pointer(t))
+	return int(tt.len)
+}
+
+func (t *commonType) NumField() int {
+	if t.Kind() != Struct {
+		panic("reflect: NumField of non-struct type")
+	}
+	tt := (*structType)(unsafe.Pointer(t))
+	return len(tt.fields)
+}
+
+func (t *commonType) NumIn() int {
+	if t.Kind() != Func {
+		panic("reflect; NumIn of non-func type")
+	}
+	tt := (*funcType)(unsafe.Pointer(t))
+	return len(tt.in)
+}
+
+func (t *commonType) NumOut() int {
+	if t.Kind() != Func {
+		panic("reflect; NumOut of non-func type")
+	}
+	tt := (*funcType)(unsafe.Pointer(t))
+	return len(tt.out)
+}
+
+func (t *commonType) Out(i int) Type {
+	if t.Kind() != Func {
+		panic("reflect: Out of non-func type")
+	}
+	tt := (*funcType)(unsafe.Pointer(t))
+	return toType(tt.out[i])
+}
 
 func (d ChanDir) String() string {
 	switch d {
@@ -429,43 +611,8 @@
 	return "ChanDir" + strconv.Itoa(int(d))
 }
 
-// In returns the type of the i'th function input parameter.
-func (t *FuncType) In(i int) Type {
-	if i < 0 || i >= len(t.in) {
-		return nil
-	}
-	return toType(*t.in[i])
-}
-
-// DotDotDot returns true if the final function input parameter
-// is a "..." parameter.  If so, t.In(t.NumIn() - 1) returns the
-// parameter's underlying static type []T.
-//
-// For concreteness, if t is func(x int, y ... float), then
-//
-//	t.NumIn() == 2
-//	t.In(0) is the reflect.Type for "int"
-//	t.In(1) is the reflect.Type for "[]float"
-//	t.DotDotDot() == true
-//
-func (t *FuncType) DotDotDot() bool { return t.dotdotdot }
-
-// NumIn returns the number of input parameters.
-func (t *FuncType) NumIn() int { return len(t.in) }
-
-// Out returns the type of the i'th function output parameter.
-func (t *FuncType) Out(i int) Type {
-	if i < 0 || i >= len(t.out) {
-		return nil
-	}
-	return toType(*t.out[i])
-}
-
-// NumOut returns the number of function output parameters.
-func (t *FuncType) NumOut() int { return len(t.out) }
-
 // Method returns the i'th method in the type's method set.
-func (t *InterfaceType) Method(i int) (m Method) {
+func (t *interfaceType) Method(i int) (m Method) {
 	if i < 0 || i >= len(t.methods) {
 		return
 	}
@@ -474,24 +621,12 @@
 	if p.pkgPath != nil {
 		m.PkgPath = *p.pkgPath
 	}
-	m.Type = toType(*p.typ).(*FuncType)
+	m.Type = toType(p.typ)
 	return
 }
 
 // NumMethod returns the number of interface methods in the type's method set.
-func (t *InterfaceType) NumMethod() int { return len(t.methods) }
-
-// Key returns the map key type.
-func (t *MapType) Key() Type { return toType(*t.key) }
-
-// Elem returns the map element type.
-func (t *MapType) Elem() Type { return toType(*t.elem) }
-
-// Elem returns the pointer element type.
-func (t *PtrType) Elem() Type { return toType(*t.elem) }
-
-// Elem returns the type of the slice's elements.
-func (t *SliceType) Elem() Type { return toType(*t.elem) }
+func (t *interfaceType) NumMethod() int { return len(t.methods) }
 
 type StructField struct {
 	PkgPath   string // empty for uppercase Name
@@ -504,18 +639,18 @@
 }
 
 // Field returns the i'th struct field.
-func (t *StructType) Field(i int) (f StructField) {
+func (t *structType) Field(i int) (f StructField) {
 	if i < 0 || i >= len(t.fields) {
 		return
 	}
 	p := t.fields[i]
-	f.Type = toType(*p.typ)
+	f.Type = toType(p.typ)
 	if p.name != nil {
 		f.Name = *p.name
 	} else {
 		t := f.Type
-		if pt, ok := t.(*PtrType); ok {
-			t = pt.Elem()
+		if t.Kind() == Ptr {
+			t = t.Elem()
 		}
 		f.Name = t.Name()
 		f.Anonymous = true
@@ -535,29 +670,24 @@
 //            is wrong for FieldByIndex?
 
 // FieldByIndex returns the nested field corresponding to index.
-func (t *StructType) FieldByIndex(index []int) (f StructField) {
+func (t *structType) FieldByIndex(index []int) (f StructField) {
+	f.Type = Type(t.toType())
 	for i, x := range index {
 		if i > 0 {
 			ft := f.Type
-			if pt, ok := ft.(*PtrType); ok {
-				ft = pt.Elem()
+			if ft.Kind() == Ptr && ft.Elem().Kind() == Struct {
+				ft = ft.Elem()
 			}
-			if st, ok := ft.(*StructType); ok {
-				t = st
-			} else {
-				var f0 StructField
-				f = f0
-				return
-			}
+			f.Type = ft
 		}
-		f = t.Field(x)
+		f = f.Type.Field(x)
 	}
 	return
 }
 
 const inf = 1 << 30 // infinity - no struct has that many nesting levels
 
-func (t *StructType) fieldByNameFunc(match func(string) bool, mark map[*StructType]bool, depth int) (ff StructField, fd int) {
+func (t *structType) fieldByNameFunc(match func(string) bool, mark map[*structType]bool, depth int) (ff StructField, fd int) {
 	fd = inf // field depth
 
 	if mark[t] {
@@ -578,8 +708,8 @@
 			d = depth
 		case f.Anonymous:
 			ft := f.Type
-			if pt, ok := ft.(*PtrType); ok {
-				ft = pt.Elem()
+			if ft.Kind() == Ptr {
+				ft = ft.Elem()
 			}
 			switch {
 			case match(ft.Name()):
@@ -587,7 +717,8 @@
 				d = depth
 			case fd > depth:
 				// No top-level field yet; look inside nested structs.
-				if st, ok := ft.(*StructType); ok {
+				if ft.Kind() == Struct {
+					st := (*structType)(unsafe.Pointer(ft.(*commonType)))
 					f, d = st.fieldByNameFunc(match, mark, depth+1)
 				}
 			}
@@ -626,97 +757,54 @@
 
 // FieldByName returns the struct field with the given name
 // and a boolean to indicate if the field was found.
-func (t *StructType) FieldByName(name string) (f StructField, present bool) {
+func (t *structType) FieldByName(name string) (f StructField, present bool) {
 	return t.FieldByNameFunc(func(s string) bool { return s == name })
 }
 
 // FieldByNameFunc returns the struct field with a name that satisfies the
 // match function and a boolean to indicate if the field was found.
-func (t *StructType) FieldByNameFunc(match func(string) bool) (f StructField, present bool) {
-	if ff, fd := t.fieldByNameFunc(match, make(map[*StructType]bool), 0); fd < inf {
+func (t *structType) FieldByNameFunc(match func(string) bool) (f StructField, present bool) {
+	if ff, fd := t.fieldByNameFunc(match, make(map[*structType]bool), 0); fd < inf {
 		ff.Index = ff.Index[0 : fd+1]
 		f, present = ff, true
 	}
 	return
 }
 
-// NumField returns the number of struct fields.
-func (t *StructType) NumField() int { return len(t.fields) }
-
 // Convert runtime type to reflect type.
-// Same memory layouts, different method sets.
-func toType(i interface{}) Type {
-	switch v := i.(type) {
-	case nil:
-		return nil
-	case *runtime.BoolType:
-		return (*BoolType)(unsafe.Pointer(v))
-	case *runtime.FloatType:
-		return (*FloatType)(unsafe.Pointer(v))
-	case *runtime.ComplexType:
-		return (*ComplexType)(unsafe.Pointer(v))
-	case *runtime.IntType:
-		return (*IntType)(unsafe.Pointer(v))
-	case *runtime.StringType:
-		return (*StringType)(unsafe.Pointer(v))
-	case *runtime.UintType:
-		return (*UintType)(unsafe.Pointer(v))
-	case *runtime.UnsafePointerType:
-		return (*UnsafePointerType)(unsafe.Pointer(v))
-	case *runtime.ArrayType:
-		return (*ArrayType)(unsafe.Pointer(v))
-	case *runtime.ChanType:
-		return (*ChanType)(unsafe.Pointer(v))
-	case *runtime.FuncType:
-		return (*FuncType)(unsafe.Pointer(v))
-	case *runtime.InterfaceType:
-		return (*InterfaceType)(unsafe.Pointer(v))
-	case *runtime.MapType:
-		return (*MapType)(unsafe.Pointer(v))
-	case *runtime.PtrType:
-		return (*PtrType)(unsafe.Pointer(v))
-	case *runtime.SliceType:
-		return (*SliceType)(unsafe.Pointer(v))
-	case *runtime.StructType:
-		return (*StructType)(unsafe.Pointer(v))
+func toType(p *runtime.Type) Type {
+	type hdr struct {
+		x interface{}
+		t commonType
 	}
-	println(i)
-	panic("toType")
-}
-
-// ArrayOrSliceType is the common interface implemented
-// by both ArrayType and SliceType.
-type ArrayOrSliceType interface {
-	Type
-	Elem() Type
-	arrayOrSliceType() // Guarantees only Array and Slice implement this interface.
+	t := &(*hdr)(unsafe.Pointer(p)).t
+	return t.toType()
 }
 
 // Typeof returns the reflection Type of the value in the interface{}.
-func Typeof(i interface{}) Type { return toType(unsafe.Typeof(i)) }
+func Typeof(i interface{}) Type {
+	type hdr struct {
+		typ *byte
+		val *commonType
+	}
+	rt := unsafe.Typeof(i)
+	t := (*(*hdr)(unsafe.Pointer(&rt))).val
+	return t.toType()
+}
 
 // ptrMap is the cache for PtrTo.
 var ptrMap struct {
 	sync.RWMutex
-	m map[Type]*PtrType
-}
-
-// runtimePtrType is the runtime layout for a *PtrType.
-// The memory immediately before the *PtrType is always
-// the canonical runtime.Type to be used for a *runtime.Type
-// describing this PtrType.
-type runtimePtrType struct {
-	runtime.Type
-	runtime.PtrType
+	m map[*commonType]*ptrType
 }
 
 // PtrTo returns the pointer type with element t.
 // For example, if t represents type Foo, PtrTo(t) represents *Foo.
-func PtrTo(t Type) *PtrType {
+func PtrTo(t Type) Type {
 	// If t records its pointer-to type, use it.
-	ct := t.common()
+	ct := t.(*commonType)
 	if p := ct.ptrToThis; p != nil {
-		return toType(*p).(*PtrType)
+		return toType(p)
 	}
 
 	// Otherwise, synthesize one.
@@ -726,35 +814,34 @@
 	// the type structures in read-only memory.
 	ptrMap.RLock()
 	if m := ptrMap.m; m != nil {
-		if p := m[t]; p != nil {
+		if p := m[ct]; p != nil {
 			ptrMap.RUnlock()
-			return p
+			return p.commonType.toType()
 		}
 	}
 	ptrMap.RUnlock()
 	ptrMap.Lock()
 	if ptrMap.m == nil {
-		ptrMap.m = make(map[Type]*PtrType)
+		ptrMap.m = make(map[*commonType]*ptrType)
 	}
-	p := ptrMap.m[t]
+	p := ptrMap.m[ct]
 	if p != nil {
 		// some other goroutine won the race and created it
 		ptrMap.Unlock()
 		return p
 	}
 
-	// runtime.Type value is always right before type structure.
-	// 2*ptrSize is size of interface header
-	rt := (*runtime.Type)(unsafe.Pointer(uintptr(unsafe.Pointer(ct)) - uintptr(unsafe.Sizeof(runtime.Type(nil)))))
+	var rt struct {
+		i runtime.Type
+		ptrType
+	}
+	rt.i = (*runtime.PtrType)(unsafe.Pointer(&rt.ptrType))
 
-	rp := new(runtimePtrType)
-	rp.Type = &rp.PtrType
-
-	// initialize rp.PtrType using *byte's PtrType as a prototype.
+	// initialize p using *byte's PtrType as a prototype.
 	// have to do assignment as PtrType, not runtime.PtrType,
 	// in order to write to unexported fields.
-	p = (*PtrType)(unsafe.Pointer(&rp.PtrType))
-	bp := (*PtrType)(unsafe.Pointer(unsafe.Typeof((*byte)(nil)).(*runtime.PtrType)))
+	p = &rt.ptrType
+	bp := (*ptrType)(unsafe.Pointer(unsafe.Typeof((*byte)(nil)).(*runtime.PtrType)))
 	*p = *bp
 
 	s := "*" + *ct.string
@@ -769,9 +856,9 @@
 
 	p.uncommonType = nil
 	p.ptrToThis = nil
-	p.elem = rt
+	p.elem = (*runtime.Type)(unsafe.Pointer(uintptr(unsafe.Pointer(ct)) - uintptr(unsafe.Offsetof(rt.ptrType))))
 
-	ptrMap.m[t] = (*PtrType)(unsafe.Pointer(&rp.PtrType))
+	ptrMap.m[ct] = p
 	ptrMap.Unlock()
-	return p
+	return p.commonType.toType()
 }
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go
index 01a40ec..eeae6cc 100644
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -41,10 +41,482 @@
 	}
 }
 
-// Value is the common interface to reflection values.
-// The implementations of Value (e.g., ArrayValue, StructValue)
+// Value is the reflection interface to a Go value.
+//
+// Not all methods apply to all kinds of values.  Restrictions,
+// if any, are noted in the documentation for each method.
+// Use the Kind method to find out the kind of value before
+// calling kind-specific methods.  Calling a method
+// inappropriate to the kind of type causes a run time panic.
+//
+// The zero Value represents no value.
+// Its IsValid method returns false, its Kind method returns Invalid,
+// its String method returns "<invalid Value>", and all other methods panic.
+// Most functions and methods never return an invalid value.
+// If one does, its documentation states the conditions explicitly.
+type Value struct {
+	Internal valueInterface
+}
+
+// TODO(rsc): This implementation of Value is a just a façade
+// in front of the old implementation, now called valueInterface.
+// A future CL will change it to a real implementation.
+// Changing the API is already a big enough step for one CL.
+
+// A ValueError occurs when a Value method is invoked on
+// a Value that does not support it.  Such cases are documented
+// in the description of each method.
+type ValueError struct {
+	Method string
+	Kind   Kind
+}
+
+func (e *ValueError) String() string {
+	if e.Kind == 0 {
+		return "reflect: call of " + e.Method + " on zero Value"
+	}
+	return "reflect: call of " + e.Method + " on " + e.Kind.String() + " Value"
+}
+
+// methodName returns the name of the calling method,
+// assumed to be two stack frames above.
+func methodName() string {
+	pc, _, _, _ := runtime.Caller(2)
+	f := runtime.FuncForPC(pc)
+	if f == nil {
+		return "unknown method"
+	}
+	return f.Name()
+}
+
+func (v Value) internal() valueInterface {
+	vi := v.Internal
+	if vi == nil {
+		panic(&ValueError{methodName(), 0})
+	}
+	return vi
+}
+
+func (v Value) panicIfNot(want Kind) valueInterface {
+	vi := v.Internal
+	if vi == nil {
+		panic(&ValueError{methodName(), 0})
+	}
+	if k := vi.Kind(); k != want {
+		panic(&ValueError{methodName(), k})
+	}
+	return vi
+}
+
+func (v Value) panicIfNots(wants []Kind) valueInterface {
+	vi := v.Internal
+	if vi == nil {
+		panic(&ValueError{methodName(), 0})
+	}
+	k := vi.Kind()
+	for _, want := range wants {
+		if k == want {
+			return vi
+		}
+	}
+	panic(&ValueError{methodName(), k})
+}
+
+// Addr returns a pointer value representing the address of v.
+// It panics if CanAddr() returns false.
+// Addr is typically used to obtain a pointer to a struct field
+// or slice element in order to call a method that requires a
+// pointer receiver.
+func (v Value) Addr() Value {
+	return v.internal().Addr()
+}
+
+// Bool returns v's underlying value.
+// It panics if v's kind is not Bool.
+func (v Value) Bool() bool {
+	u := v.panicIfNot(Bool).(*boolValue)
+	return u.Get()
+}
+
+// CanAddr returns true if the value's address can be obtained with Addr.
+// Such values are called addressable.  A value is addressable if it is
+// an element of a slice, an element of an addressable array,
+// a field of an addressable struct, the result of dereferencing a pointer,
+// or the result of a call to NewValue, MakeChan, MakeMap, or Zero.
+// If CanAddr returns false, calling Addr will panic.
+func (v Value) CanAddr() bool {
+	return v.internal().CanAddr()
+}
+
+// CanSet returns true if the value of v can be changed.
+// Values obtained by the use of unexported struct fields
+// can be read but not set.
+// If CanSet returns false, calling Set or any type-specific
+// setter (e.g., SetBool, SetInt64) will panic.
+func (v Value) CanSet() bool {
+	return v.internal().CanSet()
+}
+
+// Call calls the function v with the input parameters in.
+// It panics if v's Kind is not Func.
+// It returns the output parameters as Values.
+func (v Value) Call(in []Value) []Value {
+	return v.panicIfNot(Func).(*funcValue).Call(in)
+}
+
+var capKinds = []Kind{Array, Chan, Slice}
+
+type capper interface {
+	Cap() int
+}
+
+// Cap returns v's capacity.
+// It panics if v's Kind is not Array, Chan, or Slice.
+func (v Value) Cap() int {
+	return v.panicIfNots(capKinds).(capper).Cap()
+}
+
+// Close closes the channel v.
+// It panics if v's Kind is not Chan.
+func (v Value) Close() {
+	v.panicIfNot(Chan).(*chanValue).Close()
+}
+
+var complexKinds = []Kind{Complex64, Complex128}
+
+// Complex returns v's underlying value, as a complex128.
+// It panics if v's Kind is not Complex64 or Complex128
+func (v Value) Complex() complex128 {
+	return v.panicIfNots(complexKinds).(*complexValue).Get()
+}
+
+var interfaceOrPtr = []Kind{Interface, Ptr}
+
+type elemer interface {
+	Elem() Value
+}
+
+// Elem returns the value that the interface v contains
+// or that the pointer v points to.
+// It panics if v's Kind is not Interface or Ptr.
+// It returns the zero Value if v is nil.
+func (v Value) Elem() Value {
+	return v.panicIfNots(interfaceOrPtr).(elemer).Elem()
+}
+
+// Field returns the i'th field of the struct v.
+// It panics if v's Kind is not Struct.
+func (v Value) Field(i int) Value {
+	return v.panicIfNot(Struct).(*structValue).Field(i)
+}
+
+// FieldByIndex returns the nested field corresponding to index.
+// It panics if v's Kind is not struct.
+func (v Value) FieldByIndex(index []int) Value {
+	return v.panicIfNot(Struct).(*structValue).FieldByIndex(index)
+}
+
+// FieldByName returns the struct field with the given name.
+// It returns the zero Value if no field was found.
+// It panics if v's Kind is not struct.
+func (v Value) FieldByName(name string) Value {
+	return v.panicIfNot(Struct).(*structValue).FieldByName(name)
+}
+
+// FieldByNameFunc returns the struct field with a name
+// that satisfies the match function.
+// It panics if v's Kind is not struct.
+// It returns the zero Value if no field was found.
+func (v Value) FieldByNameFunc(match func(string) bool) Value {
+	return v.panicIfNot(Struct).(*structValue).FieldByNameFunc(match)
+}
+
+var floatKinds = []Kind{Float32, Float64}
+
+// Float returns v's underlying value, as an float64.
+// It panics if v's Kind is not Float32 or Float64
+func (v Value) Float() float64 {
+	return v.panicIfNots(floatKinds).(*floatValue).Get()
+}
+
+var arrayOrSlice = []Kind{Array, Slice}
+
+// Index returns v's i'th element.
+// It panics if v's Kind is not Array or Slice.
+func (v Value) Index(i int) Value {
+	return v.panicIfNots(arrayOrSlice).(arrayOrSliceValue).Elem(i)
+}
+
+var intKinds = []Kind{Int, Int8, Int16, Int32, Int64}
+
+// Int returns v's underlying value, as an int64.
+// It panics if v's Kind is not a sized or unsized Int kind.
+func (v Value) Int() int64 {
+	return v.panicIfNots(intKinds).(*intValue).Get()
+}
+
+// Interface returns v's value as an interface{}.
+// If v is a method obtained by invoking Value.Method
+// (as opposed to Type.Method), Interface cannot return an
+// interface value, so it panics.
+func (v Value) Interface() interface{} {
+	return v.internal().Interface()
+}
+
+// InterfaceData returns the interface v's value as a uintptr pair.
+// It panics if v's Kind is not Interface.
+func (v Value) InterfaceData() [2]uintptr {
+	return v.panicIfNot(Interface).(*interfaceValue).Get()
+}
+
+var nilKinds = []Kind{Chan, Func, Interface, Map, Ptr, Slice}
+
+type isNiller interface {
+	IsNil() bool
+}
+
+// IsNil returns true if v is a nil value.
+// It panics if v's Kind is not Chan, Func, Interface, Map, Ptr, or Slice.
+func (v Value) IsNil() bool {
+	return v.panicIfNots(nilKinds).(isNiller).IsNil()
+}
+
+// IsValid returns true if v represents a value.
+// It returns false if v is the zero Value.
+// If IsValid returns false, all other methods except String panic.
+// Most functions and methods never return an invalid value.
+// If one does, its documentation states the conditions explicitly.
+func (v Value) IsValid() bool {
+	return v.Internal != nil
+}
+
+// Kind returns v's Kind.
+// If v is the zero Value (IsValid returns false), Kind returns Invalid.
+func (v Value) Kind() Kind {
+	if v.Internal == nil {
+		return Invalid
+	}
+	return v.internal().Kind()
+}
+
+var lenKinds = []Kind{Array, Chan, Map, Slice}
+
+type lenner interface {
+	Len() int
+}
+
+// Len returns v's length.
+// It panics if v's Kind is not Array, Chan, Map, or Slice.
+func (v Value) Len() int {
+	return v.panicIfNots(lenKinds).(lenner).Len()
+}
+
+// MapIndex returns the value associated with key in the map v.
+// It panics if v's Kind is not Map.
+// It returns the zero Value if key is not found in the map.
+func (v Value) MapIndex(key Value) Value {
+	return v.panicIfNot(Map).(*mapValue).Elem(key)
+}
+
+// MapKeys returns a slice containing all the keys present in the map,
+// in unspecified order.
+// It panics if v's Kind is not Map.
+func (v Value) MapKeys() []Value {
+	return v.panicIfNot(Map).(*mapValue).Keys()
+}
+
+// Method returns a function value corresponding to v's i'th method.
+// The arguments to a Call on the returned function should not include
+// a receiver; the returned function will always use v as the receiver.
+func (v Value) Method(i int) Value {
+	return v.internal().Method(i)
+}
+
+// NumField returns the number of fields in the struct v.
+// It panics if v's Kind is not Struct.
+func (v Value) NumField() int {
+	return v.panicIfNot(Struct).(*structValue).NumField()
+}
+
+// OverflowComplex returns true if the complex128 x cannot be represented by v's type.
+// It panics if v's Kind is not Complex64 or Complex128.
+func (v Value) OverflowComplex(x complex128) bool {
+	return v.panicIfNots(complexKinds).(*complexValue).Overflow(x)
+}
+
+// OverflowFloat returns true if the float64 x cannot be represented by v's type.
+// It panics if v's Kind is not Float32 or Float64.
+func (v Value) OverflowFloat(x float64) bool {
+	return v.panicIfNots(floatKinds).(*floatValue).Overflow(x)
+}
+
+// OverflowInt returns true if the int64 x cannot be represented by v's type.
+// It panics if v's Kind is not a sized or unsized Int kind.
+func (v Value) OverflowInt(x int64) bool {
+	return v.panicIfNots(intKinds).(*intValue).Overflow(x)
+}
+
+// OverflowUint returns true if the uint64 x cannot be represented by v's type.
+// It panics if v's Kind is not a sized or unsized Uint kind.
+func (v Value) OverflowUint(x uint64) bool {
+	return v.panicIfNots(uintKinds).(*uintValue).Overflow(x)
+}
+
+var pointerKinds = []Kind{Chan, Func, Map, Ptr, Slice, UnsafePointer}
+
+type uintptrGetter interface {
+	Get() uintptr
+}
+
+// Pointer returns v's value as a uintptr.
+// It returns uintptr instead of unsafe.Pointer so that
+// code using reflect cannot obtain unsafe.Pointers
+// without importing the unsafe package explicitly.
+// It panics if v's Kind is not Chan, Func, Map, Ptr, Slice, or UnsafePointer.
+func (v Value) Pointer() uintptr {
+	return v.panicIfNots(pointerKinds).(uintptrGetter).Get()
+}
+
+
+// Recv receives and returns a value from the channel v.
+// It panics if v's Kind is not Chan.
+// The receive blocks until a value is ready.
+// The boolean value ok is true if the value x corresponds to a send
+// on the channel, false if it is a zero value received because the channel is closed.
+func (v Value) Recv() (x Value, ok bool) {
+	return v.panicIfNot(Chan).(*chanValue).Recv()
+}
+
+// Send sends x on the channel v.
+// It panics if v's kind is not Chan or if x's type is not the same type as v's element type.
+func (v Value) Send(x Value) {
+	v.panicIfNot(Chan).(*chanValue).Send(x)
+}
+
+// Set assigns x to the value v; x must have the same type as v.
+// It panics if CanSet() returns false or if x is the zero Value.
+func (v Value) Set(x Value) {
+	x.internal()
+	v.internal().SetValue(x)
+}
+
+// SetBool sets v's underlying value.
+// It panics if v's Kind is not Bool or if CanSet() is false.
+func (v Value) SetBool(x bool) {
+	v.panicIfNot(Bool).(*boolValue).Set(x)
+}
+
+// SetComplex sets v's underlying value to x.
+// It panics if v's Kind is not Complex64 or Complex128, or if CanSet() is false.
+func (v Value) SetComplex(x complex128) {
+	v.panicIfNots(complexKinds).(*complexValue).Set(x)
+}
+
+// SetFloat sets v's underlying value to x.
+// It panics if v's Kind is not Float32 or Float64, or if CanSet() is false.
+func (v Value) SetFloat(x float64) {
+	v.panicIfNots(floatKinds).(*floatValue).Set(x)
+}
+
+// SetInt sets v's underlying value to x.
+// It panics if v's Kind is not a sized or unsized Int kind, or if CanSet() is false.
+func (v Value) SetInt(x int64) {
+	v.panicIfNots(intKinds).(*intValue).Set(x)
+}
+
+// SetLen sets v's length to n.
+// It panics if v's Kind is not Slice.
+func (v Value) SetLen(n int) {
+	v.panicIfNot(Slice).(*sliceValue).SetLen(n)
+}
+
+// SetMapIndex sets the value associated with key in the map v to val.
+// It panics if v's Kind is not Map.
+// If val is the zero Value, SetMapIndex deletes the key from the map.
+func (v Value) SetMapIndex(key, val Value) {
+	v.panicIfNot(Map).(*mapValue).SetElem(key, val)
+}
+
+// SetUint sets v's underlying value to x.
+// It panics if v's Kind is not a sized or unsized Uint kind, or if CanSet() is false.
+func (v Value) SetUint(x uint64) {
+	v.panicIfNots(uintKinds).(*uintValue).Set(x)
+}
+
+// SetPointer sets the unsafe.Pointer value v to x.
+// It panics if v's Kind is not UnsafePointer.
+func (v Value) SetPointer(x unsafe.Pointer) {
+	v.panicIfNot(UnsafePointer).(*unsafePointerValue).Set(x)
+}
+
+// SetString sets v's underlying value to x.
+// It panics if v's Kind is not String or if CanSet() is false.
+func (v Value) SetString(x string) {
+	v.panicIfNot(String).(*stringValue).Set(x)
+}
+
+// BUG(rsc): Value.Slice should allow slicing arrays.
+
+// Slice returns a slice of v.
+// It panics if v's Kind is not Slice.
+func (v Value) Slice(beg, end int) Value {
+	return v.panicIfNot(Slice).(*sliceValue).Slice(beg, end)
+}
+
+// String returns the string v's underlying value, as a string.
+// String is a special case because of Go's String method convention.
+// Unlike the other getters, it does not panic if v's Kind is not String.
+// Instead, it returns a string of the form "<T value>" where T is v's type.
+func (v Value) String() string {
+	vi := v.Internal
+	if vi == nil {
+		return "<invalid Value>"
+	}
+	if vi.Kind() == String {
+		return vi.(*stringValue).Get()
+	}
+	return "<" + vi.Type().String() + " Value>"
+}
+
+// TryRecv attempts to receive a value from the channel v but will not block.
+// It panics if v's Kind is not Chan.
+// If the receive cannot finish without blocking, x is the zero Value.
+// The boolean ok is true if the value x corresponds to a send
+// on the channel, false if it is a zero value received because the channel is closed.
+func (v Value) TryRecv() (x Value, ok bool) {
+	return v.panicIfNot(Chan).(*chanValue).TryRecv()
+}
+
+// TrySend attempts to send x on the channel v but will not block.
+// It panics if v's Kind is not Chan.
+// It returns true if the value was sent, false otherwise.
+func (v Value) TrySend(x Value) bool {
+	return v.panicIfNot(Chan).(*chanValue).TrySend(x)
+}
+
+// Type returns v's type.
+func (v Value) Type() Type {
+	return v.internal().Type()
+}
+
+var uintKinds = []Kind{Uint, Uint8, Uint16, Uint32, Uint64, Uintptr}
+
+// Uint returns v's underlying value, as a uint64.
+// It panics if v's Kind is not a sized or unsized Uint kind.
+func (v Value) Uint() uint64 {
+	return v.panicIfNots(uintKinds).(*uintValue).Get()
+}
+
+// UnsafeAddr returns a pointer to v's data.
+// It is for advanced clients that also import the "unsafe" package.
+func (v Value) UnsafeAddr() uintptr {
+	return v.internal().UnsafeAddr()
+}
+
+// valueInterface is the common interface to reflection values.
+// The implementations of Value (e.g., arrayValue, structValue)
 // have additional type-specific methods.
-type Value interface {
+type valueInterface interface {
 	// Type returns the value's type.
 	Type() Type
 
@@ -64,7 +536,7 @@
 	// Such values are called addressable.  A value is addressable if it is
 	// an element of a slice, an element of an addressable array,
 	// a field of an addressable struct, the result of dereferencing a pointer,
-	// or the result of a call to NewValue, MakeChan, MakeMap, or MakeZero.
+	// or the result of a call to NewValue, MakeChan, MakeMap, or Zero.
 	// If CanAddr returns false, calling Addr will panic.
 	CanAddr() bool
 
@@ -72,17 +544,19 @@
 	// If the value is not addressable, Addr panics.
 	// Addr is typically used to obtain a pointer to a struct field or slice element
 	// in order to call a method that requires a pointer receiver.
-	Addr() *PtrValue
+	Addr() Value
 
 	// UnsafeAddr returns a pointer to the underlying data.
 	// It is for advanced clients that also import the "unsafe" package.
 	UnsafeAddr() uintptr
 
-	// Method returns a FuncValue corresponding to the value's i'th method.
-	// The arguments to a Call on the returned FuncValue
-	// should not include a receiver; the FuncValue will use
+	// Method returns a funcValue corresponding to the value's i'th method.
+	// The arguments to a Call on the returned funcValue
+	// should not include a receiver; the funcValue will use
 	// the value as the receiver.
-	Method(i int) *FuncValue
+	Method(i int) Value
+
+	Kind() Kind
 
 	getAddr() addr
 }
@@ -97,7 +571,7 @@
 // value is the common implementation of most values.
 // It is embedded in other, public struct types, but always
 // with a unique tag like "uint" or "float" so that the client cannot
-// convert from, say, *UintValue to *FloatValue.
+// convert from, say, *uintValue to *floatValue.
 type value struct {
 	typ  Type
 	addr addr
@@ -106,7 +580,9 @@
 
 func (v *value) Type() Type { return v.typ }
 
-func (v *value) Addr() *PtrValue {
+func (v *value) Kind() Kind { return v.typ.Kind() }
+
+func (v *value) Addr() Value {
 	if !v.CanAddr() {
 		panic("reflect: cannot take address of value")
 	}
@@ -119,7 +595,7 @@
 	// the caller would get the address of a -
 	// but it doesn't match the Go model.
 	// The language doesn't let you say &&v.
-	return newValue(PtrTo(v.typ), addr(&a), flag).(*PtrValue)
+	return newValue(PtrTo(v.typ), addr(&a), flag)
 }
 
 func (v *value) UnsafeAddr() uintptr { return uintptr(v.addr) }
@@ -127,7 +603,8 @@
 func (v *value) getAddr() addr { return v.addr }
 
 func (v *value) Interface() interface{} {
-	if typ, ok := v.typ.(*InterfaceType); ok {
+	typ := v.typ
+	if typ.Kind() == Interface {
 		// There are two different representations of interface values,
 		// one if the interface type has methods and one if it doesn't.
 		// These two representations require different expressions
@@ -153,16 +630,16 @@
  * basic types
  */
 
-// BoolValue represents a bool value.
-type BoolValue struct {
+// boolValue represents a bool value.
+type boolValue struct {
 	value "bool"
 }
 
 // Get returns the underlying bool value.
-func (v *BoolValue) Get() bool { return *(*bool)(v.addr) }
+func (v *boolValue) Get() bool { return *(*bool)(v.addr) }
 
 // Set sets v to the value x.
-func (v *BoolValue) Set(x bool) {
+func (v *boolValue) Set(x bool) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -170,15 +647,15 @@
 }
 
 // Set sets v to the value x.
-func (v *BoolValue) SetValue(x Value) { v.Set(x.(*BoolValue).Get()) }
+func (v *boolValue) SetValue(x Value) { v.Set(x.Bool()) }
 
-// FloatValue represents a float value.
-type FloatValue struct {
+// floatValue represents a float value.
+type floatValue struct {
 	value "float"
 }
 
 // Get returns the underlying int value.
-func (v *FloatValue) Get() float64 {
+func (v *floatValue) Get() float64 {
 	switch v.typ.Kind() {
 	case Float32:
 		return float64(*(*float32)(v.addr))
@@ -189,7 +666,7 @@
 }
 
 // Set sets v to the value x.
-func (v *FloatValue) Set(x float64) {
+func (v *floatValue) Set(x float64) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -204,7 +681,7 @@
 }
 
 // Overflow returns true if x cannot be represented by the type of v.
-func (v *FloatValue) Overflow(x float64) bool {
+func (v *floatValue) Overflow(x float64) bool {
 	if v.typ.Size() == 8 {
 		return false
 	}
@@ -215,15 +692,15 @@
 }
 
 // Set sets v to the value x.
-func (v *FloatValue) SetValue(x Value) { v.Set(x.(*FloatValue).Get()) }
+func (v *floatValue) SetValue(x Value) { v.Set(x.Float()) }
 
-// ComplexValue represents a complex value.
-type ComplexValue struct {
+// complexValue represents a complex value.
+type complexValue struct {
 	value "complex"
 }
 
 // Get returns the underlying complex value.
-func (v *ComplexValue) Get() complex128 {
+func (v *complexValue) Get() complex128 {
 	switch v.typ.Kind() {
 	case Complex64:
 		return complex128(*(*complex64)(v.addr))
@@ -234,7 +711,7 @@
 }
 
 // Set sets v to the value x.
-func (v *ComplexValue) Set(x complex128) {
+func (v *complexValue) Set(x complex128) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -248,16 +725,33 @@
 	}
 }
 
-// Set sets v to the value x.
-func (v *ComplexValue) SetValue(x Value) { v.Set(x.(*ComplexValue).Get()) }
+// How did we forget this one?
+func (v *complexValue) Overflow(x complex128) bool {
+	if v.typ.Size() == 16 {
+		return false
+	}
+	r := real(x)
+	i := imag(x)
+	if r < 0 {
+		r = -r
+	}
+	if i < 0 {
+		i = -i
+	}
+	return math.MaxFloat32 <= r && r <= math.MaxFloat64 ||
+		math.MaxFloat32 <= i && i <= math.MaxFloat64
+}
 
-// IntValue represents an int value.
-type IntValue struct {
+// Set sets v to the value x.
+func (v *complexValue) SetValue(x Value) { v.Set(x.Complex()) }
+
+// intValue represents an int value.
+type intValue struct {
 	value "int"
 }
 
 // Get returns the underlying int value.
-func (v *IntValue) Get() int64 {
+func (v *intValue) Get() int64 {
 	switch v.typ.Kind() {
 	case Int:
 		return int64(*(*int)(v.addr))
@@ -274,7 +768,7 @@
 }
 
 // Set sets v to the value x.
-func (v *IntValue) Set(x int64) {
+func (v *intValue) Set(x int64) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -295,10 +789,10 @@
 }
 
 // Set sets v to the value x.
-func (v *IntValue) SetValue(x Value) { v.Set(x.(*IntValue).Get()) }
+func (v *intValue) SetValue(x Value) { v.Set(x.Int()) }
 
 // Overflow returns true if x cannot be represented by the type of v.
-func (v *IntValue) Overflow(x int64) bool {
+func (v *intValue) Overflow(x int64) bool {
 	bitSize := uint(v.typ.Bits())
 	trunc := (x << (64 - bitSize)) >> (64 - bitSize)
 	return x != trunc
@@ -310,16 +804,16 @@
 	Len  int
 }
 
-// StringValue represents a string value.
-type StringValue struct {
+// stringValue represents a string value.
+type stringValue struct {
 	value "string"
 }
 
 // Get returns the underlying string value.
-func (v *StringValue) Get() string { return *(*string)(v.addr) }
+func (v *stringValue) Get() string { return *(*string)(v.addr) }
 
 // Set sets v to the value x.
-func (v *StringValue) Set(x string) {
+func (v *stringValue) Set(x string) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -327,15 +821,18 @@
 }
 
 // Set sets v to the value x.
-func (v *StringValue) SetValue(x Value) { v.Set(x.(*StringValue).Get()) }
+func (v *stringValue) SetValue(x Value) {
+	// Do the kind check explicitly, because x.String() does not.
+	v.Set(x.panicIfNot(String).(*stringValue).Get())
+}
 
-// UintValue represents a uint value.
-type UintValue struct {
+// uintValue represents a uint value.
+type uintValue struct {
 	value "uint"
 }
 
 // Get returns the underlying uuint value.
-func (v *UintValue) Get() uint64 {
+func (v *uintValue) Get() uint64 {
 	switch v.typ.Kind() {
 	case Uint:
 		return uint64(*(*uint)(v.addr))
@@ -354,7 +851,7 @@
 }
 
 // Set sets v to the value x.
-func (v *UintValue) Set(x uint64) {
+func (v *uintValue) Set(x uint64) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -377,17 +874,17 @@
 }
 
 // Overflow returns true if x cannot be represented by the type of v.
-func (v *UintValue) Overflow(x uint64) bool {
+func (v *uintValue) Overflow(x uint64) bool {
 	bitSize := uint(v.typ.Bits())
 	trunc := (x << (64 - bitSize)) >> (64 - bitSize)
 	return x != trunc
 }
 
 // Set sets v to the value x.
-func (v *UintValue) SetValue(x Value) { v.Set(x.(*UintValue).Get()) }
+func (v *uintValue) SetValue(x Value) { v.Set(x.Uint()) }
 
-// UnsafePointerValue represents an unsafe.Pointer value.
-type UnsafePointerValue struct {
+// unsafePointerValue represents an unsafe.Pointer value.
+type unsafePointerValue struct {
 	value "unsafe.Pointer"
 }
 
@@ -395,10 +892,10 @@
 // Get returns uintptr, not unsafe.Pointer, so that
 // programs that do not import "unsafe" cannot
 // obtain a value of unsafe.Pointer type from "reflect".
-func (v *UnsafePointerValue) Get() uintptr { return uintptr(*(*unsafe.Pointer)(v.addr)) }
+func (v *unsafePointerValue) Get() uintptr { return uintptr(*(*unsafe.Pointer)(v.addr)) }
 
 // Set sets v to the value x.
-func (v *UnsafePointerValue) Set(x unsafe.Pointer) {
+func (v *unsafePointerValue) Set(x unsafe.Pointer) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -406,8 +903,10 @@
 }
 
 // Set sets v to the value x.
-func (v *UnsafePointerValue) SetValue(x Value) {
-	v.Set(unsafe.Pointer(x.(*UnsafePointerValue).Get()))
+func (v *unsafePointerValue) SetValue(x Value) {
+	// Do the kind check explicitly, because x.UnsafePointer
+	// applies to more than just the UnsafePointer Kind.
+	v.Set(unsafe.Pointer(x.panicIfNot(UnsafePointer).(*unsafePointerValue).Get()))
 }
 
 func typesMustMatch(t1, t2 Type) {
@@ -421,9 +920,9 @@
  */
 
 // ArrayOrSliceValue is the common interface
-// implemented by both ArrayValue and SliceValue.
-type ArrayOrSliceValue interface {
-	Value
+// implemented by both arrayValue and sliceValue.
+type arrayOrSliceValue interface {
+	valueInterface
 	Len() int
 	Cap() int
 	Elem(i int) Value
@@ -432,7 +931,7 @@
 
 // grow grows the slice s so that it can hold extra more values, allocating
 // more capacity if needed. It also returns the old and new slice lengths.
-func grow(s *SliceValue, extra int) (*SliceValue, int, int) {
+func grow(s Value, extra int) (Value, int, int) {
 	i0 := s.Len()
 	i1 := i0 + extra
 	if i1 < i0 {
@@ -453,24 +952,25 @@
 			}
 		}
 	}
-	t := MakeSlice(s.Type().(*SliceType), i1, m)
+	t := MakeSlice(s.Type(), i1, m)
 	Copy(t, s)
 	return t, i0, i1
 }
 
 // Append appends the values x to a slice s and returns the resulting slice.
 // Each x must have the same type as s' element type.
-func Append(s *SliceValue, x ...Value) *SliceValue {
+func Append(s Value, x ...Value) Value {
 	s, i0, i1 := grow(s, len(x))
+	sa := s.panicIfNot(Slice).(*sliceValue)
 	for i, j := i0, 0; i < i1; i, j = i+1, j+1 {
-		s.Elem(i).SetValue(x[j])
+		sa.Elem(i).Set(x[j])
 	}
 	return s
 }
 
 // AppendSlice appends a slice t to a slice s and returns the resulting slice.
 // The slices s and t must have the same element type.
-func AppendSlice(s, t *SliceValue) *SliceValue {
+func AppendSlice(s, t Value) Value {
 	s, i0, i1 := grow(s, t.Len())
 	Copy(s.Slice(i0, i1), t)
 	return s
@@ -479,51 +979,56 @@
 // Copy copies the contents of src into dst until either
 // dst has been filled or src has been exhausted.
 // It returns the number of elements copied.
-// The arrays dst and src must have the same element type.
-func Copy(dst, src ArrayOrSliceValue) int {
+// Dst and src each must be a slice or array, and they
+// must have the same element type.
+func Copy(dst, src Value) int {
 	// TODO: This will have to move into the runtime
 	// once the real gc goes in.
-	de := dst.Type().(ArrayOrSliceType).Elem()
-	se := src.Type().(ArrayOrSliceType).Elem()
+	de := dst.Type().Elem()
+	se := src.Type().Elem()
 	typesMustMatch(de, se)
 	n := dst.Len()
 	if xn := src.Len(); n > xn {
 		n = xn
 	}
-	memmove(dst.addr(), src.addr(), uintptr(n)*de.Size())
+	memmove(dst.panicIfNots(arrayOrSlice).(arrayOrSliceValue).addr(),
+		src.panicIfNots(arrayOrSlice).(arrayOrSliceValue).addr(),
+		uintptr(n)*de.Size())
 	return n
 }
 
-// An ArrayValue represents an array.
-type ArrayValue struct {
+// An arrayValue represents an array.
+type arrayValue struct {
 	value "array"
 }
 
 // Len returns the length of the array.
-func (v *ArrayValue) Len() int { return v.typ.(*ArrayType).Len() }
+func (v *arrayValue) Len() int { return v.typ.Len() }
 
 // Cap returns the capacity of the array (equal to Len()).
-func (v *ArrayValue) Cap() int { return v.typ.(*ArrayType).Len() }
+func (v *arrayValue) Cap() int { return v.typ.Len() }
 
 // addr returns the base address of the data in the array.
-func (v *ArrayValue) addr() addr { return v.value.addr }
+func (v *arrayValue) addr() addr { return v.value.addr }
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *ArrayValue) Set(x *ArrayValue) {
+func (v *arrayValue) Set(x *arrayValue) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
 	typesMustMatch(v.typ, x.typ)
-	Copy(v, x)
+	Copy(Value{v}, Value{x})
 }
 
 // Set sets v to the value x.
-func (v *ArrayValue) SetValue(x Value) { v.Set(x.(*ArrayValue)) }
+func (v *arrayValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Array).(*arrayValue))
+}
 
 // Elem returns the i'th element of v.
-func (v *ArrayValue) Elem(i int) Value {
-	typ := v.typ.(*ArrayType).Elem()
+func (v *arrayValue) Elem(i int) Value {
+	typ := v.typ.Elem()
 	n := v.Len()
 	if i < 0 || i >= n {
 		panic("array index out of bounds")
@@ -543,28 +1048,28 @@
 	Cap  int
 }
 
-// A SliceValue represents a slice.
-type SliceValue struct {
+// A sliceValue represents a slice.
+type sliceValue struct {
 	value "slice"
 }
 
-func (v *SliceValue) slice() *SliceHeader { return (*SliceHeader)(v.value.addr) }
+func (v *sliceValue) slice() *SliceHeader { return (*SliceHeader)(v.value.addr) }
 
 // IsNil returns whether v is a nil slice.
-func (v *SliceValue) IsNil() bool { return v.slice().Data == 0 }
+func (v *sliceValue) IsNil() bool { return v.slice().Data == 0 }
 
 // Len returns the length of the slice.
-func (v *SliceValue) Len() int { return int(v.slice().Len) }
+func (v *sliceValue) Len() int { return int(v.slice().Len) }
 
 // Cap returns the capacity of the slice.
-func (v *SliceValue) Cap() int { return int(v.slice().Cap) }
+func (v *sliceValue) Cap() int { return int(v.slice().Cap) }
 
 // addr returns the base address of the data in the slice.
-func (v *SliceValue) addr() addr { return addr(v.slice().Data) }
+func (v *sliceValue) addr() addr { return addr(v.slice().Data) }
 
 // SetLen changes the length of v.
 // The new length n must be between 0 and the capacity, inclusive.
-func (v *SliceValue) SetLen(n int) {
+func (v *sliceValue) SetLen(n int) {
 	s := v.slice()
 	if n < 0 || n > int(s.Cap) {
 		panic("reflect: slice length out of range in SetLen")
@@ -574,7 +1079,7 @@
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *SliceValue) Set(x *SliceValue) {
+func (v *sliceValue) Set(x *sliceValue) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -583,23 +1088,25 @@
 }
 
 // Set sets v to the value x.
-func (v *SliceValue) SetValue(x Value) { v.Set(x.(*SliceValue)) }
+func (v *sliceValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Slice).(*sliceValue))
+}
 
 // Get returns the uintptr address of the v.Cap()'th element.  This gives
 // the same result for all slices of the same array.
 // It is mainly useful for printing.
-func (v *SliceValue) Get() uintptr {
-	typ := v.typ.(*SliceType)
+func (v *sliceValue) Get() uintptr {
+	typ := v.typ
 	return uintptr(v.addr()) + uintptr(v.Cap())*typ.Elem().Size()
 }
 
 // Slice returns a sub-slice of the slice v.
-func (v *SliceValue) Slice(beg, end int) *SliceValue {
+func (v *sliceValue) Slice(beg, end int) Value {
 	cap := v.Cap()
 	if beg < 0 || end < beg || end > cap {
 		panic("slice index out of bounds")
 	}
-	typ := v.typ.(*SliceType)
+	typ := v.typ
 	s := new(SliceHeader)
 	s.Data = uintptr(v.addr()) + uintptr(beg)*typ.Elem().Size()
 	s.Len = end - beg
@@ -611,12 +1118,12 @@
 	if v.flag&canStore != 0 {
 		flag |= canStore
 	}
-	return newValue(typ, addr(s), flag).(*SliceValue)
+	return newValue(typ, addr(s), flag)
 }
 
 // Elem returns the i'th element of v.
-func (v *SliceValue) Elem(i int) Value {
-	typ := v.typ.(*SliceType).Elem()
+func (v *sliceValue) Elem(i int) Value {
+	typ := v.typ.Elem()
 	n := v.Len()
 	if i < 0 || i >= n {
 		panic("reflect: slice index out of range")
@@ -631,30 +1138,33 @@
 
 // MakeSlice creates a new zero-initialized slice value
 // for the specified slice type, length, and capacity.
-func MakeSlice(typ *SliceType, len, cap int) *SliceValue {
+func MakeSlice(typ Type, len, cap int) Value {
+	if typ.Kind() != Slice {
+		panic("reflect: MakeSlice of non-slice type")
+	}
 	s := &SliceHeader{
 		Data: uintptr(unsafe.NewArray(typ.Elem(), cap)),
 		Len:  len,
 		Cap:  cap,
 	}
-	return newValue(typ, addr(s), canAddr|canSet|canStore).(*SliceValue)
+	return newValue(typ, addr(s), canAddr|canSet|canStore)
 }
 
 /*
  * chan
  */
 
-// A ChanValue represents a chan.
-type ChanValue struct {
+// A chanValue represents a chan.
+type chanValue struct {
 	value "chan"
 }
 
 // IsNil returns whether v is a nil channel.
-func (v *ChanValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
+func (v *chanValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *ChanValue) Set(x *ChanValue) {
+func (v *chanValue) Set(x *chanValue) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -663,11 +1173,13 @@
 }
 
 // Set sets v to the value x.
-func (v *ChanValue) SetValue(x Value) { v.Set(x.(*ChanValue)) }
+func (v *chanValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Chan).(*chanValue))
+}
 
 // Get returns the uintptr value of v.
 // It is mainly useful for printing.
-func (v *ChanValue) Get() uintptr { return *(*uintptr)(v.addr) }
+func (v *chanValue) Get() uintptr { return *(*uintptr)(v.addr) }
 
 // implemented in ../pkg/runtime/reflect.cgo
 func makechan(typ *runtime.ChanType, size uint32) (ch *byte)
@@ -678,59 +1190,59 @@
 func chancap(ch *byte) int32
 
 // Close closes the channel.
-func (v *ChanValue) Close() {
+func (v *chanValue) Close() {
 	ch := *(**byte)(v.addr)
 	chanclose(ch)
 }
 
-func (v *ChanValue) Len() int {
+func (v *chanValue) Len() int {
 	ch := *(**byte)(v.addr)
 	return int(chanlen(ch))
 }
 
-func (v *ChanValue) Cap() int {
+func (v *chanValue) Cap() int {
 	ch := *(**byte)(v.addr)
 	return int(chancap(ch))
 }
 
 // internal send; non-blocking if selected != nil
-func (v *ChanValue) send(x Value, selected *bool) {
-	t := v.Type().(*ChanType)
-	if t.Dir()&SendDir == 0 {
+func (v *chanValue) send(x Value, selected *bool) {
+	t := v.Type()
+	if t.ChanDir()&SendDir == 0 {
 		panic("send on recv-only channel")
 	}
 	typesMustMatch(t.Elem(), x.Type())
 	ch := *(**byte)(v.addr)
-	chansend(ch, (*byte)(x.getAddr()), selected)
+	chansend(ch, (*byte)(x.internal().getAddr()), selected)
 }
 
 // internal recv; non-blocking if selected != nil
-func (v *ChanValue) recv(selected *bool) (Value, bool) {
-	t := v.Type().(*ChanType)
-	if t.Dir()&RecvDir == 0 {
+func (v *chanValue) recv(selected *bool) (Value, bool) {
+	t := v.Type()
+	if t.ChanDir()&RecvDir == 0 {
 		panic("recv on send-only channel")
 	}
 	ch := *(**byte)(v.addr)
-	x := MakeZero(t.Elem())
+	x := Zero(t.Elem())
 	var ok bool
-	chanrecv(ch, (*byte)(x.getAddr()), selected, &ok)
+	chanrecv(ch, (*byte)(x.internal().getAddr()), selected, &ok)
 	return x, ok
 }
 
 // Send sends x on the channel v.
-func (v *ChanValue) Send(x Value) { v.send(x, nil) }
+func (v *chanValue) Send(x Value) { v.send(x, nil) }
 
 // Recv receives and returns a value from the channel v.
 // The receive blocks until a value is ready.
 // The boolean value ok is true if the value x corresponds to a send
 // on the channel, false if it is a zero value received because the channel is closed.
-func (v *ChanValue) Recv() (x Value, ok bool) {
+func (v *chanValue) Recv() (x Value, ok bool) {
 	return v.recv(nil)
 }
 
 // TrySend attempts to sends x on the channel v but will not block.
 // It returns true if the value was sent, false otherwise.
-func (v *ChanValue) TrySend(x Value) bool {
+func (v *chanValue) TrySend(x Value) bool {
 	var selected bool
 	v.send(x, &selected)
 	return selected
@@ -741,25 +1253,29 @@
 // If the receive can finish without blocking, TryRecv returns x != nil.
 // The boolean value ok is true if the value x corresponds to a send
 // on the channel, false if it is a zero value received because the channel is closed.
-func (v *ChanValue) TryRecv() (x Value, ok bool) {
+func (v *chanValue) TryRecv() (x Value, ok bool) {
 	var selected bool
 	x, ok = v.recv(&selected)
 	if !selected {
-		return nil, false
+		return Value{}, false
 	}
 	return x, ok
 }
 
 // MakeChan creates a new channel with the specified type and buffer size.
-func MakeChan(typ *ChanType, buffer int) *ChanValue {
+func MakeChan(typ Type, buffer int) Value {
+	if typ.Kind() != Chan {
+		panic("reflect: MakeChan of non-chan type")
+	}
 	if buffer < 0 {
 		panic("MakeChan: negative buffer size")
 	}
-	if typ.Dir() != BothDir {
+	if typ.ChanDir() != BothDir {
 		panic("MakeChan: unidirectional channel type")
 	}
-	v := MakeZero(typ).(*ChanValue)
-	*(**byte)(v.addr) = makechan((*runtime.ChanType)(unsafe.Pointer(typ)), uint32(buffer))
+	v := Zero(typ)
+	ch := v.panicIfNot(Chan).(*chanValue)
+	*(**byte)(ch.addr) = makechan((*runtime.ChanType)(unsafe.Pointer(typ.(*commonType))), uint32(buffer))
 	return v
 }
 
@@ -767,23 +1283,23 @@
  * func
  */
 
-// A FuncValue represents a function value.
-type FuncValue struct {
+// A funcValue represents a function value.
+type funcValue struct {
 	value       "func"
 	first       *value
 	isInterface bool
 }
 
 // IsNil returns whether v is a nil function.
-func (v *FuncValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
+func (v *funcValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
 
 // Get returns the uintptr value of v.
 // It is mainly useful for printing.
-func (v *FuncValue) Get() uintptr { return *(*uintptr)(v.addr) }
+func (v *funcValue) Get() uintptr { return *(*uintptr)(v.addr) }
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *FuncValue) Set(x *FuncValue) {
+func (v *funcValue) Set(x *funcValue) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -792,21 +1308,23 @@
 }
 
 // Set sets v to the value x.
-func (v *FuncValue) SetValue(x Value) { v.Set(x.(*FuncValue)) }
+func (v *funcValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Func).(*funcValue))
+}
 
-// Method returns a FuncValue corresponding to v's i'th method.
-// The arguments to a Call on the returned FuncValue
-// should not include a receiver; the FuncValue will use v
+// Method returns a funcValue corresponding to v's i'th method.
+// The arguments to a Call on the returned funcValue
+// should not include a receiver; the funcValue will use v
 // as the receiver.
-func (v *value) Method(i int) *FuncValue {
+func (v *value) Method(i int) Value {
 	t := v.Type().uncommon()
 	if t == nil || i < 0 || i >= len(t.methods) {
-		return nil
+		panic("reflect: Method index out of range")
 	}
 	p := &t.methods[i]
 	fn := p.tfn
-	fv := &FuncValue{value: value{toType(*p.typ), addr(&fn), 0}, first: v, isInterface: false}
-	return fv
+	fv := &funcValue{value: value{toType(p.typ), addr(&fn), 0}, first: v, isInterface: false}
+	return Value{fv}
 }
 
 // implemented in ../pkg/runtime/*/asm.s
@@ -820,23 +1338,23 @@
 // If fv is a method obtained by invoking Value.Method
 // (as opposed to Type.Method), Interface cannot return an
 // interface value, so it panics.
-func (fv *FuncValue) Interface() interface{} {
+func (fv *funcValue) Interface() interface{} {
 	if fv.first != nil {
-		panic("FuncValue: cannot create interface value for method with bound receiver")
+		panic("funcValue: cannot create interface value for method with bound receiver")
 	}
 	return fv.value.Interface()
 }
 
 // Call calls the function fv with input parameters in.
 // It returns the function's output parameters as Values.
-func (fv *FuncValue) Call(in []Value) []Value {
-	t := fv.Type().(*FuncType)
+func (fv *funcValue) Call(in []Value) []Value {
+	t := fv.Type()
 	nin := len(in)
 	if fv.first != nil && !fv.isInterface {
 		nin++
 	}
 	if nin != t.NumIn() {
-		panic("FuncValue: wrong argument count")
+		panic("funcValue: wrong argument count")
 	}
 	nout := t.NumOut()
 
@@ -906,7 +1424,7 @@
 		a := uintptr(tv.Align())
 		off = (off + a - 1) &^ (a - 1)
 		n := tv.Size()
-		memmove(addr(ptr+off), v.getAddr(), n)
+		memmove(addr(ptr+off), v.internal().getAddr(), n)
 		off += n
 	}
 	off = (off + ptrSize - 1) &^ (ptrSize - 1)
@@ -922,9 +1440,9 @@
 		tv := t.Out(i)
 		a := uintptr(tv.Align())
 		off = (off + a - 1) &^ (a - 1)
-		v := MakeZero(tv)
+		v := Zero(tv)
 		n := tv.Size()
-		memmove(v.getAddr(), addr(ptr+off), n)
+		memmove(v.internal().getAddr(), addr(ptr+off), n)
 		ret[i] = v
 		off += n
 	}
@@ -936,40 +1454,37 @@
  * interface
  */
 
-// An InterfaceValue represents an interface value.
-type InterfaceValue struct {
+// An interfaceValue represents an interface value.
+type interfaceValue struct {
 	value "interface"
 }
 
 // IsNil returns whether v is a nil interface value.
-func (v *InterfaceValue) IsNil() bool { return v.Interface() == nil }
+func (v *interfaceValue) IsNil() bool { return v.Interface() == nil }
 
 // No single uinptr Get because v.Interface() is available.
 
 // Get returns the two words that represent an interface in the runtime.
 // Those words are useful only when playing unsafe games.
-func (v *InterfaceValue) Get() [2]uintptr {
+func (v *interfaceValue) Get() [2]uintptr {
 	return *(*[2]uintptr)(v.addr)
 }
 
 // Elem returns the concrete value stored in the interface value v.
-func (v *InterfaceValue) Elem() Value { return NewValue(v.Interface()) }
+func (v *interfaceValue) Elem() Value { return NewValue(v.Interface()) }
 
 // ../runtime/reflect.cgo
-func setiface(typ *InterfaceType, x *interface{}, addr addr)
+func setiface(typ *interfaceType, x *interface{}, addr addr)
 
 // Set assigns x to v.
-func (v *InterfaceValue) Set(x Value) {
-	var i interface{}
-	if x != nil {
-		i = x.Interface()
-	}
+func (v *interfaceValue) Set(x Value) {
+	i := x.Interface()
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
 	// Two different representations; see comment in Get.
 	// Empty interface is easy.
-	t := v.typ.(*InterfaceType)
+	t := (*interfaceType)(unsafe.Pointer(v.typ.(*commonType)))
 	if t.NumMethod() == 0 {
 		*(*interface{})(v.addr) = i
 		return
@@ -980,16 +1495,16 @@
 }
 
 // Set sets v to the value x.
-func (v *InterfaceValue) SetValue(x Value) { v.Set(x) }
+func (v *interfaceValue) SetValue(x Value) { v.Set(x) }
 
-// Method returns a FuncValue corresponding to v's i'th method.
-// The arguments to a Call on the returned FuncValue
-// should not include a receiver; the FuncValue will use v
+// Method returns a funcValue corresponding to v's i'th method.
+// The arguments to a Call on the returned funcValue
+// should not include a receiver; the funcValue will use v
 // as the receiver.
-func (v *InterfaceValue) Method(i int) *FuncValue {
-	t := v.Type().(*InterfaceType)
+func (v *interfaceValue) Method(i int) Value {
+	t := (*interfaceType)(unsafe.Pointer(v.Type().(*commonType)))
 	if t == nil || i < 0 || i >= len(t.methods) {
-		return nil
+		panic("reflect: Method index out of range")
 	}
 	p := &t.methods[i]
 
@@ -999,25 +1514,25 @@
 
 	// Function pointer is at p.perm in the table.
 	fn := tab.Fn[i]
-	fv := &FuncValue{value: value{toType(*p.typ), addr(&fn), 0}, first: data, isInterface: true}
-	return fv
+	fv := &funcValue{value: value{toType(p.typ), addr(&fn), 0}, first: data, isInterface: true}
+	return Value{fv}
 }
 
 /*
  * map
  */
 
-// A MapValue represents a map value.
-type MapValue struct {
+// A mapValue represents a map value.
+type mapValue struct {
 	value "map"
 }
 
 // IsNil returns whether v is a nil map value.
-func (v *MapValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
+func (v *mapValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *MapValue) Set(x *MapValue) {
+func (v *mapValue) Set(x *mapValue) {
 	if !v.CanSet() {
 		panic(cannotSet)
 	}
@@ -1030,17 +1545,13 @@
 }
 
 // Set sets v to the value x.
-func (v *MapValue) SetValue(x Value) {
-	if x == nil {
-		v.Set(nil)
-		return
-	}
-	v.Set(x.(*MapValue))
+func (v *mapValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Map).(*mapValue))
 }
 
 // Get returns the uintptr value of v.
 // It is mainly useful for printing.
-func (v *MapValue) Get() uintptr { return *(*uintptr)(v.addr) }
+func (v *mapValue) Get() uintptr { return *(*uintptr)(v.addr) }
 
 // implemented in ../pkg/runtime/reflect.cgo
 func mapaccess(m, key, val *byte) bool
@@ -1053,36 +1564,36 @@
 
 // Elem returns the value associated with key in the map v.
 // It returns nil if key is not found in the map.
-func (v *MapValue) Elem(key Value) Value {
-	t := v.Type().(*MapType)
+func (v *mapValue) Elem(key Value) Value {
+	t := v.Type()
 	typesMustMatch(t.Key(), key.Type())
 	m := *(**byte)(v.addr)
 	if m == nil {
-		return nil
+		return Value{}
 	}
-	newval := MakeZero(t.Elem())
-	if !mapaccess(m, (*byte)(key.getAddr()), (*byte)(newval.getAddr())) {
-		return nil
+	newval := Zero(t.Elem())
+	if !mapaccess(m, (*byte)(key.internal().getAddr()), (*byte)(newval.internal().getAddr())) {
+		return Value{}
 	}
 	return newval
 }
 
 // SetElem sets the value associated with key in the map v to val.
 // If val is nil, Put deletes the key from map.
-func (v *MapValue) SetElem(key, val Value) {
-	t := v.Type().(*MapType)
+func (v *mapValue) SetElem(key, val Value) {
+	t := v.Type()
 	typesMustMatch(t.Key(), key.Type())
 	var vaddr *byte
-	if val != nil {
+	if val.IsValid() {
 		typesMustMatch(t.Elem(), val.Type())
-		vaddr = (*byte)(val.getAddr())
+		vaddr = (*byte)(val.internal().getAddr())
 	}
 	m := *(**byte)(v.addr)
-	mapassign(m, (*byte)(key.getAddr()), vaddr)
+	mapassign(m, (*byte)(key.internal().getAddr()), vaddr)
 }
 
 // Len returns the number of keys in the map v.
-func (v *MapValue) Len() int {
+func (v *mapValue) Len() int {
 	m := *(**byte)(v.addr)
 	if m == nil {
 		return 0
@@ -1092,8 +1603,8 @@
 
 // Keys returns a slice containing all the keys present in the map,
 // in unspecified order.
-func (v *MapValue) Keys() []Value {
-	tk := v.Type().(*MapType).Key()
+func (v *mapValue) Keys() []Value {
+	tk := v.Type().Key()
 	m := *(**byte)(v.addr)
 	mlen := int32(0)
 	if m != nil {
@@ -1103,8 +1614,8 @@
 	a := make([]Value, mlen)
 	var i int
 	for i = 0; i < len(a); i++ {
-		k := MakeZero(tk)
-		if !mapiterkey(it, (*byte)(k.getAddr())) {
+		k := Zero(tk)
+		if !mapiterkey(it, (*byte)(k.internal().getAddr())) {
 			break
 		}
 		a[i] = k
@@ -1114,9 +1625,13 @@
 }
 
 // MakeMap creates a new map of the specified type.
-func MakeMap(typ *MapType) *MapValue {
-	v := MakeZero(typ).(*MapValue)
-	*(**byte)(v.addr) = makemap((*runtime.MapType)(unsafe.Pointer(typ)))
+func MakeMap(typ Type) Value {
+	if typ.Kind() != Map {
+		panic("reflect: MakeMap of non-map type")
+	}
+	v := Zero(typ)
+	m := v.panicIfNot(Map).(*mapValue)
+	*(**byte)(m.addr) = makemap((*runtime.MapType)(unsafe.Pointer(typ.(*commonType))))
 	return v
 }
 
@@ -1124,21 +1639,21 @@
  * ptr
  */
 
-// A PtrValue represents a pointer.
-type PtrValue struct {
+// A ptrValue represents a pointer.
+type ptrValue struct {
 	value "ptr"
 }
 
 // IsNil returns whether v is a nil pointer.
-func (v *PtrValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
+func (v *ptrValue) IsNil() bool { return *(*uintptr)(v.addr) == 0 }
 
 // Get returns the uintptr value of v.
 // It is mainly useful for printing.
-func (v *PtrValue) Get() uintptr { return *(*uintptr)(v.addr) }
+func (v *ptrValue) Get() uintptr { return *(*uintptr)(v.addr) }
 
 // Set assigns x to v.
 // The new value x must have the same type as v, and x.Elem().CanSet() must be true.
-func (v *PtrValue) Set(x *PtrValue) {
+func (v *ptrValue) Set(x *ptrValue) {
 	if x == nil {
 		*(**uintptr)(v.addr) = nil
 		return
@@ -1156,25 +1671,21 @@
 }
 
 // Set sets v to the value x.
-func (v *PtrValue) SetValue(x Value) {
-	if x == nil {
-		v.Set(nil)
-		return
-	}
-	v.Set(x.(*PtrValue))
+func (v *ptrValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Ptr).(*ptrValue))
 }
 
 // PointTo changes v to point to x.
 // If x is a nil Value, PointTo sets v to nil.
-func (v *PtrValue) PointTo(x Value) {
-	if x == nil {
+func (v *ptrValue) PointTo(x Value) {
+	if !x.IsValid() {
 		*(**uintptr)(v.addr) = nil
 		return
 	}
 	if !x.CanSet() {
 		panic("cannot set x; cannot point to x")
 	}
-	typesMustMatch(v.typ.(*PtrType).Elem(), x.Type())
+	typesMustMatch(v.typ.Elem(), x.Type())
 	// TODO: This will have to move into the runtime
 	// once the new gc goes in.
 	*(*uintptr)(v.addr) = x.UnsafeAddr()
@@ -1182,39 +1693,39 @@
 
 // Elem returns the value that v points to.
 // If v is a nil pointer, Elem returns a nil Value.
-func (v *PtrValue) Elem() Value {
+func (v *ptrValue) Elem() Value {
 	if v.IsNil() {
-		return nil
+		return Value{}
 	}
 	flag := canAddr
 	if v.flag&canStore != 0 {
 		flag |= canSet | canStore
 	}
-	return newValue(v.typ.(*PtrType).Elem(), *(*addr)(v.addr), flag)
+	return newValue(v.typ.Elem(), *(*addr)(v.addr), flag)
 }
 
 // Indirect returns the value that v points to.
 // If v is a nil pointer, Indirect returns a nil Value.
 // If v is not a pointer, Indirect returns v.
 func Indirect(v Value) Value {
-	if pv, ok := v.(*PtrValue); ok {
-		return pv.Elem()
+	if v.Kind() != Ptr {
+		return v
 	}
-	return v
+	return v.panicIfNot(Ptr).(*ptrValue).Elem()
 }
 
 /*
  * struct
  */
 
-// A StructValue represents a struct value.
-type StructValue struct {
+// A structValue represents a struct value.
+type structValue struct {
 	value "struct"
 }
 
 // Set assigns x to v.
 // The new value x must have the same type as v.
-func (v *StructValue) Set(x *StructValue) {
+func (v *structValue) Set(x *structValue) {
 	// TODO: This will have to move into the runtime
 	// once the gc goes in.
 	if !v.CanSet() {
@@ -1225,13 +1736,15 @@
 }
 
 // Set sets v to the value x.
-func (v *StructValue) SetValue(x Value) { v.Set(x.(*StructValue)) }
+func (v *structValue) SetValue(x Value) {
+	v.Set(x.panicIfNot(Struct).(*structValue))
+}
 
 // Field returns the i'th field of the struct.
-func (v *StructValue) Field(i int) Value {
-	t := v.typ.(*StructType)
+func (v *structValue) Field(i int) Value {
+	t := v.typ
 	if i < 0 || i >= t.NumField() {
-		return nil
+		panic("reflect: Field index out of range")
 	}
 	f := t.Field(i)
 	flag := v.flag
@@ -1243,102 +1756,102 @@
 }
 
 // FieldByIndex returns the nested field corresponding to index.
-func (t *StructValue) FieldByIndex(index []int) (v Value) {
-	v = t
+func (t *structValue) FieldByIndex(index []int) (v Value) {
+	v = Value{t}
 	for i, x := range index {
 		if i > 0 {
-			if p, ok := v.(*PtrValue); ok {
-				v = p.Elem()
+			if v.Kind() == Ptr {
+				v = v.Elem()
 			}
-			if s, ok := v.(*StructValue); ok {
-				t = s
-			} else {
-				v = nil
-				return
+			if v.Kind() != Struct {
+				return Value{}
 			}
 		}
-		v = t.Field(x)
+		v = v.Field(x)
 	}
 	return
 }
 
 // FieldByName returns the struct field with the given name.
 // The result is nil if no field was found.
-func (t *StructValue) FieldByName(name string) Value {
-	if f, ok := t.Type().(*StructType).FieldByName(name); ok {
+func (t *structValue) FieldByName(name string) Value {
+	if f, ok := t.Type().FieldByName(name); ok {
 		return t.FieldByIndex(f.Index)
 	}
-	return nil
+	return Value{}
 }
 
 // FieldByNameFunc returns the struct field with a name that satisfies the
 // match function.
 // The result is nil if no field was found.
-func (t *StructValue) FieldByNameFunc(match func(string) bool) Value {
-	if f, ok := t.Type().(*StructType).FieldByNameFunc(match); ok {
+func (t *structValue) FieldByNameFunc(match func(string) bool) Value {
+	if f, ok := t.Type().FieldByNameFunc(match); ok {
 		return t.FieldByIndex(f.Index)
 	}
-	return nil
+	return Value{}
 }
 
 // NumField returns the number of fields in the struct.
-func (v *StructValue) NumField() int { return v.typ.(*StructType).NumField() }
+func (v *structValue) NumField() int { return v.typ.NumField() }
 
 /*
  * constructors
  */
 
 // NewValue returns a new Value initialized to the concrete value
-// stored in the interface i.  NewValue(nil) returns nil.
+// stored in the interface i.  NewValue(nil) returns the zero Value.
 func NewValue(i interface{}) Value {
 	if i == nil {
-		return nil
+		return Value{}
 	}
-	t, a := unsafe.Reflect(i)
-	return newValue(toType(t), addr(a), canSet|canAddr|canStore)
+	_, a := unsafe.Reflect(i)
+	return newValue(Typeof(i), addr(a), canSet|canAddr|canStore)
 }
 
 func newValue(typ Type, addr addr, flag uint32) Value {
 	v := value{typ, addr, flag}
-	switch typ.(type) {
-	case *ArrayType:
-		return &ArrayValue{v}
-	case *BoolType:
-		return &BoolValue{v}
-	case *ChanType:
-		return &ChanValue{v}
-	case *FloatType:
-		return &FloatValue{v}
-	case *FuncType:
-		return &FuncValue{value: v}
-	case *ComplexType:
-		return &ComplexValue{v}
-	case *IntType:
-		return &IntValue{v}
-	case *InterfaceType:
-		return &InterfaceValue{v}
-	case *MapType:
-		return &MapValue{v}
-	case *PtrType:
-		return &PtrValue{v}
-	case *SliceType:
-		return &SliceValue{v}
-	case *StringType:
-		return &StringValue{v}
-	case *StructType:
-		return &StructValue{v}
-	case *UintType:
-		return &UintValue{v}
-	case *UnsafePointerType:
-		return &UnsafePointerValue{v}
+	switch typ.Kind() {
+	case Array:
+		return Value{&arrayValue{v}}
+	case Bool:
+		return Value{&boolValue{v}}
+	case Chan:
+		return Value{&chanValue{v}}
+	case Float32, Float64:
+		return Value{&floatValue{v}}
+	case Func:
+		return Value{&funcValue{value: v}}
+	case Complex64, Complex128:
+		return Value{&complexValue{v}}
+	case Int, Int8, Int16, Int32, Int64:
+		return Value{&intValue{v}}
+	case Interface:
+		return Value{&interfaceValue{v}}
+	case Map:
+		return Value{&mapValue{v}}
+	case Ptr:
+		return Value{&ptrValue{v}}
+	case Slice:
+		return Value{&sliceValue{v}}
+	case String:
+		return Value{&stringValue{v}}
+	case Struct:
+		return Value{&structValue{v}}
+	case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+		return Value{&uintValue{v}}
+	case UnsafePointer:
+		return Value{&unsafePointerValue{v}}
 	}
 	panic("newValue" + typ.String())
 }
 
-// MakeZero returns a zero Value for the specified Type.
-func MakeZero(typ Type) Value {
+// Zero returns a Value representing a zero value for the specified type.
+// The result is different from the zero value of the Value struct,
+// which represents no value at all.
+// For example, Zero(Typeof(42)) returns a Value with Kind Int and value 0.
+func Zero(typ Type) Value {
 	if typ == nil {
-		return nil
+		panic("reflect: Zero(nil)")
 	}
 	return newValue(typ, addr(unsafe.New(typ)), canSet|canAddr|canStore)
 }