_content/tour/generics.article

Generics
Go supports generic programming using type parameters. This lesson shows some examples for employing generics in your code.

The Go Authors
https://golang.org

* Type parameters

Go functions can be written to work on multiple types using type parameters. The
type parameters of a function appear between brackets, before the function's
arguments.

  func Index[T comparable](s []T, x T) int

This declaration means that `s` is a slice of any type `T` that fulfills the
built-in constraint `comparable`. `x` is also a value of the same type.

`comparable` is a useful constraint that makes it possible to use the `==` and
`!=` operators on values of the type. In this example, we use it to compare a
value to all slice elements until a match is found. This `Index` function works
for any type that supports comparison.

.play generics/index.go

* Generic types

In addition to generic functions, Go also supports generic types. A type can
be parameterized with a type parameter, which could be useful for implementing
generic data structures.

This example demonstrates a simple type declaration for a singly-linked list
holding any type of value.

As an exercise, add some functionality to this list implementation.

.play generics/list.go

* Congratulations!

You finished this lesson!

You can go back to the list of [[/tour/list][modules]] to find what to learn next, or continue with the [[javascript:click('.next-page')][next lesson]].