slog: rethink levels

We want the default level to be Info, so make it zero.

Then rejigger the level numbers to match OpenTelemetry:
- Reverse the direction, so larger numbers are more severe.
- Reduce the gaps between named levels from 10 to 4.

There is still a nice mapping to verbosities: negation.

By making the zero level valid, we lose a level value that means "no
level." We could reinstate it by picking an extreme value,
like math.MinInt. Or we could just omit it; perhaps it's
not needed.

Change-Id: I0f06418b7de79fde0c172e5c9d88c707fac74601
Reviewed-on: https://go-review.googlesource.com/c/exp/+/435896
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
5 files changed
tree: 81591486bebf34bb5d0517b951683f12c98d0a67
  1. apidiff/
  2. cmd/
  3. constraints/
  4. devtools/
  5. ebnf/
  6. ebnflint/
  7. errors/
  8. event/
  9. inotify/
  10. io/
  11. jsonrpc2/
  12. maps/
  13. mmap/
  14. rand/
  15. shiny/
  16. shootout/
  17. slices/
  18. slog/
  19. sumdb/
  20. typeparams/
  21. utf8string/
  22. .gitattributes
  23. .gitignore
  24. codereview.cfg
  25. CONTRIBUTING.md
  26. go.mod
  27. go.sum
  28. LICENSE
  29. PATENTS
  30. README.md
README.md

exp

PkgGoDev

This subrepository holds experimental and deprecated (in the old directory) packages.

The idea for this subrepository originated as the pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to go get these packages.

Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.

In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)

Caveat emptor.