| name | go-idioms |
| description | Modern idiomatic Go (the `modernize` analyzer set). This skill should be used when the user writes, reviews, or modernizes Go and wants current-version idioms — range-over-int, `min`/`max`, `slices`/`maps`, `strings.Cut`, `cmp.Or`, `sync.OnceFunc`, iterators, `slog.LogAttrs`, `new(expr)` (Go 1.26), dropped loop-var copies. Framed so advice equals tooling (`go fix ./...` on Go 1.26, or `golangci-lint --enable-only=modernize`). Errors→`go-errors`, concurrency→`go-concurrency`, tests→`go-testing`. Not for golangci-lint configuration (use `go-linting`) or non-Go languages. |
go-idioms — modern Go (modernize)
Advice == tooling. The modernize analyzers flag and usually auto-fix everything below. Run
them, don't hand-audit. As of Go 1.26 the rewritten go fix is the canonical runner — it ships
the full modernizer suite in the toolchain itself:
go fix ./... # Go 1.26+: applies the built-in modernizers
golangci-lint run --enable-only=modernize --fix # any toolchain (same analyzers, via golangci-lint)
Both draw on the same golang.org/x/tools engine as gopls, so their fixes agree. This skill
explains why and catches what review notices before the tool runs. Check go.mod first —
gate each idiom on the module's Go version (the Since column below); don't apply a Go 1.26 idiom to
a repo pinned to 1.25 or older.
Prefer → over (since)
| Prefer | Over | Since |
|---|
new(expr) — e.g. Field: new(30), new(int64(req.Limit)) | a ptr[T](v) helper (auto-rewritten by the newexpr fixer) or a hand-written tmp := v; &tmp, for optional/pointer fields | 1.26 |
for i := range n | for i := 0; i < n; i++ | 1.22 |
min(a, b) / max(a, b) builtins | hand-rolled helpers | 1.21 |
(drop) x := x loop-var copy | pre-1.22 capture workaround | 1.22 |
slices.Sort/Contains/Equal, slices.Collect, maps.Keys | hand-rolled sort/contains/dedup | 1.21–1.23 |
strings.Cut / CutPrefix / CutSuffix | Index + manual slicing | 1.18/1.20 |
cmp.Or(a, b, …) | nested if x == "" { x = y } | 1.22 |
sync.OnceFunc / OnceValue | sync.Once + a captured var | 1.21 |
iter.Seq[V] / range-over-func | Visit(callback) patterns, exposing slices | 1.23 |
slog.LogAttrs(ctx, lvl, msg, attrs…) on hot paths | key-value variadic slog (allocates) | 1.21 |
errors.Join | manual multi-error concat → go-errors | 1.20 |
wg.Go(...) | wg.Add(1)/defer wg.Done() → go-concurrency | 1.25 |
for b.Loop() | for i := 0; i < b.N; i++ → go-testing | 1.24 |
typed atomic.Int64 | bare-int atomic.Add* → go-concurrency | 1.19 |
Idioms are a moving target — let the tool (pinned to the repo's toolchain) be the source of
truth so advice never drifts from the user's go fix. Go 1.26 also lifts the ban on a generic type
referencing itself in its own type-parameter list (e.g. type Adder[A Adder[A]] interface{ Add(A) A }),
so self-referential constraints no longer need a workaround — but that's a hand-written pattern, not
something a modernizer rewrites.
Sources
Decomposition inspired by samber/cc-skills-golang (MIT © 2026 Samuel Berthe); rules grounded in the sources above.
