Go 1.17 was recently released, per the
“release twice a year”
schedule. As always, there’s a bunch of commentators noting that it still
doesn’t have generics yet (it’s a work in
progress and there’s a lot of work).
Sometimes this is expressed as if Go code must therefore be littered with
numerous uses of the empty interface{} type.
Here’s one counter-anecdote, where interface{} just isn’t that frequent,
whether that’s “interface{} approximating generics” or otherwise. The Wuffs
codebase is about 60k lines of Go code. Even
after accounting that about 25% of that is a
generated data
table (the Wuffs compiler’s pre-parsed equivalent of
arm_neon.h),
it’s still not a small or toy set of programs:
$ git show | head -n 1
commit 1d191576683c97e8e3c59258f7dca9a010a10754
$ find . -name *.go | xargs wc -l | tail -n 1
60106 total
$ wc -l lib/armneonintrinsics/data.go
16713 lib/armneonintrinsics/data.go
In that whole corpus, interface{} is only used three times.
$ rg 'interface\{\}'
script/print-crc32-x86-sse42-magic-numbers.go
69:func debugf(format string, a ...interface{}) {
script/print-file-sizes-json.go
100:type dir map[string]interface{}
internal/cgen/cgen.go
232:func (b *buffer) printf(format string, args ...interface{}) { fmt.Fprintf(b, format, args...) }
Two of those three simply mimic the
fmt.Printf signature, whose arguments can
indeed have varied types.
The last one, in a 99 line
program,
admittedly does use interface{} where other languages would use some sort of
type-safe enum or union. But I don’t think generics would change anything here.
In a similar vein, this repository full of Go code also doesn’t use reflection
at all, other than a couple of
reflect.DeepEqual calls in tests:
$ find . -name *.go | xargs rg -w reflect
./lang/check/check_test.go
21: "reflect"
167: if !reflect.DeepEqual(got, want) {
./lib/compression/compression_test.go
18: "reflect"
35: if !reflect.DeepEqual(got, want) {
In conclusion, yes, generics are useful, and plenty of people want them in Go, for good reason. But you can also still get plenty done in Go without them.
Published: 2021-08-22