[masklinn]

Go doesn’t have reference types, and slices certainly do not behave like them: because the slice is composed of the pointer, length, and capacity (on the stack) if you want to modify a slice on behalf of a caller you absolutely must get a pointer to a slice, unless your mutations consist solely of setting existing indices.

Go’s map is (AFAIK) a pointer to the hmap stucture where everything happens, so it does behave like a reference type (all updates in the callee will be visible to the caller) but even then it can be useful to have a pointer to one so you can reset it without mutating it in-place. While that can be a bit weirder, it is also much safer. Especially given Go’s maps are not thread-safe (and in fact not memory-safe under concurrent updates).

[ratorx]

Isn’t passing in pointers to slices considered an anti-pattern? I thought the go way would be to take the slice as argument by value and return possibly a different slice, like append does. I don’t think I’ve seen any (idiomatic) code that took slices by pointer.