[silisili]

Slices are passed only by value. It's just that the value is a struct containing a reference to the data. Once one understands that, the rest makes perfect sense.

I can see why it trips up newcomers, but it feels pretty basic otherwise.

[lsaferite]

I say this as someone working with go every day.

The fact that I can pass a slice to a func 'by value' and mutate the source slice outside the func is already surprising behavior to most people. The fact that it MIGHT mutate the source slice depending on the slice capacity is the part that really drives it home as bad ergonomics for me.

Overall I enjoy working with go, but there are a few aspects that drive me up the wall, this is one of them.

[silisili]

How would you have designed it? An internal byte array instead of a pointer?

[TheDong]

I think the key thing missing from go slices is ownership information, especially around sub-slices.

Make it so you can create copy-on-write slices of a larger slice, and a huge number of bugs go away.

Or do what rust did, except at runtime, and keep track of ownership

    s := []int{1, 2, 3}
    s[0] = 0 // fine, s owns data
    s1 := s[0:2] // ownership transferred to s1, s is now read-only
    s1[0] = 1 // fine, s1 owns data

    s[0] = 1 // panic or compiler error, s1 owns data, not s

With of course functions to allow multiple mutable ownership in cases where that's needed, but it shouldn't be the default