[maxiepoo]

Sure but it's worth emphasizing that Go language designers gave these built-in collections the exorbitant privilege of being parameterized by a type and declaring that any new type created by a mere programmer has to be monomorphic.

[foldr]

> the exorbitant privilege of being parameterized by a type

This is how built in collection types work in pretty much all statically typed languages. For example, here is an array of ints in C:

    int foo[] = { 1, 2, 3 };

We wouldn't usually say that C has 'generic arrays'.

> any new type created by a mere programmer has to be monomorphic.

Collections in (pre-Generics) Go are monomorphic. []foo and []bar are as different as foo and bar. That is why, for example, the first argument of sort.Slice has type 'any' (https://cs.opensource.google/go/go/+/go1.18.2:src/sort/slice...)