Thanks for this. By coincidence, I was sketching out a polymorphism kludge this evening, and this was food for thought.

That reminds me very strongly how Zig does it

I'm not familiar with Zig, but a quick look at https://ziglang.org/documentation/master/#Generic-Data-Struc... makes me doubt that Zig does genericity on module level; looks rather like parametric polymorphism.

Not GP, and I'm just surfing unfamiliar docs, but it looks like, yes, there's general parameter polymorphism,[1] but also "modules" presented as structs,[2] and the polymorphism of struct constructors can have nontrivial impacts[3](eg Map(KeyType,void) loses value setters). Fwiw.

[1] https://ziglang.org/documentation/master/#comptime "Compile-time parameters is how Zig implements generics. It is compile-time duck typing." [2] https://ziglang.org/documentation/master/#import [3] https://ziglang.org/documentation/master/#void "By using void as the type of the value, the hash map entry type has no value field, and thus the hash map takes up less space. Further, all the code that deals with storing and loading the value is deleted, as seen above."

interesting, thanks