Comment by foldr
11 hours ago
Go lets you constrain type parameters with interfaces. To do anything analagous in SML you have to use functors, which is substantially less convenient. I think people who refer to ML's parametric polymorphism in this context must really be thinking of parametric polymorphism in OCaml or Haskell.
You just do dictionary passing.
Like this, you mean? https://haskellforall.com/2012/05/scrap-your-type-classes
Fine in principle, but AFAIK it never really caught on because the ergonomics suck. Interfaces/traits/type classes do seem to be a popular feature across languages, for what it's worth.