Opening ADT constructor as a module

[ppolesiuk]

A module could be passed as a named parameter to ADT constructor pattern. Such a construct would define a new local module containing all named parameters. The motivating example is to use encode kind of generative functors known from OCaml or SML, using just named parameters.

data Map Key = Map
  { T
  , empty : {Val} ->[] T Val
  , method add : {Val} -> T Val -> Key -> Val ->[] T Val
  , method find : {Val} -> T Val -> Key ->[] Option Val
  }

(* Functor-like function *)
let makeMap {Key} (compare : Key -> Key ->[] Ord) =
  Map { ... }

(* Functor-like application: creating a new module StrMap that implements maps *)
let (Map { module StrMap }) = make String.compare