import { makeGeneric } from "../generics/generics.js";
import { Type } from "../type.js";
import { typedFnType } from "./types.js";
import { prodType } from "./types.js";

// In JS, all products are encoded in the same way:
const constructor = left => right => ({left, right});
const getLeft     = product => product.left;
const getRight    = product => product.right;

export const ModuleProduct = {l: [
  // binary type constructor
  // Type -> Type -> Type
  ...typedFnType(prodType, fnType =>
    fnType
      (Type)
      (fnType
        (Type)
        (Type)
      )
  ),

  // a -> b -> (a, b)
  ...typedFnType(constructor, fnType =>
    makeGeneric((a, b) =>
      fnType
        (a)
        (fnType
          (b)
          (prodType(a)(b))
        )
    )),

  // (a, b) -> a
  ...typedFnType(getLeft, fnType =>
    makeGeneric((a, b) =>
      fnType
        (prodType(a)(b))
        (a)
    )),

  // (a, b) -> b
  ...typedFnType(getRight, fnType =>
    makeGeneric((a, b) =>
      fnType
        (prodType(a)(b))
        (b)
    )),
]};