import { Bool, Int } from "../primitives/types.js";
import { fnType, lsType } from "../structures/types.js";
import { assign, makeGeneric, unify } from "../generics/generics.js";
import { prettyGenT, prettyT } from "../util/pretty.js";

// a -> Int
const a_to_Int = makeGeneric(a => fnType(() => a)(() => Int));
console.log((prettyGenT(a_to_Int))); // ∀a: (a -> Int)
// Bool -> Int
const Bool_to_Int = makeGeneric(() => fnType(() => lsType(() =>Bool))(() => Int));
console.log((prettyGenT(Bool_to_Int))); // ∀: ([Bool] -> Int)
console.log("should be: [Bool] -> Int")
console.log(prettyGenT(unify(a_to_Int, Bool_to_Int)));

// (a -> a) -> b
const fnType2 = makeGeneric((a,b) => fnType(() => fnType(a)(a))(() => b));
// (Bool -> Bool) -> a
const fnType3 = makeGeneric(a => fnType(() => fnType(Bool)(Bool))(() => a));
console.log("should be: (Bool -> Bool) -> a");
console.log(prettyT(unify(fnType2, fnType3)));

// (a -> b) -> [a] -> [b]
const mapFnType = makeGeneric((a,b) =>
  fnType
    (fnType(() => a)(() => b))
    (fnType(() => lsType(() =>a))(() => lsType(() =>b))))
// a -> a
const idFnType = makeGeneric((_,__,c) =>
  fnType(() => c)(() => c));
console.log("should be: [c] -> [c]");
console.log(prettyT(assign(mapFnType, idFnType)));

// (a -> Int) -> [a] -> a
const weirdFnType = makeGeneric(a =>
  fnType
    (fnType(() => a)(() => Int))
    (fnType
      (lsType(() =>a))
      (a)))
// we call this function with parameter of type (b -> b) ...
// giving these substitutions:
//    a := b
//    b := Int
console.log("should be: [Int] -> Int");
console.log(prettyT(assign(weirdFnType, idFnType)));