import { assign } from "../generics/generics.js";
import { makeGeneric } from "../generics/generics.js";
import { Double, Int } from "../primitives/types.js";
import { fnType } from "../structures/types.js";
import { pretty } from "../util.js";
import { getMul, NumInstances } from "./num.js";
import { numDictType } from "./num_type.js";

const square = numDict => x => getMul(numDict)(x)(x);

// NumDict a -> a -> a
const squareFnType = makeGeneric(a => 
  fnType
    (numDictType(a))
    (fnType(a)(a))
  );

console.log("should be: Int -> Int");
console.log(pretty(assign(squareFnType, makeGeneric(() => numDictType(Int)))));

console.log("should be: Double -> Double");
console.log(pretty(assign(squareFnType, makeGeneric(() => numDictType(Double)))));

// to call 'square' we need:
//   - the type of our argument (=Int)
//   - access to a mapping from types to their typeclass instantiation
console.log("");
console.log(square(NumInstances.get(Int))(42n)); // 1764n