import { Bool } from "./primitives/symbols.js";
import { typedFnType } from "./structures/function.js";
import { deepEqual } from "./util.js";

// TODO: 'Type' (and its instances) are itself instances of (String,[Type]) (=the product type of String and list of Type)
//   so is 'Type' just an alias for (String, [Type])
export const Type = { symbol: Symbol('Type'), params: [] };

export const getSymbol = type => type.symbol;
export const getParams = type => type.params;

// we can test whether types are equal:
export const eqType = deepEqual;

// a module is just a set of typed objects
// each 'typed object' is implicitly an instance of TypeLink (defined below)
export const ModuleMetaCircular = {l:[  
  // TODO? maybe follow Lean so
  //    Type.{0} : Type.{1}
  //    Type.{1} : Type.{2}
  //    ...
  // see: https://lean-lang.org/functional_programming_in_lean/functor-applicative-monad/universes.html

  // Type : Type
  {i: Type, t: Type},

  // ...typedFnType(getSymbol, fnType => fnType({in: Type, out: Int})),

  // ...typedFnType(getParams, fnType => fnType({in: Type, out: lsType(Type)})),

  ...typedFnType(eqType, fnType => fnType({
    in: Type,
    out: fnType({
      in: Type,
      out: Bool,
    })})),
]};