export * from "@principia/prelude/Utils";

export type Literal = string | number | boolean | null;

const typeOf = (x: unknown): string => (x === null ? "null" : typeof x);

export const _intersect = <A, B>(a: A, b: B): A & B => {
   if (a !== undefined && b !== undefined) {
      const tx = typeOf(a);
      const ty = typeOf(b);
      if (tx === "object" || ty === "object") {
         return Object.assign({}, a, b);
      }
   }
   return b as any;
};

export const memoize = <A, B>(f: (a: A) => B): ((a: A) => B) => {
   const cache = new Map();
   return (a) => {
      if (!cache.has(a)) {
         const b = f(a);
         cache.set(a, b);
         return b;
      }
      return cache.get(a);
   };
};