Normal TS calculator made with pattern mathing

normal-calculator

type Operations = 'sum' | 'sub' | 'mul' | 'div';
type RecursiveReturn = [number, (args: Array<number>, next?: Operations) => RecursiveReturn] 

const calculator =
  (operation: Operations, prev?: number) =>
    (args: Array<number>, next?: Operations): RecursiveReturn => {
      const nums = prev === undefined ? [...args] : [...args, prev];
      const partial = nums
        .reduce((prev: number, curr: number) => ({
          ['sum']: prev + curr,
          ['sub']: prev - curr,
          ['mul']: prev * curr,
          ['div']: prev / curr,
        }[operation]), 0);

      if (next) {
        return [partial, calculator(next, partial)]
      }
      return [partial, calculator(operation, partial)]
    }



const sum = calculator('sum');
const [res] = sum([1,2]);
console.log(res); // 3
const mul = calculator('mul');
const [res2, mul2] = mul([1,2], "mul");
console.log(res2); // 2
const [res3, calc2] = mul2([2]);
console.log(res3); // 4