Generate typings for selectors

generateSelector.ts

import * as fs from "fs";
import * as path from "path";

function main(p: number): string {
  function create(prefix: string, join = ", "): string {
    return Array(p)
      .fill("_")
      .map((_, i) => `${prefix}${i + 1}`)
      .join(join);
  }
  function create2(): string {
    return Array(p)
      .fill("_")
      .map((_, i) => `ParametricSelector<S${i + 1}, P${i + 1}, R${i + 1}>`)
      .join(", ");
  }
  function create3(): string {
    return Array(p)
      .fill("_")
      .map((_, i) => `res${i + 1}: R${i + 1}`)
      .join(", ");
  }

  const S = create("S");
  const P = create("P");
  const R = create("R");
  const selectors = create2();
  const combiner = create3();

  return `
  // ${p} selectors
  export function createSelector<${S}, ${P}, ${R}, T>(
    selectors: [${selectors}],
    combiner: (${combiner}) => T
  ): OutputParametricSelector<${create("S", " & ")}, ${create("P", " & ")}, T, (${combiner}) => T>;`;
}

const fileData = [
  `/* eslint-disable */
import {ParametricSelector, OutputParametricSelector} from "reselect";

declare module "reselect" {`,
];

for (let i = 14; i <= 21; i++) {
  fileData.push(main(i));
}

fileData.push("}");

fs.writeFileSync(path.resolve(__dirname, "reselect.d.ts"), fileData.join("\n"));