sebinsua/typesafe-zip-2.ts

// We check whether `T` is a numeric literal by checking that `number`
// does not extend from `T` but that `T` does extend from `number`.
type IsNumericLiteral<T> = number extends T
  ? false
  : T extends number
  ? true
  : false;
type InvalidArgument<T> = readonly [never, T];
 
type Zipped<A extends readonly (readonly any[])[]> = {
  [RowIndex in keyof A[0]]: RowIndex extends "length" ? number : {
    [ArrayIndex in keyof A]: A[ArrayIndex] extends readonly any[] ? A[ArrayIndex][RowIndex] : never;
  };
};

type NumericRange<TotalLength extends number, TempRange extends any[] = []> =
  TempRange['length'] extends TotalLength ? TempRange : NumericRange<TotalLength, [...TempRange, TempRange['length']]>;

type TupleFromKeys<T, K extends readonly (keyof T)[]> = {
  [I in keyof K]: K[I] extends keyof T ? T[K[I]] : never;
};

type FixedSequence<T extends readonly (readonly any[])[]> = TupleFromKeys<Zipped<T>, NumericRange<T[0]['length']>>;

function zip<const T extends readonly (readonly any[])[]>(...arrays:
  true extends IsNumericLiteral<T['length']>
    ? T
    : InvalidArgument<T>
): FixedSequence<T> {
  const minLength = Math.min(...arrays.map(arr => arr.length));
  const result: any[][] = [];

  for (let i = 0; i < minLength; i++) {
    const zippedItem = arrays.map(arr => arr[i]);
    result.push(zippedItem);
  }

  return result as FixedSequence<T>;
}

const grid = [
  ['a', 1, true],
  ['b', 2, false],
  ['c', 3, true]
] as const;

const [col1, col2, col3] = zip(...grid);

console.log(col1);
console.log(col2);
console.log(col3);

// We check whether `T` is a numeric literal by checking that `number`
// does not extend from `T` but that `T` does extend from `number`.
type IsNumericLiteral<T> = number extends T
  ? false
  : T extends number
  ? true
  : false;
type UserProvidedInvalidArgument<T> = readonly [invalidArgumentToZip: never];
 
type Zipped<A extends readonly (readonly any[])[]> = {
  [RowIndex in keyof A[0]]: RowIndex extends "length" ? number : {
    [ArrayIndex in keyof A]: A[ArrayIndex] extends readonly any[] ? A[ArrayIndex][RowIndex] : never;
  };
};

type NumericRange<TotalLength extends number, TempRange extends any[] = []> =
  TempRange['length'] extends TotalLength ? TempRange : NumericRange<TotalLength, [...TempRange, TempRange['length']]>;

type TupleFromKeys<T, K extends readonly (keyof T)[]> = {
  [I in keyof K]: K[I] extends keyof T ? T[K[I]] : never;
};

type FixedSequence<T extends readonly (readonly any[])[]> = TupleFromKeys<Zipped<T>, NumericRange<T[0]['length']>>;

function zip<U extends (readonly any[]), T extends U[]>(...arrays: T):
  true extends IsNumericLiteral<T[number]['length']>
    ? FixedSequence<T>
    : UserProvidedInvalidArgument<T> {
  const minLength = Math.min(...arrays.map(arr => arr.length));
  const result: any[][] = [];

  for (let i = 0; i < minLength; i++) {
    const zippedItem = arrays.map(arr => arr[i]);
    result.push(zippedItem);
  }

  return result as any;
}

const grid1 = [
  ['a', 1, true] as const,
  ['b', 2, false] as const,
  ['c', 3, true] as const,
];
const grid2 = [
  ['a', 1, true],
  ['b', 2, false],
  ['c', 3, true]
] as const;
const grid3 = [
  ['a', 1, true],
  ['b', 2, false],
  ['c', 3, true]
];

const [col1, col2, col3] = zip(...grid1);
const [col4, col5, col6] = zip(...grid2);
const [col7, col8, col9] = zip(...grid3);

console.log(col1);
console.log(col2);
console.log(col3);

// We check whether `T` is a numeric literal by checking that `number`
// does not extend from `T` but that `T` does extend from `number`.
type IsNumericLiteral<T> = number extends T
  ? false
  : T extends number
  ? true
  : false;
type UserProvidedInvalidArgument<T> = readonly [invalidArgumentToZip: never];
 
type Zipped<A extends readonly (readonly any[])[]> = {
  [RowIndex in keyof A[0]]: RowIndex extends "length" ? number : {
    [ArrayIndex in keyof A]: A[ArrayIndex] extends readonly any[] ? A[ArrayIndex][RowIndex] : never;
  };
};

type NumericRange<TotalLength extends number, TempRange extends any[] = []> =
  TempRange['length'] extends TotalLength ? TempRange : NumericRange<TotalLength, [...TempRange, TempRange['length']]>;

type TupleFromKeys<T, K extends readonly (keyof T)[]> = {
  [I in keyof K]: K[I] extends keyof T ? T[K[I]] : never;
};

type FixedSequence<T extends readonly (readonly any[])[]> = TupleFromKeys<Zipped<T>, NumericRange<T[0]['length']>>;

function zip<const U extends (readonly any[]), T extends U[]>(...arrays: T):
  true extends IsNumericLiteral<T[number]['length']>
    ? FixedSequence<T>
    : UserProvidedInvalidArgument<T> {
  const minLength = Math.min(...arrays.map(arr => arr.length));
  const result: any[][] = [];

  for (let i = 0; i < minLength; i++) {
    const zippedItem = arrays.map(arr => arr[i]);
    result.push(zippedItem);
  }

  return result as any;
}

// type GetLength<A extends any[]> = A['length'];
// type Increment<N extends number, A extends any[] = []> = GetLength<A> extends N ? GetLength<[...A, any]> : Increment<N, [...A, any]>

type PrependNumber<A extends any[]> = [...A, A['length']];
type CreateTuple<N extends number, A extends any[] = []> = A['length'] extends N ? A : CreateTuple<N, PrependNumber<A>>;
type Drop<N extends number, A extends any[], B extends any[] = []> = B['length'] extends N ? A : Drop<N, A extends [any, ...infer R] ? R : never, PrependNumber<B>>;

type NRange<Start extends number, Stop extends number> = Drop<Start, CreateTuple<Stop>>;

function range<Start extends number, Stop extends number>(start: Start, stop: Stop): NRange<Start, Stop> {
  const result: number[] = [];
  for (let i = start; i < stop; i++) {
    result.push(i);
  }
  return result as NRange<Start, Stop>
}

function enumerate<Items extends ReadonlyArray<any>, Length extends Items['length'](items: Items) {
  return zip(range(0, items.length as Length), items);
}

const output = enumerate(["a", "b", "c", "d", "e"] as const);