List.ts

import * as Func from "./Function"

type BuildList<
  T,
  Length extends number,
  List extends unknown[]
> = List["length"] extends Length ? List : BuildList<T, Length, [T, ...List]>

export type From<T, Length extends number> = BuildList<T, Length, []>

export type Set<T, N extends number, List extends unknown[]> = {
  [k in keyof List]: k extends `${N}` ? T : List[k]
}

export type Tail<Tuple extends unknown[]> = ((
  ...args: Tuple
) => unknown) extends (_: unknown, ..._1: infer Rest) => unknown
  ? Rest
  : never

export type Eq<X, Y> = [X, Y] extends [Y, X] ? true : false

export type LMap<K extends Func.FNames, XS extends any[]> = XS extends [
  infer H,
  ...infer Tail
]
  ? [Func.Apply<K, H>, ...LMap<K, Tail>]
  : []

export type Filter<K extends Func.FNames, XS extends any[]> = XS extends [
  infer H,
  ...infer Tail
]
  ? Func.Apply<K, H> extends false | never
    ? [...Filter<K, Tail>]
    : [H, ...Filter<K, Tail>]
  : []