type Blank<N extends number, _A extends unknown[] = []> = _A["length"] extends N ? _A : Blank<N, [..._A, unknown]>
type IsNegative<N extends number> = `${N}` extends `-${number}` ? true : false
type Absolute<N extends number> = `${N}` extends `-${infer M extends number}` ? M : N
type Sub<A extends number, B extends number> = Blank<A> extends [...Blank<B>, ...infer R] ? R["length"] : never
type Index<Len extends number, I extends number> =
  IsNegative<I> extends false ? I
  : Sub<Len, Absolute<I>>

type Slice<Arr extends unknown[], Start extends number = 0, End extends number = Arr["length"]> =
  Arr extends [...Blank<Index<Arr["length"], End>>, ...infer R1]
  ? Arr extends [...Blank<Index<Arr["length"], Start>>, ...infer R2, ...R1]
  ? R2
  : []
  : []

import type { Equal, Expect } from '@type-challenges/utils'

type Arr = [1, 2, 3, 4, 5]

type cases = [
  // basic
  Expect<Equal<Slice<Arr, 0, 1>, [1]>>,
  Expect<Equal<Slice<Arr, 0, 0>, []>>,
  Expect<Equal<Slice<Arr, 2, 4>, [3, 4]>>,

  // optional args
  Expect<Equal<Slice<[]>, []>>,
  Expect<Equal<Slice<Arr>, Arr>>,
  Expect<Equal<Slice<Arr, 0>, Arr>>,
  Expect<Equal<Slice<Arr, 2>, [3, 4, 5]>>,

  // negative index
  Expect<Equal<Slice<Arr, 0, -1>, [1, 2, 3, 4]>>,
  Expect<Equal<Slice<Arr, -3, -1>, [3, 4]>>,

  // invalid
  Expect<Equal<Slice<Arr, 10>, []>>,
  Expect<Equal<Slice<Arr, 1, 0>, []>>,
  Expect<Equal<Slice<Arr, 10, 20>, []>>,
]