ts-prims
Version:
Typescript Primitives
69 lines (65 loc) • 2.01 kB
text/typescript
/** Copyright 2025 by Stijn de Witt, some rights reserved */
/**
* The union of all positive numbers from `0` up to,
* but not including, `N`.
*
* `N` must be small since this type uses recursion to
* generate a union type.
*
* You should use type `Lt` in place of this one, which forces
* a safe limit on type parameter `N`.
*
* ```ts
* type lt8 = Lt<8>
* // type lt8 = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
* ```
*
* @param N The (small) positive integer number literal
* @returns All positive integer numbers less than `N`
*
* @see {@link Lt} for the recommended, safe version
*/
export type _Lt <N extends number, A extends number[] = []> =
N extends A['length'] ? A[number] :
_Lt<N, [A['length'], ...A]>
/**
* The union of all positive integers **L**ess **T**han `N`.
*
* Returns the union of all positive integers from `0` up to, but not
* including, `N`. Safe version.
*
* ```ts
* type lt8 = Lt<8>
* // type lt8 = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
* ```
*
* This type is limited to only accept small numbers for its `N` parameter.
* This makes this type safe to use. Below the surface it is delegating to
* `_Lt`, the unrestricted (and therefore 'unsafe') version of this type
* that actually performs recursion to determine the range of values.
*
* @param N The positive integer literal
* @returns All positive integers less than `N`
*
* @see {@link Lte} if you need an end-inclusive range
* @see {@link _Lt} for the unsafe version
*/
export type Lt <N extends _Lt<256> | 256> = _Lt<N>
/**
* The union of all positive integers **L**ess **T**han or
* **E**qual to `N`.
*
* Returns the union of all positive integers from `0` up to and
* including, `N`.
*
* ```ts
* type Lte7 = Lte<7>
* // type Lte7 = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
* ```
*
* @param N The positive number literal
* @returns All positive numbers less than or equal to `N`
*
* @see {@link Lt} if you need an end-exclusive range
*/
export type Lte<N extends _Lt<256> | 256> = Lt<N> | N