typescript-tuple

TypeScript Tuple

Generics to work with tuples in TypeScript

Requirements

• TypeScript ≥ 3.0.0

Usage

IsFinite

import { IsFinite } from 'typescript-tuple'

type Foo = IsFinite<[0, 1, 2]> // Expect: true
const foo: Foo = true

type Bar = IsFinite<[0, 1, 2, ...number[]]> // Expect: false
const bar: Bar = false

type Baz = IsFinite<[0, 1, 2], 'finite', 'infinite'> // Expect: 'finite'
const baz: Baz = 'finite'

First

import { First } from 'typescript-tuple'
type Foo = First<['a', 'b', 'c']> // Expect: 'a'
const foo: Foo = 'a'

Last

import { Last } from 'typescript-tuple'
type Foo = Last<['a', 'b', 'c']> // Expect: 'c'
const foo: Foo = 'c'

Append

import { Append } from 'typescript-tuple'
type Foo = Append<['a', 'b', 'c'], 'x'> // Expect: ['a', 'b', 'c', 'x']
const foo: Foo = ['a', 'b', 'c', 'x']

Prepend

import { Prepend } from 'typescript-tuple'
type Foo = Prepend<['a', 'b', 'c'], 'x'> // Expect: ['x', 'a', 'b', 'c']
const foo: Foo = ['x', 'a', 'b', 'c']

Reverse

import { Reverse } from 'typescript-tuple'
type Foo = Reverse<['a', 'b', 'c']> // Expect: ['c', 'b', 'a']
const foo: Foo = ['c', 'b', 'a']

Concat

import { Concat } from 'typescript-tuple'
type Foo = Concat<['a', 'b', 'c'], [0, 1, 2]> // Expect ['a', 'b', 'c', 0, 1, 2]
const foo: Foo = ['a', 'b', 'c', 0, 1, 2]

Repeat

import { Repeat } from 'typescript-tuple'

// Basic
type Foo = Repeat<'x', 5> // Expect ['x', 'x', 'x', 'x', 'x']
const foo: Foo = ['x', 'x', 'x', 'x', 'x']

// Using union
type Bar = Repeat<'x', 1 | 3 | 4> // Expect ['x'] | ['x', 'x', 'x'] | ['x', 'x', 'x', 'x']
const bar1: Bar = ['x']
const bar3: Bar = ['x', 'x', 'x']
const bar4: Bar = ['x', 'x', 'x', 'x']

// Using ambiguous 'number' type
type Baz = Repeat<'x', number> // Expect 'x'[]
const baz: Baz = Array<number>()

NOTES:

• Due to TypeScript design limitations, using floating point numbers and negative numbers might lead to infinite loop within TSC compiler, avoid doing this.

ConcatMultiple

import { ConcatMultiple } from 'typescript-tuple'
type Foo = ConcatMultiple<[[], ['a'], ['b', 'c']]> // Expect ['a', 'b', 'c']
const foo: Foo = ['a', 'b', 'c']

License

MIT @ Hoàng Văn Khải