functional/README.md

tk-functional
=============

[![pipeline status](https://gitlab.com/thunderk/tk-functional/badges/master/pipeline.svg)](https://gitlab.com/thunderk/tk-functional/commits/master)
[![coverage report](https://gitlab.com/thunderk/tk-functional/badges/master/coverage.svg)](https://gitlab.com/thunderk/tk-functional/commits/master)
[![npm version](https://img.shields.io/npm/v/tk-functional.svg)](https://npmjs.com/tk-functional)
[![npm size](https://img.shields.io/bundlephobia/min/tk-functional.svg)](https://bundlephobia.com/result?p=tk-functional)

About
-----

Provides some common helpers for functional-style programming.

Typescript definitions are included.

Issues can be reported on [GitLab](https://gitlab.com/thunderk/tk-functional/issues).

Functions
---------

**nop** does nothing (useful for some callbacks):

```typescript
new ConstructorWithMandatoryCallback(nop)
```

**identity** returns its argument untouched:

```typescript
a === identity(a)  // => true
```

**always** and **never** return true and false respectively

```typescript
always()  // => true
never()  // => false
```

**partial** applies a partial configuration object as first argument of compatible functions:

```typescript
const sum = (args: {a: number, b: number}) => args.a + args.b
const plus1 = partial({a: 1}, sum);
plus1({b: 8})  // => 9
```

**cmp** simplifies the use of array sorting:

```typescript
[8, 3, 5].sort(cmp())                            // => [3, 5, 8]
[8, 3, 5].sort(cmp({ reverse: true }))           // => [8, 5, 3]
[-2, 8, -7].sort(cmp({ key: Math.abs }))         // => [-2, -7, 8]
```