pipe-ts

What is pipe?

Installation

1yarn add pipe-ts
2
3npm install pipe-ts

pipe

Create a new function which pipes its value through the list functions.

1const add1 = (n: number) => n + 1;
2const times2 = (n: number) => n * 2;
3
4const add1ThenTimes2 = pipe(
5    add1,
6    times2,
7);
8const result: number = add1ThenTimes2(1);
9
10assert.strictEqual(result, 4);

Allows first function to have any number of parameters (0+), thanks to TypeScript's generic rest parameters

1// First function has multiple parameters
2
3const difference = (a: number, b: number) => a - b;
4const add1 = (n: number) => n + 1;
5
6const differenceThenAdd1 = pipe(
7    difference,
8    add1,
9);
10const result: number = differenceThenAdd1(5, 4);
11
12assert.strictEqual(result, 2);

1// First function has 0 parameters
2
3const getNumber = () => 1;
4const add1 = (n: number) => n + 1;
5
6const getNumberThenAdd1 = pipe(
7    getNumber,
8    add1,
9);
10const result: number = getNumberThenAdd1();
11
12assert.strictEqual(result, 2);

pipeWith

Transform a value by piping it through the listed functions. Sugar syntax for pipe(f, g)(value).

1const add1 = (n: number) => n + 1;
2const times2 = (n: number) => n * 2;
3
4const result: number = pipeWith(1, add1, times2);
5
6assert.strictEqual(result, 4);

Note about number of functions

pipe and pipeWith currently support up to 9 functions. If need be, we are open to adding more overloads to increase this limit.

We are also open to adding an array overload, so any number of funtions can be passed.

When this matters

If a function passed to pipe or pipeWith relies on a specific context of execution (this), you cannot call it by passing the reference (point-free style).

Use an anonymous function instead.

Bad

1pipeWith('foo', localStorage.getItem);

Good

1pipeWith('foo', key => localStorage.getItem(key));

Also good

1pipeWith('foo', localStorage.getItem.bind(localStorage)),

Development

yarn
npm run start