@teleology/fp

A collection of functional utilities supporting pipes

pipe

Accepts a variadic list of functions and passes one argument to the next from top-to-bottom.

Example:

const { pipe } = require('@teleology/fp');

const a = (s) => s - 12;
const b = (s) => s * 3;

pipe(
    a, 
    b, 
    console.log
)(10); // -6

compose

Accepts a variadic list of functions and passes one argument to the next from bottom-to-top.

Example:

const { compose } = require('@teleology/fp');

const a = (s) => s - 12;
const b = (s) => s * 3;

compose(
    console.log,
    a, 
    b
)(10); // 18

parallel

Accepts a variadic list of functions and returns a curried function. The curried function can then be invoked and will delegate its arguments in parallel across the functions.

Example:

const { parallel } = require('@teleology/fp');
const logDb = require('./apis/logs');

// Writes to both local logs as well as to our external api
const logger = parallel(
    logDb,
    console.log
);

logger({
    source: 'app',
    action: 'clicked login',
    time: Date.now(),
});

toss

Curries an error message returning an invocable function to throw. The invocable function can accept params to assign additional data to the Error.

Example:

const { toss } = require('@teleology/fp');

toss('An error occured')({ code: 403, reason: 'Entity already exists' });
// Error: An error occured
//     ...
//     at internal/main/run_main_module.js:17:47 {
//   code: 403, 
//   reason: 'Entity already exists'
// }

set

Sets a value at a dot notation path within an object or array, can be curried.

Example:

const { set } = require('@teleology/fp');

set('a.b.c[1].z', 'hello')({})  // {"a":{"b":{"c":[null,{"z":"hello"}]}}}
set('[0].z', 'hello', [])       // [ { z: 'hello' } ]

get

Curry a dot notation path and default value, returns an invocable function requiring a target object.

Example:

const { get } = require('@teleology/fp');

get('[0].a.b')([
  {
    a: {
      b: 'hello',
    },
  },
]); // hello

pick

Curry an array of dot notation paths, with optional settings. Returns an invocable function requiring a target object.

Example:

const { pick } = require('@teleology/fp');

pick(['a.b', 'a.c[0]', 'a.c[2]'])({
  a: {
    b: 'hi',
    c: [1, 2, 3],
  },
}); // { a: { b: 'hi', c: [ 1, <1 empty item>, 3 ] } }


// Clear out missing values
pick(['a.b', 'a.c[0]', 'a.c[2]'], { clean: true })({
  a: {
    b: 'hi',
    c: [1, 2, 3],
  },
}); // { a: { b: 'hi', c: [ 1, 3 ] } }

curry

Curry a specific function with a known arity. Please note, optional arguments are not considered during invocation unless they are explicity set.

Example:

const { curry } = require('@teleology/fp');

const test = (a, b, c) => console.log([a, b, c]);

const curried = curry(3, test);

// allows for flexibility
curried(1, 2, 3); // [1, 2, 3]
curried(1)(2)(3); // [1, 2, 3]
curried(1)(2, 3); // [1, 2, 3]
curried(1, 2)(3); // [1, 2, 3]

map

A curried map function to be invoked within an Array.

Example:

const { map } = require('@teleology/fp');

map((a) => a.id)([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // [ '1', '2' ]

map(['id'])([
  {
    id: '1',
    name: 'bob',
  },
  {
    id: '2',
    name: 'chris',
  },
]) // [ { id: '1' }, { id: '2' } ]

filter

A curried filter function to be invoked within an Array.

Example:

const { filter } = require('@teleology/fp');

filter((a) => a.id === '1')([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // [ { id: '1' } ]

filter({ id: '1' })([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // [ { id: '1' } ]

find

A curried find function to be invoked within an Array.

Example:

const { find } = require('@teleology/fp');

find((a) => a.id === '1')([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // { id: '1' }

find({ id: '1' })([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // { id: '1' }

some

A curried some function to be invoked within an Array.

Example:

const { some } = require('@teleology/fp');

some((a) => a.id === '1')([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // true

some({ id: '1' })([
  {
    id: '1',
  },
  {
    id: '2',
  },
]); // true

clean

Recursively removes empty values. An empty value is: null, empty string, undefined, an empty array or object.

Example:

const { clean } = require('@teleology/fp');

clean({
  a: null,
  b: '',
  c: undefined,
  d: {},
  e: [],
  f: 'hello',

  nested: { will: { be: { removed: {} } } },
}); // { f: 'hello' }

nonce

Wraps a function and prevents it from being called more than n times. Optional second params is the number of times, default is once.

Example:

const { nonce } = require('@teleology/fp');

const log = nonce(console.log);

log('hi'); // hi
log('bonjour');

retry

Given a function that may throw, retry up to n times.

Example:

const { retry } = require('@teleology/fp');

const greet = retry(async (name) => {
  throw new Error(`${name}, failed to be greeted`);
}, 3);

greet('bob').catch(console.log); // e Error: bob, failed to be greeted

settle

Mimics the traditional Promise.all but wraps each promise to avoid a throw. Errors contain a reason, successes a value. If a single promise is passed in, the result is a curried promise whose result is wrapped.

const { settle } = require('@teleology/fp');

const ps = [0, 1, 2, 3, 4].map((a) => (async () => a)());

settle(ps).then(console.log);
// [
//   { success: true, value: 0 },
//   { success: true, value: 1 },
//   { success: true, value: 2 },
//   { success: true, value: 3 },
//   { success: true, value: 4 },
// ]

const safe = settle(async (num) => {
  throw new Error(`Failed, ${num}`);
});

safe(10).then(console.log);
// {
//   success: false,
//   reason: Error: Failed, 10
//   ...
// }

timeout

Curries a given function, millis and ensures an error is thrown when a timeout occurs.

const { timeout } = require('@teleology/fp');

const timed = timeout(
  async () => new Promise((resolve) => setTimeout(resolve, 9000)), // long running task
  200, // timeout
);

timed('hello').then(console.log).catch(console.log);

poll

A wrapper around a functon to long-poll at pre-defined intervals. Can be used with defaults or a custom rolloff function.

const { poll } = require('@teleology/fp');

const fn = async () => console.log('hello');

const cancel = poll(fn); // calls fn every 200ms

const cancel2 = poll(fn, 1000); // calls fn every 1000ms

const linear = async (i) => new Promise((res) => setTimeout(res, i * 1000));

const cancel3 = poll(fn, linear); // rolls off in a lineaer fashion

noop

A function that does nothing.

const { noop } = require('@teleology/fp');

// I do nothing
noop();

Changelog

2.0.2

• Added curry function

2.0.0

• Changed how pick operates, to migrate use get which is now exposed
• Updated clean to remove empty array items

1.0.14

• Added noop function

1.0.10

• Adding timeout function

1.0.9

• Adding retry, settle functions
• Bug fixes for pipe + compose

1.0.6

• Adding once function

1.0.4

• Adding a clean function to remove empty values

1.0.1

• Renaming broadcast to parallel
• Added find, filter functions
• Updated README with examples
• Updated toss to be invoked later to capture param