dbrack

objects that implement map are functors. So, Array is a functor, and Array.filter is a higher order function

abstract

a functor is an object which acts as a container for a value, which then allows you to APPLY one or more functions to that value, and returns a new functor (in case of .map(), an Array) containing the transformed value.

See also here

swissmanu

#!/bin/sh

BOLD=$(tput BOLD)
NORMAL=$(tput sgr0)
RED='\033[0;31m'

LOCAL_SETTINGS_BASE=~/Library/Application\ Support/Code
LOCAL_SETTINGS="${LOCAL_SETTINGS_BASE}/User"
REMOTE_SETTINGS=~/Google\ Drive/App\ Sync/vscode/Settings

swissmanu

// precondition: xs is always an array

function head(xs) {
  if (xs.length === 0) return null
  return xs[0]
}

function tail(xs) {
  return xs.slice(1)
}

swissmanu

// Example Usage:
eventually(20)(() => fetch('http://i.fail.often.com/data.json'))
  .then(data => console.log(data))
  .catch(e => console.log(e));


function eventually<T>(
  giveUpAfterNumberOfRetries: number,
  nextInterval: (numberOfRetries: number) => number = linearRetryInterval
) {

rauschma

// Demo: converting a thenable to a Promise

const fulfilledThenable = {
    then(reaction) {
        reaction('hello');
    }
};
const promise = Promise.resolve(fulfilledThenable);
console.log(promise instanceof Promise); // true
promise.then(x => console.log(x)); // hello

developit

dialog {
	position: fixed;
	top: 50%;
	left: 50%;
	right: auto;
	padding: 30px;
	transform: perspective(500px) translate(-50%, -50%);
	background: linear-gradient(to bottom, #FFF, #F4F4F4) #FFF;
	border: none;
	border-radius: 3px;

rauschma

const handler = {
  get(target, propKey, receiver) {
    if (/^_[0-9]+$/.test(propKey)) {
      const result = [];
      const first = Number(receiver);
      const last = Number(propKey.slice(1));
      for (let i=first; i<=last; i++) {
        result.push(i);
      }
      return result;

swissmanu

export type Tuple2<A, B> = [A, B];
export type Tuple3<A, B, C> = [A, B, C];
export type Tuple4<A, B, C, D> = [A, B, C, D];
export type Tuple5<A, B, C, D, E> = [A, B, C, D, E];
export type Tuple6<A, B, C, D, E, F> = [A, B, C, D, E, F];
export type Tuple7<A, B, C, D, E, F, G> = [A, B, C, D, E, F, G];
export type Tuple8<A, B, C, D, E, F, G, H> = [A, B, C, D, E, F, G, H];
export type Tuple9<A, B, C, D, E, F, G, H, I> = [A, B, C, D, E, F, G, H, I];
export type Tuple10<A, B, C, D, E, F, G, H, I, J> = [A, B, C, D, E, F, G, H, I, J];

tejacques

import * as React from 'react';
import { Component } from 'react';

export default function HOCBaseRender<Props, State,  ComponentState>(
    Comp: new() => Component<Props & State, ComponentState>) {
    return class HOCBase extends Component<Props, State> {
        render() {
            return <Comp {...this.props} {...this.state}/>;
        }
    }

rauschma

This content moved here: https://exploringjs.com/impatient-js/ch_arrays.html#quickref-arrays