Dan Minshew newswim

`FreeAp f` is a `Comonad`

While thinking about comonads as spaces and Day convolution, I realized an interesting thing. The free applicative functor generated by a comonad f is also a comonad.

The free applicative can be defined in a few different ways, but I like to define it like this:

data FreeApplicative f a = Pure a | Free (Day f (FreeApplicative f) a)

Lightning Talk proposal for ReactiveConf 2017 http://www.reactiveconf.com #ReactiveConf

Porting Prezi to Elm in 99 lines of code

Elm is a statically-typed functional programming language. Its compiler produces safe JavaScript which is guaranteed to be free of runtime exceptions. Moreover Elm is packed with a bunch of powerful abstractions which let us build visual and reactive Web applications in a few lines of code.

As an example, I show the implementation of a simple framework for building Prezi-like presentations. It's just 99 lines of code!

A non-exhaustive list of WebGL and WebGPU frameworks and libraries. It is mostly for learning purposes as some of the libraries listed are wip/outdated/not maintained anymore.

Engines and libraries ⚙️

Name	Stars	Last Commit	Description
three.js	![GitHub

type StringBool = "true"|"false";


interface AnyNumber { prev?: any, isZero: StringBool };
interface PositiveNumber { prev: any, isZero: "false" };

type IsZero<TNumber extends AnyNumber> = TNumber["isZero"];
type Next<TNumber extends AnyNumber> = { prev: TNumber, isZero: "false" };
type Prev<TNumber extends PositiveNumber> = TNumber["prev"];

React lifecycle cheatsheet

Method	Side effects¹	State updates²	Example uses
Mounting
`componentWillMount`		✓	Constructor equivalent for `createClass`
`render`			Create and return element(s)
`componentDidMount`	✓	✓	DOM manipulations, network requests, etc.
Updating
`componentWillReceiveProps`		✓	Update `state` based on changed `props`

A composable pattern for pure state machines with effects

State machines are everywhere in interactive systems, but they're rarely defined clearly and explicitly. Given some big blob of code including implicit state machines, which transitions are possible and under what conditions? What effects take place on what transitions?

There are existing design patterns for state machines, but all the patterns I've seen complect side effects with the structure of the state machine itself. Instances of these patterns are difficult to test without mocking, and they end up with more dependencies. Worse, the classic patterns compose poorly: hierarchical state machines are typically not straightforward extensions. The functional programming world has solutions, but they don't transpose neatly enough to be broadly usable in mainstream languages.

Here I present a composable pattern for pure state machiness with effects,

	/*
	remote-data ported to ReasonML

	See also https://github.com/krisajenkins/remotedata
	Tools for fetching data from remote sources (incl. HTTP).
	*/

	type remoteData 'e 'a
	= NotAsked
	\| Loading

	import React from 'react'
	import { withRouter, Link } from 'react-router-dom'
	import { graphql, compose } from 'react-apollo'
	import { Formik } from 'formik'
	import Yup from 'yup'

	import FormWideError from '../elements/form/FormWideError'
	import TextInput from '../elements/form/TextInput'
	import Button from '../elements/form/Button'
	import { H2 } from '../elements/text/Headings'

	div.window-title, div.panel-header div.title, a.editor-status-mode,
	div.results-group, span.quick-open-entry-description>span.monaco-highlighted-label:first-child,
	.input, div.column.when span,
	.Equinusocio-vsc-material-theme-themes-Material-Theme-Palenight-json .mtk12,
	.Equinusocio-vsc-material-theme-themes-Material-Theme-Palenight-json .mtk9,
	.Equinusocio-vsc-material-theme-themes-Material-Theme-Palenight-json .mtk4,
	.Equinusocio-vsc-material-theme-themes-Material-Theme-Palenight-json .mtk3.mtki.detected-link,
	.Equinusocio-vsc-material-theme-themes-Material-Theme-Palenight-json span.mtk11.mtki,
	.Tyriar-theme-sapphire-theme-bright-json .mtk6,
	.zhuangtongfa-Material-theme-themes-OneDark-Pro-json .mtk6,