mbylstra

Elm and Typescript: comparison of type checking features

Each of these examples assume the usage of --strict mode in Typescript

Enums

Elm

Can be implemented using “Custom Types” https://guide.elm-lang.org/types/custom_types.html

nepsilon

Auto-backup your configuration files with Vim

Not using versioning on your configuration files and editing them with Vim?

Use Vim’s backup option to automatically keep a copy of past versions. To put in your ~/.vimrc:

"Turn on backup option
set backup

oliviertassinari

// @flow weak

import raven from 'raven-js';
import config from 'config';

const SENTRY_DSN = 'https://[email protected]/YYYY';

function sendQueue() {
  const sentryOffline = JSON.parse(window.localStorage.sentryOffline);

yang-wei

When receiving JSON data from other resources(server API etc), we need Json.Decode to convert the JSON values into Elm values. This gist let you quickly learn how to do that.

I like to follow working example code so this is how the boilerplate will look like:

import Graphics.Element exposing (Element, show)
import Task exposing (Task, andThen)
import Json.Decode exposing (Decoder, int, string, object3, (:=))

import Http

yang-wei

Should be work with 0.18

Destructuring(or pattern matching) is a way used to extract data from a data structure(tuple, list, record) that mirros the construction. Compare to other languages, Elm support much less destructuring but let's see what it got !

Tuple

myTuple = ("A", "B", "C")
myNestedTuple = ("A", "B", "C", ("X", "Y", "Z"))

robinheghan

module Main where

import Signal


type alias Message =
    { operation : String
    , message : String
    }

mgold

-- a distilation of https://github.com/elm-lang/elm-plans/issues/7

{- Mailbox is renamed Dispatcher, although this name is the part I'm least certain about.
   The address field is replaced with a dispatch field.
   It's minor, but I've found it helpful to put dispatch second, since the signal is easier to explain.
-}
type alias Dispatcher a = 
    { signal : Signal a 
    , dispatch : a -> Message -- the big change
    }

laszlopandy

Elm Style Guide

Purpose

The goal of the style guide is foremost to promote consistency and reuse of pattern from other languages in order to improve readability and make Elm easier for beginners. This includes moving Elm away from Haskell’s indentation style and even making some parts look closer to JavaScript. These decisions are intentional.

We would like Elm to look friendly and familiar to users of any language — especially JavaScript — so they can discover Elm’s powerful features without being overwhelmed. This does not intend to weaken or discourage any features of Elm, but instead to make them more accessible.

A secondary goal of the style guide is to encourage short diffs when changes are made. This makes changes more clear, and helps when multiple people are collaborating.

Whitespace

bsweger

import django
django.VERSION