dnson imnutz

Architecture in Elm

This document is a collection of concepts and strategies to make large Elm projects modular and extensible.

We will start by thinking about the structure of signals in our program. Broadly speaking, your application state should live in one big foldp. You will probably merge a bunch of input signals into a single stream of updates. This sounds a bit crazy at first, but it is in the same ballpark as Om or Facebook's Flux. There are a couple major benefits to having a centralized home for your application state:

There is a single source of truth. Traditional approaches force you to write a decent amount of custom and error prone code to synchronize state between many different stateful components. (The state of this widget needs to be synced with the application state, which needs to be synced with some other widget, etc.) By placing all of your state in one location, you eliminate an entire class of bugs in which two components get into inconsistent states. We also think yo

	import Html exposing (Html, Attribute)
	import Html.Attributes
	import Html.Events
	import Signal exposing (Address)
	import List
	import String
	import StartApp

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	--- HELPER CODE --

	--------------------------
	-- CORE LIBRARY IMPORTS --
	--------------------------
	import Task exposing (Task, ThreadID, andThen, sequence, succeed, spawn)
	import Json.Decode exposing (Decoder, list, int, string, (:=), map, object2)
	import Signal exposing (Signal, Mailbox, mailbox, send)
	import List

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	-- THIRD PARTY LIBRARY IMPORTS --