William Makley wmakley

Lessons Learned From a Year of Elm

These are some of the lessons I wish I had learned when I first picked up Elm, before I wrote a bunch of apps that are now more difficult to maintain than they need to be.

1. Not Everything Needs to be a Package.

Breaking an Elm program up into multiple files just to reduce scrolling does not tend to work out optimally. Evan gave a really cool talk on this called "The life of a file". Files should split organically around data structures, not just to stay short. The reasons we want to keep JavaScript files as short as possible do not apply to Elm.

For example, I've created apps with a file structure like this:

	# Why?
	# * May use same IAM role or account in use for other app features.
	# * Avoid sharing same SMTP credentials across multiple apps.
	#
	# Alternatives:
	# * https://github.com/aws/aws-sdk-rails (may be overkill)
	#
	# Gemfile:
	# gem 'aws-sdk-sesv2'
	#

	#!/usr/bin/env ruby

	verses = {
	1 => "Patridges in a pear tree",
	2 => "Turtle doves",
	3 => "French hens",
	4 => "Calling birds",
	5 => "Golden rings",
	6 => "Geese a layin'",
	7 => "Swans a swimmin'",

	# Start ssh-agent if not started (WSL workaround)
	# See: https://superuser.com/questions/1010542/how-to-make-git-not-prompt-for-passphrase-for-ssh-key-on-windows/1421619#1421619
	env=~/.ssh/agent.env

	agent_load_env () { test -f "$env" && . "$env" >\| /dev/null ; }

	agent_start () {
	(umask 077; ssh-agent >\| "$env")
	. "$env" >\| /dev/null ; }

	{% assign currentYear = globals.site.dateNow \| date: "yyyy" %}
	{% for i in (0..10) -%}
	{% capture yearIncrement -%}{{currentYear \| plus: i}}{% endcapture -%}
	<option value="{{yearIncrement}}">{{yearIncrement}}</option>
	{% endfor -%}

	/*
	JSCmd.elm
	==========

	port module JSCmd exposing (..)


	port focus : String -> Cmd msg

	# Assumes 'elm' is in your PATH, and there is a directory called 'src' containing
	# your Elm source code in the same directory as this file.
	ELM = elm
	OUTPUT = ../assets/javascripts/elm # For Rails asset pipeline, but could be anything
	SRCS = MyApp.elm MyOtherApp.elm
	TARGETS = $(SRCS:.elm=.js)
	ELM_STUFF = elm-stuff/exact-dependencies.json

	all: $(TARGETS)

	#!/bin/sh
	# The main issues with Ruby 1.8.7 are that it won't build with Clang,
	# and the Net::HTTPS module won't work with modern versions of OpenSSL.
	#
	# This assumes you have already set up homebrew, and run: xcode-select --install

	brew install homebrew/dupes/apple-gcc42
	brew install libyaml libffi
	brew install https://github.com/Homebrew/homebrew-versions/raw/586b7e9012a3ed1f9df6c43d0483c65549349289/openssl098.rb
	export CC=/usr/local/bin/gcc-4.2

	<script>
	// simple jQuery version. change variables to customize.
	window.parseTLSinfo = function(data) {
	var alert_classes = 'ssl-notice alert';
	var prepend_to = 'body';

	var tls_version = parseFloat(data.tls_version.split(/\s+/)[1]);
	if (isNaN(tls_version)) { throw "couldn't parse TLS version from input: " + data.tls_version; }

	if (tls_version < 1.1) {

	/* Make wymeditor-inserted images appear correctly in front-end. Tweak margins as needed. */
	.image-align-left {
	float: left;
	margin: 10px 20px 0 10px;
	}
	.image-align-right {
	float: right;
	margin: 10px 0 10px 20px;
	}