Shamil Fattakhov sh-ft

The Problem

Defining records in Haskell causes accessor functions for the record's fields to be defined. There is no seperate namespace for these accessor functions.

The Goal

Be able to

use records in Haskell, which share field names.
use lenses for accessing these fields

This post is also on my blog, since Gist doesn't support @ notifications.

Components are taking center stage in Ember 2.0. Here are some things you can do today to make the transition as smooth as possible:

Use Ember CLI
In general, replace views + controllers with components
Only use controllers at the top-level for receiving data from the route, and use Ember.Controller instead of Ember.ArrayController or Ember.ObjectController
Fetch data in your route, and set it as normal properties on your top-level controller. Export an Ember.Controller, otherwise a proxy will be generated. You can use Ember.RSVP.hash to simulate setting normal props on your controller.

My issues with Modules

In researching topics for RailsCasts I often read code in Rails and other gems. This is a great exercise to do. Not only will you pick up some coding tips, but it can help you better understand what makes code readable.

A common practice to organize code in gems is to divide it into modules. When this is done extensively I find it becomes very difficult to read. Before I explain further, a quick detour on instance_eval.

You can find instance_eval used in many DSLs: from routes to state machines. Here's an example from Thinking Sphinx.

class Article &lt; ActiveRecord::Base

	{-# LANGUAGE ConstraintKinds #-}
	{-# LANGUAGE DeriveGeneric #-}
	{-# LANGUAGE FlexibleContexts #-}
	{-# LANGUAGE FlexibleInstances #-}
	{-# LANGUAGE MultiParamTypeClasses #-}
	{-# LANGUAGE PartialTypeSignatures #-}
	{-# LANGUAGE TemplateHaskell #-}
	{-# LANGUAGE TypeApplications #-}
	{-# LANGUAGE TypeFamilies #-}

	package main

	import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"

	# Change YOUR_TOKEN to your prerender token and uncomment that line if you want to cache urls and view crawl stats
	# Change example.com (server_name) to your website url
	# Change /path/to/your/root to the correct value

	# Generate $prerender_ua bool value based on user agent
	# indexation bots will get this as 1,
	# prerender user agent will always get 0 (avoid loops)
	map $http_user_agent $prerender_ua {

	default 0;

	------------------------------------------------------------------------------
	-- \| Gets the current path of the DOM Window (i.e., the contents of the
	-- address bar after the host, beginning with a "/").
	-- https://developer.mozilla.org/en-US/docs/Web/API/Location
	getWindowLocationPathname :: DOMWindow -> IO String
	#ifdef ghcjs_HOST_OS
	getWindowLocationPathname w = do
	jw <- toJSRef w
	liftM fromJSString $ js_windowLocationPathname jw

	import GHCJS.DOM.EventM (event, preventDefault)
	import GHCJS.DOM.Element

	form :: MonadWidget t m => m a -> m (Event t (), a)
	form child = do
	(form, ch) <- el' "form" child
	submit <- wrapDomEvent (_el_element form) elementOnsubmit (void $ preventDefault)
	performEvent_ (return () <$ submit)
	return (submit, ch)

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

	class BaseBreadcrumbs
	private

	def c
	controller
	end

	def edit?
	%w[edit update].include?(controller.action_name)
	end