CoffeeScript

Still worth a look

Me?

• Matt McKellar-Spence

• GitHub: MattMS

• Twitter: MattMS

Such magic?

• reveal.js

• Jade

• Stylus

...and a little CoffeeScript :)

First

• ES(6|7|201[56]) look (mostly) good.

• I like CoffeeScript syntax, you may not.

• Same idea as Sass, Less, Jade, etc.

Hard and fast

But totally worth learning.

• Vim

• Regular expressions

And now for something completely different...

Python!

python.org

First step to liking CoffeeScript.

Pretty basic

hopefully_a_name = input('Who be ye? ')

print('Yo', hopefully_a_name)

Fully functional

def but_is_it_awesome(questionable_item):
	if questionable_item in ['CoffeeScript', 'Python']:
		return 'yeah'

	elif questionable_item != 'Java':
		return 'maybe'

	else:
		return 'nah'

print(but_is_it_awesome('Lua'))

Stay classy

class MeatSack:

	def __init__(self, name):
		self.name = name

	def talk(self):
		return 'Me {}'.format(self.name)

meaty = MeatSack('T-Bag')

print(meaty.talk())

Reusing concepts

10 in [2, 6, 12, 16, 60]

'nah' in 'banana'

'base' in {'base': 0xc, 'value': 'a'}

Why Python?

• Syntax is well-considered.

• You were going to indent it anyway, right?

What about YAML!

yaml.org

(nearly coffee-time)

Orderly but approachable

- date: 2015-09-30
  place: Typewriter Factory
  task: Talk about CoffeeScript.

- date: 2015-10-01
  place: Antarctic Division
  task: Last day shenanigans.

- date: 2015-10-02
  place: The Winston
  task: Eat ribs and drink beer.

Why YAML?

• Safe for our puny human brains.

• Only write what you need.

...but

• Better for configuration than transport.

• Use safe_load.

CoffeeScript!

Yay?

Must know JavaScript

• CoffeeScript is JavaScript.

• Most documentation/libraries are in JavaScript.

• You will probably debug the JavaScript with browser tools.

A simple function

greet = (name)->
	'Hello ' + name

Free returns!

Do you really like brackets?

console.log(greet('World'))

or

console.log greet 'World'

(Sorry Lisp folk)

Think of the command line.

git add main.coffee

Well, think in reverse (if you must).

'World' > greet > console.log

Yes, long lines are confusing

wha = do_something with_this + this_too and_me / wait_what

which is apparently

wha = do_something(with_this + this_too(and_me / wait_what))

So instead...

Moar lines!

chance_of_distracting_shopkeep = attractiveness * magic_skillz

shopkeep_attention = 1 / shopkeep_hours_on_shift

pizza_slices_acquired =
	if chance_of_distracting_shopkeep > shopkeep_attention
		all_the_slices
	else
		money_in_pocket / cost_of_pizza_slice

Keep it simple

• Everything is an expression (returns something).

• One liners are fun to write, but to read?

Functions and arguments

path = require 'path'

parts = path.parse path.join site, folder, file

gives

var path = require('path')

var parts = path.parse(path.join(site, folder, file))

Alternatively

path = require 'path'

parts = path.parse path.join [
	site
	folder
	file
]...

Literate CoffeeScript

I love this stuff.

Have you ever

• Separated your code with fancy comment lines?

• Run out of space with indented comments?

• Made up your own comment styles?

Describe, then code

# My cool server

	http = require 'http'

	server = http.createServer (req, res)->
		res.writeHead 200, 'Content-Type': 'application/json'
		res.end JSON.stringify ok: true

## Start server

Start the server on [port 1337](http://localhost:1337).

	server.listen 1337

It's just Markdown

• Break up sections with headings.

• All comments get the same width.

• Looks cool on GitHub.

• Readme Driven Development

The big stuff

Big comments

###
So much space to fill with (almost) whatever you like.

Literate CoffeeScript is nicer though.

You only get 2 Markdown heading levels with this.
###

Big strings

reaction = 'Woah!'

all_the_stuff = """
#{reaction}

I <em>strongly</em> dislike
<abbr title="Hypertext Markup Language">HTML</abbr>,
but how awesome is this!
"""

Big regexes

OPERATOR = /// ^ (
?: [-=]>            # function
| [-+*/%<>&|^!?=]=  # compound assign / compare
| >>>=?             # zero-fill right shift
| ([-+:])\1         # doubles
| ([&|<>])\2=?      # logic / shift
| \?\.              # soak access
| \.{2,3}           # range or splat
///

or

OPERATOR = /^(?:[-=]>|[-+*\/%<>&|^!?=]=|>>>=?|([-+:])\1|([&|<>])\2=?|\?\.|\.{2,3})/

Fancy functions

jQuery

$ ->
	console.log 'And so it begins.'

gives

$(function () {
	console.log('And so it begins.')
})

Chaining functions

$ '#much_win_button'

.on 'click', ->
	evil_corp_bank.receive user_bank.transfer_all()

.text 'You won a goat!'

Chaining arguments

id = setTimeout ->
	console.log 'Done!'

, 6000

Functions expecting objects

$ '#lil_boxy_thing'

.css
	height: '72px'
	width: '72px'

Stay safe

Equality

Always === and !==

on == true
yes is on

off != true
no inst on

Existence

if person?
	person.say_hi()

gives

if (typeof person !== "undefined" && person !== null) {
	person.say_hi()
}

CSON anyone?

[
	title: 'Fight Club'
	year: 1999
,
	title: 'The Fifth Element'
	year: 1997
,
	title: 'The Matrix'
	year: 1999
]

Remember YAML.

Inspired ES/JS

• Classes with inheritance

• Default values for functions

• Destructuring items

• Generator functions (yield)

• List comprehensions/iterators

LiveScript

livescript.net

• "Indirect descendant of CoffeeScript"

• Too many symbols for me, but no hating!

Why I still use CoffeeScript

• Markdown for comments.

• Reduces noisy characters.

• Encourages me to write simpler code.

• Fits my Jade/Stylus/Python style.

Want more?

coffeescript.org is totally worth looking over.

Thanks!

@MattMS