LiveScript - eine funktionale Alternative
Dipl.-Inf. (FH) Marco Emrich
Oct 2014 @ XP-Days
Douglas Crockford
„I don't think of myself as a guru ...“Source: http://www.yuiblog.com
The Good Parts
The Good Parts
Source: http://www.michaelthelin.se
Brendon Eich
Brendon Eich - Inventor of JavaScript
JS in 10 days
„...he had 10 days to create and produce a [...] programming language ...“www.computer.org/csdl/mags/co/2012/02/mco2012020007.pdf
♥
JS
Can we improve?
Jeremy Ashkenas
„YES!“
HTCYOFPL
CoffeScript
CoffeScript
- „a beautiful language that compiles to JS“
- „More readability, less LOC, less pain“
- „It's just JavaScript“ - coffeescript.org
- Prevents beginners from JS-landmines
CoffeScript Critism
- „CoffeeScript doesn’t go far enough“
- „not enough reason to switch“
- Targets ES3.0/IE6 ... seriously?
- Bad scoping rules
- Has landmines on it's own
- and more ....
♥
CS
Can we improve?
LifeScript
LifeScript
- Builds upon CoffeeScript (Fork)
- It's not just JavaScript
- Targets ES5/ES6 (--harmony)
- Functional Programming! Yeah!
Activly Maintained
_04.jpg)
Oct. 4: LiveScript 1.3
Github
Screenshot from Oct. 10
Production ready?
Production Ready
Tool Support: IDE
- VIM
- Emacs (3 different plugins)
- Webstorm/IntelliJ/RubyMine
- Brackets
- Visual Studio
- Kommodo
- Kate
- BBEdit
- Gedit
Tool Support
- livescript-middleware - Connect middleware for LiveScript
- livescript-browserify - Adds LiveScript support to browserify 1
- component-livescript - Adds LiveScript support to component(1)
- liveify - LiveScript transformer for browserify 2.0
- LiveScript-brunch - Adds LiveScript support to brunch
- Mimosa-LiveScript - Adds LiveScript support to Mimosa
- readymade
- ss-LiveScript - LiveScript (JS) wrapper for SocketStream 0.3
- Slake Build Utilities - Build utilities for Slakefiles
- jspackage - build tool to provide import syntax for client-side code
- require-ls - Adds LiveScript support to RequireJS
- livescript-rails - LiveScript asset pipeline for Rails > 3.1
- ruby-livescript - Ruby LiveScript is a bridge to the official LiveScript compiler
- livescript-source - LiveScript compiler for Ruby
- chem - 2D canvas-based game engine and toolchain optimized for rapid development. Supports LiveScript out of the box.
- gulp-livescript - LiveScript plugin for gulp
-
gulp - You can write gulpfile.ls in LiveScript and use
gulp --require LiveScript - make-livescript - LiveScript includes for GNU Make
- livescript-livereload - LiveScript compiler plugin for LiveReload
- plunker - You can add script.ls to a plunk, it'll be available as script.js
- skewer-livescript-mode - LiveScript eval support for EMACS Skewer
♥
LS
♥♥
LS
Hello World
LiveScript
console.log \HelloWorld
Get rid of these $@)#{!
LiveScript
if 2 + 2 == 4
console.log \Heyho
Everything is a value
LiveScript
x = if 2 + 2 == 4
then 10
else 0 that
LiveScript
hours-per-day = 8
if hours-per-day?
that * 5
Functions
LiveScript
add = (x, y) -> x + y
console.log add 2, 3
console.log add 2 3
console.log 3 `add` 4
Readable jQuery
LiveScript
$ \div .find \a .html!
Functions: Default Values
LiveScript
add = (x = 4, y = 3) -> x + y
add 2
Argumentless
LiveScript
sayHello = -> \Hallo
#alert(sayHello)
sayHello()
sayHello!
sayHello().length
sayHello!length
#[1 2 3].reverse!slice 1
Literals
LiveScript
l 64_000km
l 2~1000
l 6~12
l 16~ff
l on, off
l yes, no
String interpolation
LiveScript
l "The answer is #{2 + 2}"
variable = "world"
l "Hello #variable"
Multiline-Strings
LiveScript
l 'string can be multiline
and go on and on
beginning whitespace is
ignored'
Multiline-Strings: Heredoc
LiveScript
l '''
string can be multiline
with newlines
and go on and on
beginning whitespace is
ignored
'''
Objects
LiveScript
person =
age: 23
eye-color: 'green'
height: 180cm
oneline = color: 'blue', heat: 4
Objects: Shorthands
LiveScript
x = 1
y = 2
obj = {x: x, y: y}
obj = {x, y}
{+debug, -live}
Lists
LiveScript
[1 2 3 true \word 'hello world']
Lists
LiveScript
my-list =
32 + 1
$ \body .width!
'beautiful'
Lists
LiveScript
tree =
* 1
* 2
3
4
* 5
6
* 7
8
9
Lists
LiveScript
<[list of words]>
Ranges
LiveScript
l [1 to 5]
l [1 to 11 by 2]
l [4 to 1]
l [to 5]
l [\A to \D]
Ranges
LiveScript
list = [\a to \d]
l list[1, 3]
l list[1 to 3]
l list[*-2]
Ranges
LiveScript
l [1 til 3]
list = [\a to \d]
list[1 til 3] = [7 8]
l list
Operators: ==, is
LiveScript
2 + 4 == 6
/^e(.*)/ == 'enter'
Operators: ==, is
LiveScript
\boom is 'boom'
2 + 2 is not 4
0 + 1 isnt 1
Exercise: Functions
LiveScript
# hello should startWith h
'hello' `startsWith` 'h'
Operators: <, <?
LiveScript
l 1 < 2 < 4
l 4 <? 8
Operators: in, of
LiveScript
l 2 in [1 2 3 4 5]
l \id of id: 23, name: \rogers
Operators: for Lists
LiveScript
d <[ one two three ]> * \-
d <[a b]> ++ <[c d]>
Operators: for Strings
LiveScript
d "Hello World" * 3
d 'say yeah' - /e/
d 'say-yeah-ho' / \-
Operators: typeof
LiveScript
l typeof /^/
#l typeof! /^/
Loops
LiveScript
for x in [1 to 5]
l x
Loops
LiveScript
result = for i in [1 to 5]
i * 2
Loops
LiveScript
result = for i in [1 to 5] | i % 2 == 0
i * 2
Loops
LiveScript
result = for let x, i in [\a to \f]
"#i: #x"
Loops
LiveScript
result = for k, v of {a: 1, b: 2}
"#k#v"
Comprehensions
LiveScript
d [x * 2 for x to 10]
Comprehensions
LiveScript
object = a: 1, b: 2, c: 3
d ["#k: #v" for k, v of object]
Comprehension: Shorthand ..
LiveScript
d [.. + 1 for [1 2 3]]
Comprehension: Shorthand ..
LiveScript
list-of-obj =
* name: 'Alice'
age: 23
* name: 'Betty'
age: 26
d [..name for list-of-obj]
Switch
LiveScript
f = (p) ->
| p.length < 3 => "too small"
| p.length < 7 => p.length
| otherwise => p.slice 3
f "Hello World"
Factorial (FP Style - Yeah)
LiveScript
fact = ->
| it == 0 => 1
| otherwise => it * fact(it - 1)
#l fact 170
Exercise: Primes
Example Implementation in JS
isPrime = function(n) {
var div;
return (function(){
var i, to, results = [];
for (i = 2, to = n / 2; i <= to; ++i) {
results.push(i);
}
return results$;
}()).every(function(){
return n % div !== 0;
});
}; Exercise: Primes
LiveScript
isPrime = (n) -> false
[i for i from 1 to 20 | isPrime i] * ' ' == "1 2 3 5 7 9 11 13 15 17 19"
OOP
similar to ...
but better!
OOP
LiveScript
class A
(@x) ->
property: 1
method: (y) ->
@x + @property + y
a = new A 3
a.x #=> 3
a.property #=> 1
a.method 6 #=> 10
more OOP
...autobinding with ~>
constructor and statics with @@
inheritance with extends
mixins with implements
super ... and super!
Object.defineProperty with ~
clone and cloneport with ^^, <<<< and with
more OOP
and even more ...
Functional Programming
Currying
LiveScript
times = (x, y) --> x * y
times 2, 3
#double = (x) -> times 2, x
#double = times 2
#double 5
Destructoring
LiveScript
[first, second] = [1, 2]
l first
l second
Destructoring - Rest
LiveScript
[head, ...tail] = [1 to 5]
l head
l tail
Destructoring - Middle
LiveScript
[first, ...middle, last] = [1 to 5]
l first
l middle
l last
Destructoring - Objects
LiveScript
{name, age} =
weight: 110
name: 'emma'
age: 20
Argument Destructoring
LiveScript
set-cords = ({x, y}) -> "#x,#y"
set-cords y: 2, x: 3
Argument Destructoring with Defaults
LiveScript
set-cords =
({x = 1, y = 3} = {}) -> "#x,#y"
set-cords y: 5
#set-cords!
Access Operator
LiveScript
'Hallo'.length
(.length)('Hallo')
Operators: require
LiveScript
require! 'prelude-ls'
require! <[ fs path ]>
require! {
fs
path
lib: foo
}
Prelude: Map
LiveScript
{map} = require 'prelude-ls'
data = [{name: 'alice', age: 19},
{name: 'tessa', age: 17}]
map (.name), data
Prelude: Map
LiveScript
{map} = require 'prelude-ls'
map (.toUpperCase!), ['hi', 'there']
#map (.join '-'), [[1, 2, 3], [4, 5]]
Currying + Map
LiveScript
{map} = require 'prelude-ls'
map (* 2), [1 2 3]
Prelude: Filter
LiveScript
{filter, even} = require 'prelude-ls'
filter even, [1 to 6]
Prelude: Filter
LiveScript
{filter} = require 'prelude-ls'
data = [{name: 'alice', age: 19},
{name: 'tessa', age: 17}]
filter (.age > 18), data
Sum and Fold
LiveScript
{map, sum, fold1} = require 'prelude-ls'
sum [1 2 3]
#fold1 (+), [1 2 3]
Minimum
LiveScript
{minimum, fold1} = require 'prelude-ls'
minimum [14 35 -7 46 98]
#fold1 (<?), [14 35 -7 46 98]
Partition
LiveScript
{partition} = require 'prelude-ls'
scores = [49 58 76 43 88 77 90]
[passed, failed] = partition (> 60), scores
d passed
Composition mit << und >>
LiveScript
even = -> it % 2 == 0
invert = -> not it
odd = invert << even
#odd = even >> invert
odd 4
Streaming with |>
LiveScript
{filter, even, sum, map} = require 'prelude-ls'
sum(map((* 2), filter(even, [1 to 5])))
[1 to 5] |> filter even |>
map (* 2) |> sum
Constants
LiveScript
const x = 10
#if false then x = 3
Compile Flag
--const
Callback Flattening
LiveScript
<- setTimeout _, 500
<- setTimeout _, 500
l (new Date).getSeconds()
https://www.flickr.com/photos/alebaffa/8939535066
https://www.flickr.com/photos/tcanales/344050956
https://www.flickr.com/photos/funnyclippics/2404373039/in/photostream/
https://www.flickr.com/photos/badjonni/6978256416
https://www.flickr.com/photos/greyloch/2754795048/in/photostream/
Fizzbuzz anyone?
1 ... 100
/ 3: Fizz
/ 5: Buzz
/ 7: Bazz
1,2,Fizz,4,Buzz,
Fizz,Bazz,8,Fizz,Buzz,
11,Fizz,13,Bazz,FizzBuzz,16
FizzBuzz (Readable - somewhat)
LiveScript
[1 to 100].map (number) ->
[k for k, v of {
Fizz: 3, Buzz: 5, Bazz: 7
} when number % v == 0] * '' or
number
https://www.flickr.com/photos/jdhancock/4036482004/in/photostream/
FizzBuzz (Golf Version)
LiveScript
[1 to 100]map ->
[k+\zz for k,v of {
Fi:3,Bu:5,Ba:7
}|it%v<1]*''||it
64 characters
Exercise: String Calculator
LiveScript
calc = -> null
d calc("") == 0
d calc("3") == 3
d calc("1,2,3") == 6
d calc("1,1000,2,3") == 6
d calc("//*1*1000*2*3") == 6
d calc("//:2:2:9999:2345:5") == 9
Exercise: String Calculator (Golf-Version)
LiveScript
0 characters
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