Python to LiveScript@hychen

for PyCon APAC 2014

Star to learn LiveScript after join a g0v.tw, a open civic hacking community.

劣即 是夯

JavaScript everywhere

LiveScript• concise syntax.

• say bye to bad parts of JavaScript.

• many improvements for OOP.

• many features of FP.

• http://livescript.net/

• go there and try compiling

JS

LS

use -> to replace anonymous function

LS

LS

use bound call to remove `that = this`

LS

LS

@ = this

LS

LS

func! === func()

LS

LS

‘foo’ === \foo

LS

LS

use back call

LS

LS

use bound back call

JS

LS

Package Manager

you can use any JavaScript modules in LiveScript.

NPM

PyPi

ImportImport os !require! os

PY

LS

PY

LS

from os import path !path = require os .path

REPL

user@host: python Python 2.7.6 (default, Nov 17 2013, 16:03:54) [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>>

user@host: lsc LiveScript 1.2.0 - use 'lsc --help' for more information ls>

Python

LiveScript

Inspect attributes of an object

Object.keys

dir>>> dir(path) ['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_joinrealpath', '_unicode', '_varprog', 'abspath', 'altsep', 'basename', 'commonprefix', 'curdir', 'defpath', 'devnull', 'dirname', 'exists', 'expanduser', 'expandvars', 'extsep', 'genericpath', 'getatime', 'getctime', 'getmtime', 'getsize', 'isabs', 'isdir', 'isfile', 'islink', ‘ismount', ….

ls> Object.keys path [ 'resolve', 'normalize', 'join','relative','sep','delimiter', 'dirname', 'basename','extname','exists', 'existsSync', '_makeLong' ]

Help

PY

LS X

pydoc

Object Model

Please check the slide “Python New-Style Object v.s. JavaScript prototype, COSCUP 2012”

The basic object model of LiveScript should be the same as JavaScript.

List construction[1, 2, [3, 4], [5,6]]PY & LS

1 spaceLS

List Property Access

[1, 2, [3,4]][0]PY & LS

LS

LS

[1, 2, [3,4]].0

[1, 2, [3,4]].2.0

Dict construction

PY & LS

LS

quotes of the keywords are optional

use object to simulate Python dict in LiveScript.

Dict construction(cont.)

PY & LS

LS

another better represent way

use object to simulate Python dict in LiveScript.

Dict Property Access

{‘a’:1, ‘b’}[‘a’]PY & LS

LS {‘a’:1, ‘b’}.a

unpacking function arguments

LS

PY

unpacking function keyword argument

LS

PY

packing function arguments

PY

LS

packing function keyword arguments

PY

LS

destructing assignment

PY & LS

LS

destructing assignment (cont.)

LS

Python does not support.

destructing function arguments

LS

Python does not support.

List Comprehension

PY

LS

result: [‘a1', 'a2', 'b1', 'b2']

Dict Comprehension

PY

LS

result: {‘a': 2, 'b': 4}

File Reading

⼤大家 !好 !我是 ! [Name]

file: memo.txt

PY

File Reading(cont.)

callback 2

callback 1

LS

Backcallcallback1

callback2

LS

Backcall(cont.)

LS

LS

Class

PY

Class(cont.)

LS

… means arguments of current function

Python Super

• super(type, obj) -> bound super object; requires isinstance(obj, type)

LiveScript Super

• is a reference to the appropriate function.

• If you want to call it with all arguments, use super …

• … implies calling it with the arguments of the current function.

LiveScript Mixing

You can extend only 1 parent but can implement many interface.

Many more…

LS Curried Function

Many more…

LS

Conclusion• change mind to code with callbacks.

• functional style programming with prelude.ls

• use class rarely after use LiveScript.

• LiveScript does not have debugger now, testing is highly important!

• You may need to check compiled JavaScript even your LiveScript code are correctly rarely.

Questions?