Editing LiveScript (programming language)

{{Short description|Functional programming language}}
{{for|the primary web scripting language initially known as LiveScript|JavaScript}}
{{Primary sources|date=May 2015}}
{{Infobox programming language
| name = LiveScript
| paradigms = [[Programming paradigm|multi-paradigm]], [[Functional programming|functional]], [[Object-oriented programming|object-oriented]]
| designers = [[Jeremy Ashkenas]], Satoshi Murakami, George Zahariev
| developers = (same)
| year = {{Start date and age|2011}}
| latest release version = 1.6.1
| latest release date = {{Start date and age|df=yes|2020|07|14}}<ref>{{cite web |url=https://github.com/gkz/LiveScript/tags |title=LiveScript Releases |website=[[GitHub]] |access-date=21 February 2021}}</ref>
| typing = [[Dynamic typing|dynamic]], [[Strong and weak typing|weak]]
| scope = [[Scope (computer science)|Lexical]]
| operating system = [[Cross-platform software|Cross-platform]]
| license = [[MIT License|MIT]]
| website = {{URL|livescript.net}}
| file ext = <code>.ls</code>
| influenced by = [[JavaScript]], [[Haskell]], [[CoffeeScript]], [[F Sharp (programming language)|F#]]
}}

'''LiveScript''' is a [[Functional programming|functional]] [[programming language]] that [[Source-to-source compiler|transpiles]] to [[JavaScript]]. It was created by [[Jeremy Ashkenas]], the creator of [[CoffeeScript]], along with Satoshi Muramaki, George Zahariev, and many others.<ref>{{cite web |url=https://github.com/gkz/LiveScript/graphs/contributors |title=LiveScript contributors page |website=[[GitHub]] |access-date=20 June 2015}}</ref> (The name may be a homage to the beta name of JavaScript; for a few months in 1995, it was called LiveScript before the official release.<ref>{{cite web |url=https://speakingjs.com/es5/ch04.html |title=Chapter 4. How JavaScript Was Created |website=speakingjs.com |access-date=2017-11-21 |url-status=live |archive-url=https://web.archive.org/web/20200227184037/https://speakingjs.com/es5/ch04.html |archive-date=2020-02-27}}</ref>)

== Syntax ==
LiveScript is an indirect descendant of [[CoffeeScript]].<ref>{{cite web |url=http://livescript.net/ |title=LiveScript - a language which compiles to JavaScript}}</ref> The following [["Hello, World!" program]] is written in LiveScript, but is also compatible with Coffeescript:

<syntaxhighlight lang="livescript">
hello = ->
  console.log 'hello, world!'
</syntaxhighlight>

While calling a function can be done with empty parens, <code>hello()</code>, LiveScript treats the exclamation mark as a single-character shorthand for function calls with zero arguments: <code>hello!</code>

LiveScript introduces a number of other incompatible idioms:

=== Name mangling ===
At compile time, the LiveScript parser implicitly converts [[kebab case]] (dashed variables and function names) to [[camel case]].

<syntaxhighlight lang="livescript">
hello-world = ->
  console.log 'Hello, World!'
</syntaxhighlight>

With this definition, both the following calls are valid. However, calling using the same dashed syntax is recommended.

<syntaxhighlight lang="output">
hello-world!
helloWorld!
</syntaxhighlight>

This does not preclude developers from using camel case explicitly or using [[snake case]]. Dashed naming is however, common in idiomatic LiveScript<ref>{{cite web |url=http://www.preludels.com/ |title=prelude.ls - a functionally oriented utility library in LiveScript}}</ref>

=== Pipes ===
{{Further|Anonymous pipe|Named pipe|Pipeline (Unix)}}
A [[Anonymous pipe|pipe operator]] <code>|></code> passes the result of an expression on the left of the operator as an argument to the expression on the right of it. LiveScript supports these, as do some other functional languages such as [[F Sharp (programming language)|F#]] and [[Elixir (programming language)|Elixir]]; the argument passed in F# is the last one, but in Elixir is the first one.

<syntaxhighlight lang="livescript">
"hello!" |> capitalize |> console.log
# > Hello!
</syntaxhighlight>

=== Operators as functions ===
When parenthesized, operators such as <code>not</code> or <code>+</code> can be included in pipelines or called as if they are functions.

<syntaxhighlight lang="livescript">
111 |> (+) 222
# > 333

(+) 1 2
# > 3
</syntaxhighlight>

==References==
{{Reflist}}

== External links ==
* {{Official website}}

{{JavaScript}}
[[Category:JavaScript programming language family]]
[[Category:Software using the MIT license]]
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