Arc (programming language)
|This article relies on references to primary sources. (March 2011)|
|Paradigm(s)||multi-paradigm: functional, procedural, reflective|
|Designed by||Paul Graham and Robert Morris|
|Stable release||3 (July 13, 2009)|
|Typing discipline||dynamic, strong|
|OS||Cross-platform, runs on the Racket compiler|
|License||Perl Foundation's Artistic License 2.0|
|Usual filename extensions||.arc|
In 2001 Paul Graham announced that he was working on a new dialect of Lisp named "Arc". Over the years since, he has written several essays describing features or goals of the language, and some internal projects at Y Combinator have been written in Arc, most notably the Hacker News web forum and news aggregator program.
It would not be far from the truth to say that a hacker about to write a program decides what language to use, at least subconsciously, based on the total number of characters he'll have to type. If this isn't precisely how hackers think, a language designer would do well to act as if it were.
According to Paul Graham, John McCarthy's original Lisp was built on a small set of "axioms". He wants Arc constructed in a similar way, even if that strips the language of features large organizations want. Specifically, Graham thinks object-orientation is not useful, as OO methods and patterns are just "good design". He sees language features used to implement OO as partially mistaken.
Lisp programmers disagree on how much S-expressions should be complemented by other forms of syntax. Graham thinks additional syntax should be used in situations where pure S-expressions would be too verbose, saying, "I don't think we should be religiously opposed to introducing syntax into Lisp." Graham also thinks efficiency problems should be solved by giving the programmer a good profiler.
Hello world in Arc :
(prn "Hello, World")
A program used by Paul Graham to illustrate Arc's terseness. It produces at the url "/said" a form with one field. When the form is submitted, it leads to a page with a link that says "click here", which itself leads to a page with the value of the original input field.
(defop said req (aform [onlink "click here" (pr "you said: " (arg _ "foo"))] (input "foo") (submit)))
The first publicly released version of Arc was made available on 29 January 2008, implemented on top of Racket ("PLT-Scheme" at that time). The release comes in the form of a .tar archive, containing the Racket source code for Arc. A tutorial and a discussion forum are also available. The forum uses the same program that news.ycombinator.com does, and is itself written in Arc.
Due to the slow development of the official Arc branch, some members of the Arc community started unofficial repositories with unofficial emendations, extensions and libraries. One version, Anarki, permitted  anyone to submit changes to the project. The community-managed wiki is a better source of information than the official site at this point.
- Arc at 3 Weeks (Paul Graham)
- Essay:Being Popular
- Why Arc Isn't Especially Object-Oriented
- Arc FAQ
- Take the Arc challenge
- Arc's Out (29 January 2008)
- discussion forum
- Anarki Repository on Github
- May 2013 announcement: anarki is no longer world-committable
- The arc language wiki
- Rainbow, an implementation of Arc in java by Conan Dalton