View source for Claire (programming language)

{{Infobox programming language
| name                   = Claire
| file_ext               = <code>.cl</code>
| paradigm               = multi-paradigm: [[Functional programming|functional]], [[Object-oriented programming|object-oriented]] ([[Class (computer programming)|class-based]]), [[Production system (computer science)|rule processing]], [[Reflection (computer programming)|reflective]]
| year                   = {{start date|1994}}
| designer               = Yves Caseau
| latest_release_version = 3.3.46
| latest_release_date    = {{start date and age|2009|2|17}}
| typing                 = strong, both static and dynamic
| implementations        = Claire ([[Reference implementation|reference implementation]]), WebClaire
| influenced_by          = [[Smalltalk]], [[SETL]], [[OPS5]], [[Lisp (programming language)|Lisp]], [[ML (programming language)|ML]], [[C (programming language)|C]], LORE, LAURE
| operating_system       = Cross-platform
| license                = Permissive free software licence
}}
'''Claire''' is a high-level [[Functional programming|functional]] and [[Object-oriented programming|object-oriented]] [[Programming language|programming language]] with [[Production system (computer science)|rule processing]] abilities. It was designed by Yves Caseau at Bouygues' e-Lab research laboratory, and received its final definition in 2004.

Claire provides:
*A simple object system with parametric [[Class (computer programming)|classes]] and methods
*Polymorphic and parametric functional programming
*[[Production system (computer science)|Production rules]] triggered by [[Event condition action|events]]
*Versioned snapshots of the state of the whole system, or any part, supporting [[Rollback (data management)|rollback]] and easy exploration of [[Search algorithm|search spaces]]
*Explicit relations between entities; for example, two entities might be declared inverses of one another
*First-class [[Set (abstract data type)|sets]] with convenient [[Philosophy:Syntax|syntax]] for set-based programming
*An expressive set-based type system allowing both [[Higher-order programming|second-order]] static and dynamic typing

Claire's [[Reference implementation|reference implementation]], consisting of an interpreter and compiler, was fully open-sourced with the release of version 3.3.46 in February 2009. Another implementation, WebClaire, is commercially supported.

Claire has, since 2022, a new reference version, CLAIRE4, which is written on top of the [[Go (programming language)|Go programming language]]. It has a [https://sites.google.com/view/claire4/home new website] with documentations and examples, together with a [https://github.com/ycaseau/CLAIRE4 Github] open source repository.

==Overview==
Claire is a [[General-purpose programming language|general-purpose programming language]], best suited to application software requiring sophisticated [[Data modeling|data modeling]], rule processing or problem solving. WebClaire adds extensions for fuller integration with the [[Operating system|operating system]] and for programming [[Web application|web application]]s.

Though Claire can be used for complete projects, it is designed to integrate smoothly with [[C++]], [[Java (programming language)|Java]] or [[Go (programming language)|Go]].

The key set of features that distinguishes Claire from other programming languages has been dictated by experience in solving complex optimization problems. Two features not found in other mixed functional/object-oriented languages, such as [[OCaml]], [[Scala (programming language)|Scala]] and [[F Sharp (programming language)|F#]], are ''versioning'' and ''production rules''.

Versions can be viewed as a stack of snapshots of some part of the system, which can be made as large (for expressiveness) or small (for efficiency) as necessary. Creation and roll-back of versions permit [[Backtracking|backtracking]], as found in [[Logic programming|logic programming]], though Claire's backtracking may cover any user-defined structure rather than just a set of logic variables.

A production rule in Claire is composed of an event, a condition and a response to be evaluated if the condition is satisfied. An event may be any change in an object's slot or the instantiation of a class, and a response may itself set off further events. Such production rules are especially useful in describing reactive algorithms, such as those for [[Constraint programming|constraint]] propagation.

Claire was created as a successor to LAURE, an expressive but complex language designed by Caseau in the 1980s that combined many paradigms. Claire was intended to be both easier to learn than its predecessor and to impose no performance overhead relative to C++; it is thus a much smaller language, omitting features such as [[Constraint satisfaction|constraints]] and [[Deductive language|deductive]] rules, and is closer to [[C (programming language)|C]] in spirit and syntax. Its main users in industry have been the Bouygues and Thales groups. The new CLAIRE 4 release bring both a new level of reliability - borrowing of Go's strength as the underlying language, and improved performance both for the compiler and interpreter.

==Example==
A function to compute the ''n''th Fibonacci number:

 fib(n:integer) : integer
 -> (if (n < 2) 1
 else fib(n - 1) + fib(n - 2))

==External links==
*The latest version of Claire and its documentation are available from [https://github.com/ycaseau/CLAIRE4 Github repository] and the [https://sites.google.com/view/claire4/home CLAIRE4 Website].
*[https://web.archive.org/web/20111001163413/http://www.claire-language.com/pub/trunk/xl/doc/claire.index.html Documentation]  for Claire and WebClaire.
*"[https://web.archive.org/web/20110607212054/http://www.dcs.gla.ac.uk/~pat/cp4/claire/Claire_3.2.pdf Introduction to the CLAIRE Programming Language Version 3.2]" by Yves Caseau and François Laburthe.
*"[http://trac.claire-language.com/cgi-bin/trac.cgi/raw-attachment/wiki/Papers/combi_set_search_rules_algo.pdf CLAIRE: Combining Sets, Search and Rules to Better Express Algorithms]{{dead link|date=August 2017 |bot=InternetArchiveBot |fix-attempted=yes }}" by Yves Caseau, François-Xavier Josset and François Laburthe (2002). A 26-page overview, intended for an academic audience, with benchmarks.


[[Category:Experimental programming languages]]
[[Category:Functional languages]]
[[Category:Multi-paradigm programming languages]]
[[Category:Object-oriented programming languages]]

{{Sourceattribution|Claire (programming language)}}