Editing Fudgets

{{Infobox software
| name = Fudgets
| logo =
| screenshot =
| screenshot alt =
| caption =
| author = Thomas Hallgren,<br/>Magnus Carlsson
| released = {{Start date and age|1993|06}}
| latest release version = 0.18.4
| latest release date = {{Start date and age|2023|06}}
| latest preview version =
| latest preview date =
| programming language = [[Haskell]]
| operating system = [[POSIX]] compatible: [[Unix]], [[Unix-like]], [[Linux]], [[macOS]] via [[XQuartz]]
| platform = [[IA-32]], [[x86-64]]
| size =
| language = [[English language|English]]
| genre = [[Graphical user interface|GUI]] [[toolkit]]
| license = [[freeware]] non-commercial
}}

In [[computing]], '''Fudgets''' is a [[graphical user interface]] [[toolkit]] for the [[Functional programming|functional]] [[programming language]] [[Haskell]] and the [[X Window System]].<ref>{{Cite book |last1=Hallgren |first1=Thomas |last2=Carlsson |first2=Magnus |date=1995 |title=Advanced Functional Programming |chapter=Programming with Fudgets |editor1-last=Jeuring |editor1-first=Johan |editor2-last=Meijer |editor2-first=Erik |chapter-url=https://link.springer.com/chapter/10.1007/3-540-59451-5_5 |series=Lecture Notes in Computer Science |volume=925 |language=en |location=Berlin, Heidelberg |publisher=Springer |pages=137–182 |doi=10.1007/3-540-59451-5_5 |isbn=978-3-540-49270-2}}</ref><ref>{{Cite book |last1=Reid |first1=Alastair |date=1994 |chapter=Implementing Fudgets with Standard Widget Sets |url=https://doi.org/10.1007/978-1-4471-3236-3_18 |title=Functional Programming, Glasgow 1993: Proceedings of the 1993 Glasgow Workshop on Functional Programming, 5–7 July 1993 |place=Ayr, Scotland |pages=222–235 |editor1-last=O’Donnell |editor1-first=John T. |last2=Singh |first2=Satnam |editor2-last=Hammond |editor2-first=Kevin |access-date=2023-10-26 |series=Workshops in Computing |publication-place=London |publisher=Springer |language=en |doi=10.1007/978-1-4471-3236-3_18 |isbn=978-1-4471-3236-3}}</ref> Fudgets makes it easy to create [[client–server model]] applications that communicate via the [[Internet]].

Most of the work on Fudgets was done in 1991-1996 by Thomas Hallgren and Magnus Carlsson.<ref>{{Cite web |last1=Hallgren |first1=Thomas |last2=Carlsson |first2=Magnus |date=June 6, 2023 |title=Fudgets Home Page |url=http://www.altocumulus.org/Fudgets/ |access-date=October 25, 2023 |website=altocumulus.org}}</ref>

The authors claim that many of the advantages of Fudgets come from it being programmed in a [[Strict programming language|lazy]] [[functional programming]] language.<ref>{{Cite book |last1=Carlsson |first1=Magnus |last2=Hallgren |first2=Thomas |date=1993-07-01 |title=Proceedings of the conference on Functional programming languages and computer architecture |chapter=Fudgets: A graphical user interface in a lazy functional language |chapter-url=https://dl.acm.org/doi/10.1145/165180.165228 |language=en |publisher=ACM |pages=321–330 |doi=10.1145/165180.165228 |isbn=978-0-89791-595-3|s2cid=9943994}}</ref>

The main entity of toolkit is fudget (implemented on low level through stream processors) which has its own input and output.<ref>{{Cite journal |last1=Burton |first1=F. Warren |date=1999 |title=Advanced Functional Programming: Lecture Notes in Computer Science 925 edited by Johan Jeuring and Erik Meijer, Springer-Verlag, 1995. |url=https://www.cambridge.org/core/journals/journal-of-functional-programming/article/advanced-functional-programming-lecture-notes-in-computer-science-925-edited-by-johan-jeuring-and-erik-meijer-springerverlag-1995/F1EEA48458E15F0D5929E41543BB2848 |journal=Journal of Functional Programming |language=en |volume=9 |issue=1 |pages=105–111 |doi=10.1017/S0956796899223246 |issn=1469-7653|url-access=subscription }}</ref> Fudgets can be composed in parallel or sequence, yielding new fudget which can be used in code as any other fudget.

== Example ==
<syntaxhighlight lang="haskell">
factorialF  = stdoutF >==< mapF (show . factorial . read) >==< stdinF
factorial   :: Integer -> Integer
factorial n = product [1..n]
</syntaxhighlight>

The code is self-describing considering that <code>>==<</code> is sequential fudget plumbing and <code>mapF</code> is fudget that takes a function of one argument and makes a fudget which output is input applied to that function. Fudget composition must be read from right to left, as a simple function composition. Now you can simply write:
<syntaxhighlight lang="haskell">
main = fudlogue factorialF
</syntaxhighlight>

compile and run. For every given integer value it will print its factorial.

== License ==
The [[software license]] of Fudgets claims that this software is [[freeware]] for non-commercial use only.

== References ==
{{Reflist}}

== External links ==
*{{Official website|www.altocumulus.org/Fudgets}}, latest release marked January 13, 2016
*[http://www.cse.chalmers.se/~hallgren/Thesis/  Fudgets Phd thesis by Hallgren and Carlsson]

{{Haskell programming}}

[[Category:Widget toolkits]]
[[Category:X-based libraries]]
[[Category:Haskell software]]
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