Difference between revisions of "Functional Reactive Programming"
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Functional Reactive Programming (FRP) integrates time flow and compositional events into functional programming. This provides an elegant way to express computation in domains such as interactive animations, robotics, computer vision, user interfaces, and simulation. |
Functional Reactive Programming (FRP) integrates time flow and compositional events into functional programming. This provides an elegant way to express computation in domains such as interactive animations, robotics, computer vision, user interfaces, and simulation. |
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+ | |||
+ | |||
+ | == Introduction == |
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+ | |||
+ | FRP is about domain-specific languages that capture the notion of |
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+ | time-varying values. Let's take Netwire 4 as an example. You can install it either from HackageDB, |
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+ | |||
+ | cabal install netwire |
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+ | |||
+ | or by grabbing the latest source code via darcs: |
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+ | |||
+ | darcs get http://darcs.ertes.de/netwire/ |
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+ | cd netwire |
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+ | cabal install |
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+ | |||
+ | Imagine you have a simple GUI label that displays the number of seconds |
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+ | passed since program start. In an event-based model this is actually |
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+ | quite a complicated task. You would have to create a label and update |
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+ | it all the time using some form of timer/idle event. In Netwire you |
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+ | write: |
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+ | |||
+ | myLabel = time |
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+ | |||
+ | Now let's say you want to have the same GUI, but the time should start |
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+ | at 10 and pass twice as fast, so you actually want to display twice the |
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+ | number of seconds passed plus 10: |
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+ | |||
+ | myLabel = 10 + 2*time |
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+ | |||
+ | Imagine you want to display the string "yes" in a label: |
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+ | |||
+ | myLabel = "yes" |
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+ | |||
+ | Now let's say you want to display "yes", when the space key is held down |
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+ | and "no" otherwise: |
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+ | |||
+ | myLabel = "yes" . keyDown Space <|> "no" |
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+ | |||
+ | You want to display time while pressed and "Press space" while not: |
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+ | |||
+ | myLabel = fmap show time . keyDown Space <|> "Press space" |
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+ | |||
+ | You want to display "yes" every other second and "no" otherwise: |
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+ | |||
+ | myLabel = "yes" . holdFor 1 (periodically 2) <|> "no" |
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+ | |||
+ | Imagine doing that with event-based code. |
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+ | |||
+ | Summary: FRP is about handling time-varying values like they were |
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+ | regular values. |
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== Libraries == |
== Libraries == |
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− | * [http:// |
+ | * [http://hackage.haskell.org/package/sodium Sodium] |
* [[Grapefruit]] |
* [[Grapefruit]] |
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* [[Reactive]] |
* [[Reactive]] |
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* [[WxFruit|wxFruit]] |
* [[WxFruit|wxFruit]] |
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* [http://hackage.haskell.org/package/elerea Elerea] |
* [http://hackage.haskell.org/package/elerea Elerea] |
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+ | * [[Reactive-banana|reactive-banana]] |
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+ | * [[Netwire]] |
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+ | * [http://conal.net/fran/ Fran] (discontinued) |
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+ | * [http://hackage.haskell.org/packages/archive/pkg-list.html#cat:frp Hackage packages in the category FRP] |
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+ | |||
+ | |||
+ | == Publications and talks == |
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+ | * [http://www.cs.rit.edu/~eca7215/frp-independent-study/Survey.pdf A Survey of Functional Reactive Programming] |
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⚫ | |||
⚫ | |||
+ | * [http://haskell.cs.yale.edu/?page_id=65#FunctionalReactiveProgramming The Yale Haskell Group’s FRP-related publications] |
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+ | |||
+ | |||
⚫ | |||
+ | * [http://apfelmus.nfshost.com/blog.html#functional-reactive-programming-frp FRP-related posts on Heinrich Apfelmus’ blog] |
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⚫ | |||
+ | * [http://jeltsch.wordpress.com/tag/frp/ FRP-related posts on Wolfgang Jeltsch’s blog] |
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⚫ | |||
+ | * [http://blog.edwardamsden.com/2011/03/demonstrating-time-leak-in-arrowized.html Demonstrating a Time Leak in Arrowized FRP] by Edward Amsden |
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− | == Material == |
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⚫ | |||
⚫ | |||
− | * [http://www.haskell.org/yale/publications.html The Yale Haskell group’s latest publications] (mostly related to FRP) |
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== People == |
== People == |
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+ | * [http://apfelmus.nfshost.com/ Heinrich Apfelmus] |
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− | * [http://www. |
+ | * [http://www.facebook.com/antony.courtney Antony Courtney] |
* [http://conal.net/ Conal Elliott] |
* [http://conal.net/ Conal Elliott] |
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− | * [http:// |
+ | * [http://sgate.emt.bme.hu/patai/ Patai Gergely] |
+ | * [http://www.ittc.ku.edu/csdl/fpg/Users/AndyGill Andy Gill] |
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* Liwen Huang |
* Liwen Huang |
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* Paul Hudak |
* Paul Hudak |
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− | * Wolfgang Jeltsch |
+ | * [https://wolfgang.jeltsch.info/ Wolfgang Jeltsch] |
* [http://www.cs.nott.ac.uk/~nhn/ Henrik Nilsson] |
* [http://www.cs.nott.ac.uk/~nhn/ Henrik Nilsson] |
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* [http://mcis.western.edu/~jpeterson/ John Peterson] |
* [http://mcis.western.edu/~jpeterson/ John Peterson] |
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− | * Patai Gergely |
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+ | [[Category:FRP|*]] |
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⚫ | |||
⚫ | |||
⚫ |
Revision as of 16:24, 16 November 2012
Functional Reactive Programming (FRP) integrates time flow and compositional events into functional programming. This provides an elegant way to express computation in domains such as interactive animations, robotics, computer vision, user interfaces, and simulation.
Introduction
FRP is about domain-specific languages that capture the notion of time-varying values. Let's take Netwire 4 as an example. You can install it either from HackageDB,
cabal install netwire
or by grabbing the latest source code via darcs:
darcs get http://darcs.ertes.de/netwire/ cd netwire cabal install
Imagine you have a simple GUI label that displays the number of seconds passed since program start. In an event-based model this is actually quite a complicated task. You would have to create a label and update it all the time using some form of timer/idle event. In Netwire you write:
myLabel = time
Now let's say you want to have the same GUI, but the time should start at 10 and pass twice as fast, so you actually want to display twice the number of seconds passed plus 10:
myLabel = 10 + 2*time
Imagine you want to display the string "yes" in a label:
myLabel = "yes"
Now let's say you want to display "yes", when the space key is held down and "no" otherwise:
myLabel = "yes" . keyDown Space <|> "no"
You want to display time while pressed and "Press space" while not:
myLabel = fmap show time . keyDown Space <|> "Press space"
You want to display "yes" every other second and "no" otherwise:
myLabel = "yes" . holdFor 1 (periodically 2) <|> "no"
Imagine doing that with event-based code.
Summary: FRP is about handling time-varying values like they were regular values.
Libraries
- Sodium
- Grapefruit
- Reactive
- DataDriven
- Yampa
- wxFruit
- Elerea
- reactive-banana
- Netwire
- Fran (discontinued)
- Hackage packages in the category FRP
Publications and talks
- A Survey of Functional Reactive Programming
- Conal Elliott’s FRP-related publications
- Grapefruit-related publications and talks
- The Yale Haskell Group’s FRP-related publications
Blog posts
- FRP-related posts on Heinrich Apfelmus’ blog
- FRP-related posts on Conal Elliott’s blog
- FRP-related posts on Wolfgang Jeltsch’s blog
- Relative time FRP by Luke Palmer
- Demonstrating a Time Leak in Arrowized FRP by Edward Amsden
People
- Heinrich Apfelmus
- Antony Courtney
- Conal Elliott
- Patai Gergely
- Andy Gill
- Liwen Huang
- Paul Hudak
- Wolfgang Jeltsch
- Henrik Nilsson
- John Peterson