Dunai-core

This repository implements a generalized version of reactive programming, on top of which other variants like Yampa, Classic FRP and Reactive Values can be implemented. It is a fork of dunai and just contains the core library, with a few minor modifications. The main reason this fork exists is as a dependency for rhine, where support for GHC 8.6 and current stack nightly is wanted. It might disappear in the future. If in doubt, you should choose dunai over dunai-core.

Installation

Cabal

$ cabal sandbox init         # Optional, but recommended
$ cabal update
$ cabal install dunai

stack

$ git clone https://github.com/turion/dunai-core
$ cd dunai-core
$ stack build

Dependencies

Dunai currently support GHC versions 8.2.1 to 8.6.

Examples

To test Dunai:

• Use embed :: MSF m a b -> [a] -> m [b] to collect a list with the results.

• Use embed_ :: MSF m a () -> [a] -> m () to perform side effects without collecting the results.

• Use reactimate :: MSF m () () -> m () when data is collected/provided by the MSF itself.

ghci> import Data.MonadicStreamFunction
ghci> embed (arr (+1)) [1,2,3,4,5]
[2,3,4,5,6]
ghci> embed_ (arr (+1) >>> liftS print) [1,2,3,4,5]
2
3
4
5
6
ghci> reactimate (arrM_ getLine >>> arr reverse >>> liftS putStrLn)
Hello
olleH
Haskell is awesome
emosewa si lleksaH
^C

Further reading

The best introduction to the fundamentals of Monadic Stream Functions is:

• Functional Reactive Programming, Refactored (official ACM page) (mirror)

The following papers are also related to MSFs:

• Back to the Future: time travel in FRP (mirror)

• Testing and Debugging Functional Reactive Programming

About the name

Dunai (aka. Danube, or Дунай) is one of the main rivers in Europe, originating in Germany and touching Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova and Ukraine.

Other FRP libraries, like Yampa, are named after rivers. Dunai has been chosen due to the authors' relation with some of the countries it passes through, and knowing that this library has helped unite otherwise very different people from different backgrounds.