# Direction of data flow

### From HaskellWiki

In Haskell the direction of data flow symbolized by the notations differs amongst the notations. Both directions occur equally frequently:

from left to right:

function definition | f x = x*x |
(input left, output right) |

Lambda | \ x -> x*x | |

do notation | do f; g | |

monadic composition | f >>= g | |

let expression | let x = 2 in x*x |
(first definition, then usage) |

from right to left:

function application | f x f $ x |
(input right, applied function left) |

composition | g . f | |

results of monads | do x <- f | |

monadic composition | g =<< f | |

where clause | x*x where x = 2 |
(first usage, then definition) |

## 1 Weblinks

- http://www.haskell.org/pipermail/libraries/2005-August/004315.html
- http://www.iba-cg.de/doc/hal1-haskell-with-style.pdf

## 2 See also

There is still something to translate from De/Flussrichtung