Portability | non-portable (multi-param classes, functional dependencies) |
---|---|

Stability | experimental |

Maintainer | libraries@haskell.org |

The MonadWriter class.

Inspired by the paper /Functional Programming with Overloading and Higher-Order Polymorphism/, Mark P Jones (http://web.cecs.pdx.edu/~mpj/pubs/springschool.html) Advanced School of Functional Programming, 1995.

# Documentation

class (Monoid w, Monad m) => MonadWriter w m | m -> w whereSource

(Monoid w, Monad m, MonadTrans t, Monad (t (WriterT w m)), Monad (t (StateT w m))) => MonadWriter w (t (WriterT w m)) | |

(Monoid w, MonadTrans t, Monad (t (Writer w)), Monad (t (State w))) => MonadWriter w (t (Writer w)) | |

Monoid w => MonadWriter w (Writer w) | |

(Monoid w, Monad m, MonadTrans t, Monad (t (WriterT w m)), Monad (t (StateT w m))) => MonadWriter w (t (WriterT w m)) | |

(Monoid w, MonadTrans t, Monad (t (Writer w)), Monad (t (State w))) => MonadWriter w (t (Writer w)) | |

Monoid w => MonadWriter w (Writer w) | |

(Monoid w, Monad m) => MonadWriter w (WriterT w m) | |

(Monoid w, Monad m) => MonadWriter w (WriterT w m) |

listens :: MonadWriter w m => (w -> b) -> m a -> m (a, b)Source

censor :: MonadWriter w m => (w -> w) -> m a -> m aSource