effin: A Typeable-free implementation of extensible effects

This package implements extensible effects, and alternative to monad transformers. The original paper can be found at http://okmij.org/ftp/Haskell/extensible/exteff.pdf. The main differences between this library and the one described in the paper are that this library does not use the Typeable type class, and has a simpler API for handling effects.

For example, the following code implements a handler for exceptions:

runException :: Effect (Exception e ': es) a -> Effect es (Either e a)
runException =
    handle (\x -> return (Right x))
    $ eliminate (\(Exception e) -> return (Left e))
    $ defaultRelay

Compare this to the corresponding code in extensible-effects:

runExc :: Typeable e => Eff (Exc e :> r) a -> Eff r (Either e a)
runExc = loop . admin
  where
    loop (Val x) = return (Right x)
    loop (E u)   = handleRelay u loop (\(Exc e) -> return (Left e))

In particular:

• Effect implementors are not required to do any recursion.

• The functions for writing effect handlers can be easily composed.

Modules

[Index]

Flags

Manual Flags

Name	Description	Default
mtl	Enable MTL support	Enabled

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

Downloads

• effin-0.1.0.1.tar.gz [browse] (Cabal source package)
• Package description (as included in the package)

Maintainer's Corner

Package maintainers

• AnthonyVandikas

For package maintainers and hackage trustees

• edit package information

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