Implementation of supermonads for GHC. See the Supermonads: One Notion to Bind Them All paper for detailed explanation of version 0.1. An updated version of the paper that also explains superapplicatives has been submitted to JFP.
The library offers two definitions for supermonads. The version
in Control.Super.Monad does not have support for constrained
monads. The version in Control.Super.Monad.Constrained has
support for constrained monads. The different versions are
provided, because working with the additional constraints
required for constrained monads can be cumbersome sometimes.
We want to offer people a possibility to experiment with supermonads
without having to bother with these constraints, if they don't need
constrained monads. If you have any feedback or suggestions for
improvement from you usage of supermonads, please leave them on
the GitHub bug tracker or write an email to the maintainer.
These parallel structures will not be maintained indefinitely and
at some point we will probably only offer supermonads with support
for constrained monads.
Support for generalized applicatives was added in version 0.2. For users this does not change anything.
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The implementation has been tested with GHC in version 7.10.3, 8.0.2 and 8.2.1.
Versions of GHC prior to version 7.10.1 will most certainly not work, because the plugin mechanism was still in development.
Newer version of GHC may work. If you encounter problems with a newer version of GHC, please file a bug report so it can be fixed.
To use supermonads in a module you need to do the following:
-
Enable
RebindableSyntaxin your module by using theLANGUAGEpragma:{-# LANGUAGE RebindableSyntax #-} -
Enable the plugin in that modules using the the
OPTIONS_GHCpragma:{-# OPTIONS_GHC -fplugin Control.Super.Monad.Plugin #-} -
Import the supermonad prelude
Control.Super.Monad.Prelude. If you choose to work with constrained monads you will need to importControl.Super.Monad.Constrained.Preludeinstead. -
Make sure to compile the module with the
-dynamicflag. This is required for GHC's plugin mechanism to work properly.
If you file a bug report, please always include the version of GHC you are working with and a minimal example that shows the problem.
Examples for the use of the plugin with different kinds of monad generalizations
are provided in the examples directory. All examples have their own separate
cabal file and offer a version of the code with and without the use of supermonads.
A minimal example of how to use supermonads can be found under examples/monad/minimal.
It is a good entry point to play around with supermonads.