free-functors: Provides free functors that are adjoint to functors that forget class constraints.

[ bsd3, data, library, math ] [ Propose Tags ]

A free functor is a left adjoint to a forgetful functor. It used to be the case that the only category that was easy to work with in Haskell was Hask itself, so there were no interesting forgetful functors.

But the new ConstraintKinds feature of GHC provides an easy way of creating subclasses of Hask. That brings interesting opportunities for free (and cofree) functors.

The examples directory contains an implementation of non-empty lists as free semigroups, and automata as free actions. The standard example of free higher order functors is free monads, and this definition can be found in Data.Functor.HFree.

Versions [faq] 0, 0.1, 0.1.1, 0.1.2, 0.2, 0.3, 0.4, 0.4.1, 0.5, 0.6, 0.6.1, 0.6.1.1, 0.6.2, 0.6.3, 0.6.3.1, 0.6.3.2, 0.6.3.3, 0.6.4, 0.6.4.1, 0.6.5, 0.7, 0.7.1, 0.7.2, 0.8, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.9, 1.0, 1.0.1
Dependencies base (>=4.4 && <5), comonad (==3.0.*), constraints (>=0.3.2 && <0.4), transformers (>=0.2.0.0 && <0.4), void (>=0.4 && <0.6) [details]
License BSD-3-Clause
Author Sjoerd Visscher
Maintainer sjoerd@w3future.com
Category Data, Math
Home page https://github.com/sjoerdvisscher/free-functors
Bug tracker https://github.com/sjoerdvisscher/free-functors/issues
Source repo head: git clone git://github.com/sjoerdvisscher/free-functors.git
Uploaded by SjoerdVisscher at Sat Jul 28 18:16:05 UTC 2012
Distributions NixOS:1.0.1
Downloads 11118 total (215 in the last 30 days)
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