free-category: efficient data types for free categories and arrows

[ algebra, category, category-theory, control, library, monads, mpl ] [ Propose Tags ]

Provide various data types for free categories / type aligned queues, type classes which allow to write abstract categories with side effects (Kleisli like categories). These are useful for encoding type safe state machines. Free arrows are also provided.

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Dependencies base (>=4.9 && <5), free-algebras (>= [details]
License MPL-2.0
Copyright (c) 2018-2019 Marcin Szamotulski
Author Marcin Szamotulski
Category Algebra, Control, Monads, Category
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Source repo head: git clone
Uploaded by coot at 2019-12-06T11:57:32Z
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Status Hackage Matrix CI
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Last success reported on 2019-12-06 [all 1 reports]


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Free Category

Maintainer: coot CircleCI

This package contains efficient implementations of free categories. There are various representations available:

  • real-time queues (C. Okasaki 'Pure Functional Data Structures')
  • type aligned lists
  • continuation passing style (Church encoding)

Free arrows and free Kleisli categories are also included.

Free categories are useful to model state machines in a simple yet type safe manner. For that purpose Kleisli categories are a very useful target which allows to include monadic computations. This package contains a useful generalisation of Kliesli categories captured by EffectCategory class (categories with effects), and a (free) transformer which lifts a category to a category with effects.


Check performance characteristics of various representations: