cabal-version:  2.4
name:           acts
version:        0.3.1.0
x-revision: 2
synopsis:       Semigroup actions and torsors.
category:       Algebra, Math
license:        BSD-3-Clause
build-type:     Simple
author:         Sam Derbyshire
maintainer:     Sam Derbyshire
homepage:       https://github.com/sheaf/acts
bug-reports:    https://github.com/sheaf/acts/issues
extra-source-files:
    changelog.md
extra-doc-files:
    img/*.svg
description:
  Acts and torsors model types which can be transformed under the action of another type.
  .
  A prototypical example is affine space, which has an action by translation:
  given any two points in affine space, there is a unique translation that brings one to the other.
  .
  This can be useful in a library keeping track of time: on top of needing to keep track
  of units, one also needs to distinguish between absolute time (time stamps) and relative time
  (time differences).
  The operations one expects in this situation are:
  .
  * Addition and subtraction of time differences: time differences form a (commutative) group.
  * Translation of an absolute time by a time difference: there is an action of relative time on absolute time.
  * Given two absolute times, one can obtain the time difference between them: absolute time is a torsor under relative time.
  .
  This library provides a convenient framework which helps to avoid mixing up these two different notions.
  .
  .
  A fleshed out example is available at "Acts.Examples.MusicalIntervals",
  which showcases the use of actions and torsors in the context of musical intervals and harmony.
  It also demonstrates common usage patterns of this library, such as how to automatically derive instances.
  .
  See also the [project readme](https://github.com/sheaf/acts),
  which includes a simple example with 2D affine space.

source-repository head
  type: git
  location: git://github.com/sheaf/acts.git

flag finitary
  description:
    Use the 'finitary' library to define actions on finite enumerations.
    .
    Disable to remove dependencies on `finite-typelits` and `finitary`.
  default: True
  manual: False

common common

  build-depends: 
      base
        >= 4.12 && < 4.17
    , groups
        ^>= 0.4.0.0

  if flag(finitary)
    cpp-options:
        -DFIN
    build-depends:
        finitary
          >= 1.2.0.0 && < 2.2
      , finite-typelits
          ^>= 0.1.4.2

  default-language:
      Haskell2010

  ghc-options:
      -O2
      -Wall
      -Wcompat
      -fwarn-missing-local-signatures
      -fwarn-incomplete-uni-patterns
      -fwarn-missing-deriving-strategies


library

  import:
      common

  hs-source-dirs:
      src

  exposed-modules:
      Data.Act

  build-depends:
      deepseq
        ^>= 1.4.4.0


library acts-examples

  import:
      common

  hs-source-dirs:
      examples

  exposed-modules:
      Acts.Examples.MusicalIntervals

  build-depends:
      acts