name:               validation
version:            0.5.0
x-revision: 1
license:            BSD3
license-file:       LICENSE
author:             Tony Morris <ʇǝu˙sıɹɹoɯʇ@ןןǝʞsɐɥ> <dibblego>, Nick Partridge <nkpart>
maintainer:         Tony Morris <ʇǝu˙sıɹɹoɯʇ@ןןǝʞsɐɥ> <dibblego>, Nick Partridge <nkpart>
copyright:          Copyright (C) 2014,2015 NICTA Limited
synopsis:           A data-type like Either but with an accumulating Applicative
category:           Data
description:        
  <<http://i.imgur.com/Ns5hntl.jpg>>
  .
  Several data-types like Either but with differing properties and type-class
  instances.
  .
  Library support is provided for those different representations, include
  `lens`-related functions for converting between each and abstracting over their
  similarities.
  .
  * `AccValidation`
  .
  The `AccValidation` data type is isomorphic to `Either`, but has an instance
  of `Applicative` that accumulates on the error side. That is to say, if two
  (or more) errors are encountered, they are appended using a `Semigroup`
  operation.
  .
  As a consequence of this `Applicative` instance, there is no corresponding
  `Bind` or `Monad` instance. `AccValidation` is an example of, "An applicative
  functor that is not a monad."
  .
  * `Validation`
  .
  The `Validation` data type is isomorphic to `Either` and has a `Monad`
  instance that does the same as `Either`. The only difference to `Either` is
  the constructor names and surrounding library support.
  .
  * `ValidationT`
  .
  The `ValidationT` data type is the monad transformer for `Validation`. An
  instance of `MonadTrans` is provided for `(ValidationT err)`. Due to the
  arrangement of the `ValidationT` type constructor, which permits a `MonadTrans
  instance, there is no possible `Bifunctor` instance. Consequently, the
  `ValidationB` data type provides a `Bifunctor` instance (but not a
  `MonadTrans` instance). Library support is provided to exploit the isomorphism
  to `ValidationB`.
  .
  Note that since `AccValidation` is not a monad, there is also no corresponding
  monad transformer for this data type.
  .
  * `ValidationB`
  .
  The `ValidationB` data type is similar to the monad transformer for
  `Validation` (`ValidationT`), however, due to the arrangement of the
  `ValidationB` type constructor, which permits a `Bifunctor` instance, there is
  no possible `MonadTrans` instance. Consequently, the `ValidationT` data type
  provides a `MonadTrans` instance (but not a `Bifunctor` instance). Library
  support is provided to exploit the isomorphism to `ValidationT`.

homepage:           https://github.com/NICTA/validation
bug-reports:        https://github.com/NICTA/validation/issues
cabal-version:      >= 1.10
build-type:         Custom
extra-source-files: changelog

source-repository   head
  type:             git
  location:         git@github.com:NICTA/validation.git

flag                small_base
  description:      Choose the new, split-up base package.

library
  default-language:
                    Haskell2010

  build-depends:
                      base          >= 4.8 && < 5
                    , mtl           >= 2.0 && < 2.3
                    , semigroups    >= 0.8
                    , semigroupoids >= 4.0
                    , bifunctors    >= 3.0
                    , lens          >= 4.0 && < 5
                    , transformers  >= 0.3 && < 0.5

  ghc-options:
                    -Wall

  default-extensions:
                    NoImplicitPrelude

  hs-source-dirs:
                    src

  exposed-modules:
                    Data.Validation

test-suite doctests
  type:
                    exitcode-stdio-1.0

  main-is:
                    doctests.hs

  default-language:
                    Haskell2010

  build-depends:
                      base < 5 && >= 3
                    , doctest >= 0.9.7
                    , filepath >= 1.3
                    , directory >= 1.1
                    , QuickCheck >= 2.0
                    , template-haskell >= 2.8

  ghc-options:
                    -Wall
                    -threaded

  hs-source-dirs:
                    test