name: discrete version: 0.1.0.0 synopsis: replacement for enum description: A 'Discrete' type is a set X with at least one element, along with two functions, @'succ' :: X -> 'Maybe' X@ and @'pred' :: X -> 'Maybe' X@, such that all inhabitants of the set X can be constructed given at least a single element of the set and these two functions. The following must hold: @'pred' '>=>' 'succ' '>=>' 'pred' = 'pred'@ @'succ' '>=>' 'pred' '>=>' 'succ' = 'succ'@ This means that 'Int' is a discrete type, because given any x :: 'Int', one can construct any other 'Int' with the following functions: @'succ' x = if x '==' 'maxBound' then 'Nothing' else 'Just' (x '+' 1)@ @'pred' x = if x '==' 'minBound' then 'Nothing' else 'Just' (x '-' 1)@ This also means that something like 'Double' is /not/ a discrete type, because there are no such functions 'succ' and 'pred' that given any value of type 'Double' can allow the construction of all values of type 'Double'. 'Discrete' acts as a replacement for 'GHC.Enum.Enum'. The motivation for 'Discrete' is two-fold: firstly, totality of all typeclass instances, and secondly, that 'GHC.Enum.Enum' is a typeclass that does too many things, and does them poorly. If 'succ' or 'pred' are called on 'maxBound' or 'minBound', respectively, the result will be 'Nothing'. homepage: https://github.com/chessai/discrete license: BSD3 license-file: LICENSE author: chessai maintainer: chessai1996@gmail.com category: Data build-type: Simple extra-source-files: ChangeLog.md cabal-version: >=1.10 library exposed-modules: Data.Discrete Data.Modular build-depends: base >=4.7 && <4.13 default-language: Haskell2010