type-level-sets-0.8.9.0: type-level-sets.cabal

name:                   type-level-sets
version:                0.8.9.0
synopsis:               Type-level sets and finite maps (with value-level counterparts)
description:
   This package provides type-level sets (no duplicates, sorted to provide a normal form) via 'Set' and type-level
   finite maps via 'Map', with value-level counterparts.
   .
   Described in the paper \"Embedding effect systems in Haskell\" by Dominic Orchard
   and Tomas Petricek <http://www.cl.cam.ac.uk/~dao29/publ/haskell14-effects.pdf> (Haskell Symposium, 2014). This version now uses Quicksort to normalise the representation.
   .
   Here is a brief example for finite maps:
   .
   >
   > import Data.Type.Map
   >
   > -- Specify how to combine duplicate key-value pairs for Int values
   > type instance Combine Int Int = Int
   > instance Combinable Int Int where
   >     combine x y = x + y
   >
   > foo :: Map '["x" :-> Int, "z" :-> Bool, "w" :-> Int]
   > foo = Ext (Var :: (Var "x")) 2
   >     $ Ext (Var :: (Var "z")) True
   >     $ Ext (Var :: (Var "w")) 5
   >     $ Empty
   >
   > bar :: Map '["y" :-> Int, "w" :-> Int]
   > bar = Ext (Var :: (Var "y")) 3
   >     $ Ext (Var :: (Var "w")) 1
   >     $ Empty
   >
   > -- foobar :: Map '["w" :-> Int, "x" :-> Int, "y" :-> Int, "z" :-> Bool]
   > foobar = foo `union` bar
   .
   The 'Map' type for 'foobar' here shows the normalised form (sorted with no duplicates).
   The type signatures is commented out as it can be infered. Running the example we get:
   .
   > >>> foobar
   > {w :-> 6, x :-> 2, y :-> 3, z :-> True}
   .
   Thus, we see that the values for \"w\" are added together.
   For sets, here is an example:
   .
   > import GHC.TypeLits
   > import Data.Type.Set
   > type instance Cmp (Natural n) (Natural m) = CmpNat n m
   >
   > data Natural (a :: Nat) where
   >   Z :: Natural 0
   >   S :: Natural n -> Natural (n + 1)
   >
   > -- foo :: Set '[Natural 0, Natural 1, Natural 3]
   > foo = asSet $ Ext (S Z) (Ext (S (S (S Z))) (Ext Z Empty))
   >
   > -- bar :: Set '[Natural 1, Natural 2]
   > bar = asSet $ Ext (S (S Z)) (Ext (S Z) (Ext (S Z) Empty))
   >
   > -- foobar :: Set '[Natural 0, Natural 1, Natural 2, Natural 3]
   > foobar = foo `union` bar
   .
   Note the types here are all inferred.
   .
license:                BSD3
license-file:           LICENSE
category:               Type System, Data Structures
copyright:              2013-18 University of Kent
author:                 Dominic Orchard
maintainer:             Dominic Orchard
stability:              experimental
build-type:             Simple
cabal-version:          >= 1.6
tested-with:            GHC >= 8.2.2

extra-source-files:     example.hs, example2.hs


source-repository head
  type: git
  location: https://github.com/dorchard/type-level-sets

library
  hs-source-dirs:       src


  exposed-modules:      Data.Type.Set
                        Data.Type.Map

  build-depends:        base < 5,
                        ghc-prim