indextype 0.1.0.0 → 0.2.0.0

raw patch · 4 files changed

+72/−9 lines, 4 filesdep ~basedep ~hspec

Dependency ranges changed: base, hspec

Files

• indextype.cabal +7/−7
• src/Control/IndexT.hs +0/−1
• src/Control/IndexT/Constructor.hs +64/−0
• src/Control/IndexT/Tuple.hs +1/−1

@@ -1,5 +1,5 @@ name:                 indextype-version:              0.1.0.0+version:              0.2.0.0 synopsis: A series of type families and constraints for "indexable" types. description:   This package deals with types that can roughly be "indexed" at compile time by an integer.@@ -7,7 +7,7 @@   A number of type functions allow one to extract these subtypes, i.e. the type of the 2nd element of a given tuple.    Furthermore, constraints are defined which allow one to easily constrain types to these index types,-  e.g. a constraint that says "@t@ is a 3 tuple". @Control.IndexT@ has more detail.+  e.g. a constraint that says "'t' is a 3 tuple". 'Control.IndexT' has more detail. author:               Clinton Mead maintainer:           clintonmead@gmail.com category:             Control@@ -17,22 +17,22 @@ build-type:           Simple cabal-version:        >=1.10 tested-with: GHC == 8.0.2-bug-reports:+bug-reports: https://github.com/clintonmead/indextype/issues  source-repository head   type: git   location: https://github.com/clintonmead/indextype.git  library-  exposed-modules:      Control.IndexT, Control.IndexT.Tuple, Control.IndexT.Function-  build-depends:        base >= 4.7 && < 5+  exposed-modules:      Control.IndexT, Control.IndexT.Tuple, Control.IndexT.Function, Control.IndexT.Constructor+  build-depends:        base == 4.9.*   hs-source-dirs:       src   default-language:     Haskell2010  Test-Suite tests   type: exitcode-stdio-1.0   main-is: Tests.hs-  other-modules: Control.IndexT, Control.IndexT.Tuple, Control.IndexT.Function-  build-depends:        base >= 4.7 && < 5, hspec+  other-modules: Control.IndexT, Control.IndexT.Tuple, Control.IndexT.Function, Control.IndexT.Constructor+  build-depends:        base == 4.9.*, hspec == 2.4.*   hs-source-dirs:       test, src   default-language:     Haskell2010

@@ -42,7 +42,6 @@   ) where  import GHC.TypeLits (Nat)-import GHC.Exts (Constraint) import Data.Functor.Identity (Identity)  {-|

@@ -0,0 +1,64 @@+{-# LANGUAGE TypeFamilies #-}+{-# LANGUAGE DataKinds #-}+{-# LANGUAGE KindSignatures #-}+{-# LANGUAGE ConstraintKinds #-}+{-# LANGUAGE UndecidableInstances #-}++{-|+This module provides a way to constrain types to be data constructors, much like+"Control.IndexT.Tuple" and "Control.IndexT.Function".++It also provides type families for accessing the elements of those data constructors,+both the constructors themselves and the parameters to them.++Note I haven't yet wrote code to generate many instances for these, so currently only+constructors with up to two parameters is supported. Just nag me if your application+needs more.+-}+module Control.IndexT.Constructor (+  IndexC,+  -- $getConstructorDocs+  GetConstructor1,+  GetConstructor2,+  IsData+)+where++import GHC.TypeLits (Nat)+import GHC.Exts (Constraint)++{-|+> IndexC i n (f a_0 a_1 .. a_(n-1))++the ith (zero based) parameter of the constructor with n parameters, i.e. @a_i@+-}+type family IndexC (n :: Nat) (i :: Nat) a++type instance IndexC 1 0 (_ a) = a+type instance IndexC 2 0 (_ a _) = a+type instance IndexC 2 1 (_ _ a) = a++{- $getConstructorDocs+These functions actually get the constructor, Unfortunately these are separate named functions instead+of being indexed by @n@ because they have different kinds, i.e. 'GetConstructor1' is @* -> *@+whereas 'GetConstructor2' is @* -> * -> *@. If there's a better way of doing this let me know.+-}+type family GetConstructor1 a where+  GetConstructor1 (f _) = f++type family GetConstructor2 a where+  GetConstructor2 (f _ _) = f++type Data1 a = (GetConstructor1 a) (IndexC 1 0 a)+type IsData1 a = (a ~ Data1 a)++type Data2 a = (GetConstructor2 a) (IndexC 2 0 a) (IndexC 2 1 a)+type IsData2 a = (a ~ Data2 a)++{-|+Much like 'Control.IndexT.Tuple.IsTuple' and 'Control.IndexT.Function.IsFunction', @IsData m t@ asserts that+@t@ is a data constructor with @n@ variables.+-}+type family IsData (n :: Nat) a :: Constraint+type instance IsData 1 a = IsData1 a+type instance IsData 2 a = IsData2 a

@@ -80,7 +80,7 @@  So @HomoTupleConstraint 3 t@ basically says @t ~ (u,u,u)@ for some @u@, -("Homo" is short for "Homogeneous". Like milk.)+(\"Homo\" is short for \"Homogeneous\". As in, all the same. Or like milk.) -} type family HomoTupleConstraint (n :: Nat) a :: Constraint type instance HomoTupleConstraint 0 a = (TupleConstraint 0 a)