Language/Symantic/Type/Fun.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE GADTs #-}
   4 {-# LANGUAGE MultiParamTypeClasses #-}
   5 {-# LANGUAGE OverloadedStrings #-}
   6 {-# LANGUAGE PatternSynonyms #-}
   7 {-# LANGUAGE Rank2Types #-}
   8 {-# LANGUAGE ScopedTypeVariables #-}
   9 {-# LANGUAGE TypeFamilies #-}
  10 {-# OPTIONS_GHC -fno-warn-orphans #-}
  11 module Language.Symantic.Type.Fun where
  12
  13 import Data.Proxy
  14 import Data.Type.Equality ((:~:)(Refl))
  15 import Language.Symantic.Type.Root
  16 import Language.Symantic.Type.Error
  17 import Language.Symantic.Type.Type0
  18 import Language.Symantic.Type.Type1
  19 import Language.Symantic.Type.Type2
  20
  21 -- * Type 'Type_Fun'
  22 -- | The @->@ type.
  23 type Type_Fun = Type_Type2 (Proxy (->))
  24
  25 instance Unlift_Type1 Type_Fun where
  26         unlift_type1 (Type_Type2 px a b) k =
  27                 k ( Type_Type1 (Proxy::Proxy ((->) a)) b
  28                   , Lift_Type1 (\(Type_Type1 _ b') -> Type_Type2 px a b')
  29                   )
  30 instance Eq_Type root => Eq_Type1 (Type_Fun root) where
  31         eq_type1 (Type_Type2 _ a1 _b1) (Type_Type2 _ a2 _b2)
  32          | Just Refl <- eq_type a1 a2
  33          = Just Refl
  34         eq_type1 _ _ = Nothing
  35 instance Constraint_Type Eq (Type_Fun root) where
  36         constraint_type _c _ = Nothing
  37 instance Constraint_Type Ord (Type_Fun root) where
  38         constraint_type _c _ = Nothing
  39 instance
  40  Constraint_Type Monoid root =>
  41  Constraint_Type Monoid (Type_Fun root) where
  42         constraint_type c (Type_Type2 _ _arg res)
  43          | Just Dict <- constraint_type c res
  44          = Just Dict
  45         constraint_type _c _ = Nothing
  46 instance Constraint_Type1 Functor (Type_Fun root) where
  47         constraint_type1 _c Type_Type2{} = Just Dict
  48 instance Constraint_Type1 Applicative (Type_Fun root) where
  49         constraint_type1 _c Type_Type2{} = Just Dict
  50 instance Constraint_Type1 Foldable (Type_Fun root)
  51 instance Constraint_Type1 Traversable (Type_Fun root)
  52 instance Constraint_Type1 Monad (Type_Fun root) where
  53         constraint_type1 _c Type_Type2{} = Just Dict
  54
  55 pattern Type_Fun
  56  :: root arg -> root res
  57  -> Type_Fun root ((->) arg res)
  58 pattern Type_Fun arg res
  59  = Type_Type2 Proxy arg res
  60
  61 instance -- Eq_Type
  62  Eq_Type root =>
  63  Eq_Type (Type_Fun root) where
  64         eq_type
  65          (Type_Type2 _ arg1 res1)
  66          (Type_Type2 _ arg2 res2)
  67          | Just Refl <- arg1 `eq_type` arg2
  68          , Just Refl <- res1 `eq_type` res2
  69          = Just Refl
  70         eq_type _ _ = Nothing
  71 instance -- String_from_Type
  72  String_from_Type root =>
  73  String_from_Type (Type_Fun root) where
  74         string_from_type (Type_Type2 _ arg res) =
  75                 "(" ++ string_from_type arg ++ " -> "
  76                     ++ string_from_type res ++ ")"
  77
  78 -- | Convenient alias to include a 'Type_Fun' within a type.
  79 type_fun
  80  :: forall root h_arg h_res.
  81  Lift_Type_Root Type_Fun root
  82  => root h_arg -> root h_res
  83  -> root ((->) h_arg h_res)
  84 type_fun arg res = lift_type_root (Type_Fun arg res
  85          ::Type_Fun root ((->) h_arg h_res))
  86
  87 -- | Parse 'Type_Fun'.
  88 type_fun_from
  89  :: forall (root :: * -> *) ast ret.
  90  ( Lift_Type_Root Type_Fun root
  91  , Type_from ast root
  92  , Root_of_Type root ~ root
  93  ) => Proxy (Type_Fun root)
  94  -> ast -> ast
  95  -> (forall h. root h -> Either (Error_of_Type ast root) ret)
  96  -> Either (Error_of_Type ast root) ret
  97 type_fun_from _ty ast_arg ast_res k =
  98         type_from (Proxy::Proxy root) ast_arg $ \(ty_arg::root h_arg) ->
  99         type_from (Proxy::Proxy root) ast_res $ \(ty_res::root h_res) ->
 100         k (ty_arg `type_fun` ty_res
 101          :: root ((->) h_arg h_res))