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
  24  = Type_Type2 (Proxy (->))
  25
  26 type instance Constraint2_of (Proxy (->))
  27  = Constraint2_Empty
  28 instance Unlift_Type1 (Type_Type2 (Proxy (->))) where
  29         unlift_type1 (Type_Type2 px a b) k =
  30                 k ( Type_Type1 (Proxy::Proxy ((->) a)) b
  31                   , Lift_Type1 (\(Type_Type1 _ b') -> Type_Type2 px a b')
  32                   )
  33 instance Eq_Type root => Eq_Type1 (Type_Type2 (Proxy (->)) root) where
  34         eq_type1 (Type_Type2 _ a1 _b1) (Type_Type2 _ a2 _b2)
  35          | Just Refl <- eq_type a1 a2
  36          = Just Refl
  37         eq_type1 _ _ = Nothing
  38 instance
  39  Constraint_Type Monoid root =>
  40  Constraint_Type Monoid (Type_Type2 (Proxy (->)) root) where
  41         constraint_type c (Type_Type2 _ _arg res)
  42          | Just Dict <- constraint_type c res
  43          = Just Dict
  44         constraint_type _c _ = Nothing
  45 instance (Constraint_Type1 Functor root)
  46  => Constraint_Type1 Functor (Type_Type2 (Proxy (->)) root) where
  47         constraint_type1 _c Type_Type2{} = Just Dict
  48 instance (Constraint_Type1 Applicative root)
  49  => Constraint_Type1 Applicative (Type_Type2 (Proxy (->)) root) where
  50         constraint_type1 _c Type_Type2{} = Just Dict
  51 instance Constraint_Type1 Foldable (Type_Fun root)
  52 instance Constraint_Type1 Traversable (Type_Fun root)
  53 instance Constraint_Type1 Monad (Type_Fun root) where
  54         constraint_type1 _c Type_Type2{} = Just Dict
  55
  56 pattern Type_Fun
  57  :: root arg -> root res
  58  -> Type_Fun root ((->) arg res)
  59 pattern Type_Fun arg res
  60  = Type_Type2 Proxy arg res
  61
  62 instance -- Eq_Type
  63  Eq_Type root =>
  64  Eq_Type (Type_Type2 (Proxy (->)) root) where
  65         eq_type
  66          (Type_Type2 _ arg1 res1)
  67          (Type_Type2 _ arg2 res2)
  68          | Just Refl <- arg1 `eq_type` arg2
  69          , Just Refl <- res1 `eq_type` res2
  70          = Just Refl
  71         eq_type _ _ = Nothing
  72 instance -- String_from_Type
  73  String_from_Type root =>
  74  String_from_Type (Type_Fun root) where
  75         string_from_type (Type_Type2 _ arg res) =
  76                 "(" ++ string_from_type arg ++ " -> "
  77                     ++ string_from_type res ++ ")"
  78
  79 -- | Convenient alias to include a 'Type_Fun' within a type.
  80 type_fun
  81  :: forall root h_arg h_res.
  82  Lift_Type_Root Type_Fun root
  83  => root h_arg -> root h_res
  84  -> root ((->) h_arg h_res)
  85 type_fun arg res = lift_type_root (Type_Fun arg res
  86          ::Type_Fun root ((->) h_arg h_res))
  87
  88 -- | Parse 'Type_Fun'.
  89 type_fun_from
  90  :: forall (root :: * -> *) ast ret.
  91  ( Lift_Type_Root Type_Fun root
  92  , Type_from ast root
  93  , Root_of_Type root ~ root
  94  ) => Proxy (Type_Fun root)
  95  -> ast -> ast
  96  -> (forall h. root h -> Either (Error_of_Type ast root) ret)
  97  -> Either (Error_of_Type ast root) ret
  98 type_fun_from _ty ast_arg ast_res k =
  99         type_from (Proxy::Proxy root) ast_arg $ \(ty_arg::root h_arg) ->
 100         type_from (Proxy::Proxy root) ast_res $ \(ty_res::root h_res) ->
 101         k (ty_arg `type_fun` ty_res
 102          :: root ((->) h_arg h_res))