Language/LOL/Symantic/Type/Bool.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE GADTs #-}
   3 {-# LANGUAGE MultiParamTypeClasses #-}
   4 {-# LANGUAGE OverloadedStrings #-}
   5 {-# LANGUAGE ScopedTypeVariables #-}
   6 {-# LANGUAGE TypeFamilies #-}
   7 {-# LANGUAGE UndecidableInstances #-}
   8 module Language.LOL.Symantic.Type.Bool where
   9
  10 import Data.Maybe (isJust)
  11 import Data.Type.Equality ((:~:)(Refl))
  12
  13 import Language.LOL.Symantic.AST
  14 import Language.LOL.Symantic.Type.Common
  15 import Language.LOL.Symantic.Type.Fun
  16
  17 -- * Type 'Type_Bool'
  18
  19 -- | The 'Bool' type.
  20 data Type_Bool (root:: * -> *) h where
  21         Type_Bool :: Type_Bool root Bool
  22 type instance Root_of_Type (Type_Bool root) = root
  23 type instance Error_of_Type ast (Type_Bool root) = Error_Type_Fun ast
  24
  25 instance -- Type_Eq
  26  Type_Eq (Type_Bool root) where
  27         type_eq Type_Bool Type_Bool = Just Refl
  28 instance -- Eq
  29  Eq (Type_Bool root h) where
  30         x == y = isJust $ type_eq x y
  31 instance -- Type_from AST
  32  ( Type_Root_Lift Type_Bool root
  33  , Error_Type_Lift (Error_Type AST) (Error_of_Type AST root)
  34    -- NOTE: require UndecidableInstances.
  35  , Error_Type_Lift (Error_Type_Fun AST) (Error_of_Type AST root)
  36    -- NOTE: require UndecidableInstances.
  37  , Implicit_HBool (Is_Last_Type (Type_Bool root) root)
  38  ) => Type_from AST (Type_Bool root) where
  39         type_from _px_ty ast k =
  40                 case ast of
  41                  AST "Bool" asts ->
  42                         case asts of
  43                          [] -> k $ type_root_lift Type_Bool
  44                          _ -> Left $ error_type_lift $
  45                                 Error_Type_Fun_Wrong_number_of_arguments 0 ast
  46                  _ -> Left $
  47                         case hbool :: HBool (Is_Last_Type (Type_Bool root) root) of
  48                          HTrue  -> error_type_lift $ Error_Type_Unsupported ast
  49                          HFalse -> error_type_lift $ Error_Type_Unsupported_here ast
  50 instance -- String_from_Type
  51  String_from_Type (Type_Bool root) where
  52         string_from_type Type_Bool = "Bool"
  53 instance -- Show
  54  Show (Type_Bool root h) where
  55         show = string_from_type
  56
  57 -- | Convenient alias to include a 'Type_Bool' within a type.
  58 type_bool :: Type_Root_Lift Type_Bool root => root Bool
  59 type_bool = type_root_lift Type_Bool
  60
  61 -- * Type 'Type_Fun_Bool'
  62 -- | Convenient alias.
  63 type Type_Fun_Bool lam = Type_Root (Type_Alt (Type_Fun lam) Type_Bool)