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 import Language.LOL.Symantic.Type.Var
  17
  18 -- * Type 'Type_Bool'
  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) = ()
  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 $ x `type_eq` 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  , Implicit_HBool (Is_Last_Type (Type_Bool root) root)
  35  ) => Type_from AST (Type_Bool root) where
  36         type_from px_ty ast k =
  37                 case ast of
  38                  AST "Bool" asts ->
  39                         case asts of
  40                          [] -> k $ type_root_lift Type_Bool
  41                          _ -> Left $ error_type_lift $
  42                                 Error_Type_Wrong_number_of_arguments ast 0
  43                  _ -> Left $ error_type_unsupported px_ty ast
  44 instance -- String_from_Type
  45  String_from_Type (Type_Bool root) where
  46         string_from_type Type_Bool = "Bool"
  47 instance -- Show
  48  Show (Type_Bool root h) where
  49         show = string_from_type
  50
  51 -- | Convenient alias to include a 'Type_Bool' within a type.
  52 type_bool :: Type_Root_Lift Type_Bool root => root Bool
  53 type_bool = type_root_lift Type_Bool
  54
  55 -- * Type 'Type_Fun_Bool'
  56 -- | Convenient alias.
  57 type Type_Fun_Bool lam
  58  = Type_Root (Type_Alt  Type_Var
  59              (Type_Alt (Type_Fun lam)
  60                         Type_Bool))