Language/Symantic/Type/Tuple.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE GADTs #-}
   3 {-# LANGUAGE MultiParamTypeClasses #-}
   4 {-# LANGUAGE OverloadedStrings #-}
   5 {-# LANGUAGE ScopedTypeVariables #-}
   6 {-# LANGUAGE TypeFamilies #-}
   7 module Language.Symantic.Type.Tuple where
   8
   9 import Data.Maybe (isJust)
  10 import Data.Type.Equality ((:~:)(Refl))
  11
  12 import Language.Symantic.Type.Common
  13 import Language.Symantic.Type.Fun
  14 import Language.Symantic.Type.Bool
  15 import Language.Symantic.Type.Var
  16
  17 -- * Type 'Type_Tuple2'
  18 -- | The 'Tuple' type.
  19 data Type_Tuple2 root h where
  20         Type_Tuple2 :: root h_a
  21                     -> root h_b
  22                     -> Type_Tuple2 root (h_a, h_b)
  23
  24 type instance Root_of_Type      (Type_Tuple2 root) = root
  25 type instance Error_of_Type ast (Type_Tuple2 root) = No_Error_Type
  26
  27 instance -- Type_Eq
  28  Type_Eq root =>
  29  Type_Eq (Type_Tuple2 root) where
  30         type_eq (Type_Tuple2 a1 b1) (Type_Tuple2 a2 b2)
  31          | Just Refl <- a1 `type_eq` a2
  32          , Just Refl <- b1 `type_eq` b2
  33          = Just Refl
  34         type_eq _ _ = Nothing
  35 instance -- Eq
  36  Type_Eq root =>
  37  Eq (Type_Tuple2 root h) where
  38         x == y = isJust $ type_eq x y
  39 instance -- String_from_Type
  40  String_from_Type root =>
  41  String_from_Type (Type_Tuple2 root) where
  42         string_from_type (Type_Tuple2 a b) =
  43                 "Tuple (" ++ string_from_type a ++
  44                  ", " ++ string_from_type b ++ ")"
  45 instance -- Show
  46  String_from_Type root =>
  47  Show (Type_Tuple2 root h) where
  48         show = string_from_type
  49
  50 -- | Convenient alias to include a 'Type_Tuple2' within a type.
  51 type_tuple2
  52  :: Type_Root_Lift Type_Tuple2 root
  53  => root h_a
  54  -> root h_b
  55  -> root (h_a, h_b)
  56 type_tuple2 a b = type_root_lift (Type_Tuple2 a b)
  57
  58 -- * Type 'Type_Fun_Bool_Tuple2'
  59 -- | Convenient alias.
  60 type Type_Fun_Bool_Tuple2 lam
  61  = Type_Root (Type_Alt Type_Var
  62              (Type_Alt (Type_Fun lam)
  63              (Type_Alt Type_Bool
  64                        Type_Tuple2)))