Language/Symantic/Type/Ordering.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE GADTs #-}
   3 {-# LANGUAGE MultiParamTypeClasses #-}
   4 {-# LANGUAGE OverloadedStrings #-}
   5 {-# LANGUAGE ScopedTypeVariables #-}
   6 {-# LANGUAGE TypeFamilies #-}
   7 module Language.Symantic.Type.Ordering where
   8
   9 import Data.Maybe (isJust)
  10 import Data.Type.Equality ((:~:)(Refl))
  11
  12 import Language.Symantic.Type.Common
  13
  14 -- * Type 'Type_Ordering'
  15 -- | The 'Ordering' type.
  16 data Type_Ordering (root:: * -> *) h where
  17         Type_Ordering :: Type_Ordering root Ordering
  18 type instance Root_of_Type      (Type_Ordering root) = root
  19 type instance Error_of_Type ast (Type_Ordering root) = ()
  20
  21 instance -- Type_Eq
  22  Type_Eq (Type_Ordering root) where
  23         type_eq Type_Ordering Type_Ordering = Just Refl
  24 instance -- Eq
  25  Eq (Type_Ordering root h) where
  26         x == y = isJust $ x `type_eq` y
  27 instance -- String_from_Type
  28  String_from_Type (Type_Ordering root) where
  29         string_from_type Type_Ordering = "Ordering"
  30 instance -- Show
  31  Show (Type_Ordering root h) where
  32         show = string_from_type
  33
  34 -- | Convenient alias to include a 'Type_Ordering' within a type.
  35 type_ordering :: Type_Root_Lift Type_Ordering root => root Ordering
  36 type_ordering = type_root_lift Type_Ordering