Language/Symantic/Type/Maybe.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE TypeFamilies #-}
   4 {-# OPTIONS_GHC -fno-warn-orphans #-}
   5 module Language.Symantic.Type.Maybe where
   6
   7 import Data.Proxy
   8
   9 import Language.Symantic.Type.Common
  10
  11 -- * Type 'Type_Maybe'
  12 -- | The 'Maybe' type.
  13 type Type_Maybe = Type_Type1 Maybe
  14
  15 instance -- String_from_Type
  16  String_from_Type root =>
  17  String_from_Type (Type_Maybe root) where
  18         string_from_type (Type_Type1 _f a) =
  19                 "Maybe" ++ " (" ++ string_from_type a ++ ")"
  20
  21 -- | Inject a 'Type_Maybe' within a root type.
  22 type_maybe
  23  :: Lift_Type_Root Type_Maybe root
  24  => root h_a
  25  -> root (Maybe h_a)
  26 type_maybe = lift_type_root . Type_Type1 (Proxy::Proxy Maybe)