add gEq,JSON instance for MaybeError

src/libraries/OS-Independent/Data/Error.dcl

@@ -4,6 +4,7 @@ from Data.Functor import class Functor
 from Control.Monad import class Monad
 from Control.Applicative import class Applicative
 from Data.Maybe import :: Maybe
+from Data.GenEq import generic gEq
 
 /**
  * A type representing something that may have failed.
@@ -22,6 +23,8 @@ instance Functor (MaybeError a)
 instance Applicative (MaybeError a)
 instance Monad (MaybeError a)
 
+derive gEq MaybeError
+
 /**
  * Return True when the argument is an Ok value and return False otherwise.
  */

src/libraries/OS-Independent/Data/Error.icl

 implementation module Data.Error
 
 import StdMisc
-import Data.Functor, Data.Maybe
+import Data.Functor, Data.Maybe, Data.GenEq
 import Control.Monad
 import Control.Applicative
 	
@@ -19,6 +19,8 @@ instance Monad (MaybeError e) where
     bind (Error l) _ = Error l
     bind (Ok r) k = k r
 
+derive gEq MaybeError
+
 isOk		:: !(MaybeError a b) -> Bool
 isOk		(Ok _) 		= True
 isOk		(Error _)	= False

src/libraries/OS-Independent/Data/Error/GenJSON.dcl

+definition module Data.Error.GenJSON
+
+from Data.Error   import :: MaybeError
+from Text.GenJSON import generic JSONEncode, generic JSONDecode, :: JSONNode
+from Data.Maybe   import :: Maybe
+
+derive JSONEncode MaybeError
+derive JSONDecode MaybeError

src/libraries/OS-Independent/Data/Error/GenJSON.icl

+implementation module Data.Error.GenJSON
+
+import Data.Error, Text.GenJSON
+
+derive JSONEncode MaybeError
+derive JSONDecode MaybeError