Hi all,
The Q Monad in template haskell has fail method. As I understand it, it
throws some kind of exception. How do I catch this exception?
Some code I'm trying to create:
infoToCode :: Info -> Q Exp
infoToCode (ClassI dec) = -- ClassI Dec
fail "ClassI not supported" -- this will be implemented
infoToCode (ClassOpI name xtype name2 fixity) = -- ClassOpI Name Type
Name Fixity
fail "ClassOpI not supported"
infoToCode (TyConI dec) = -- TyConI Dec
fail "TyConI not supported"
infoToCode (PrimTyConI name int bool) = -- PrimTyConI Name Int Bool
fail "PrimTyConI not supported"
infoToCode (DataConI name xtype name2 fixity) = -- DataConI Name Type
Name Fixity
fail "DataConI not supported"
infoToCode (VarI name xtype maybedec fixity) = -- VarI Name Type (Maybe
Dec) Fixity
fail "TVarI not supported"
infoToCode (TyVarI name xtype) = -- TyVarI Name Type
fail "TyVarI not supported"
nameToCode1 :: Name -> Q Exp
nameToCode1 name = do
info <- reify name
Code <- infoToCode info
runIO $ putStrLn $ pprint Code
return Code
-- Here be dragons...
nameToCode name = nameToCode1 name `catch` c
where c e = do
runIO $ putStrLn $ show e
fail "refailed"
--
Gracjan
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