Dear Template Haskell folk This SourceForge bug is another example of the bad things that happen when: - a TH program constructs a syntactically invalid program - and then splices it in The trouble is that Convert.convertToHsExpr :: TH.Exp -> LHsExpr RdrName is a pure function, and fails "hard" with a panic, whereas it should really be in the TcM monad, and fail in the way any other type error fails. It's a user error, and should not show up as a panic. Would anyone like to fix hsSyn/Convert.lhs so that it lives in the Tc monad? The call (in TcSplice) is easily changed. It'd probably make sense to move it from hsSyn/ to typecheck/ I'm thinking about putting types in the syntax tree, so if others can help out with tidying up like this, it'd be great. Simon -----Original Message----- From: glasgow-haskell-bugs-bounces@haskell.org [mailto:glasgow-haskell-bugs-bounces@haskell.org] On Behalf Of SourceForge.net Sent: 16 July 2004 10:11 To: noreply@sourceforge.net Subject: [ ghc-Bugs-992200 ] Template crash on constructing existential datatype Bugs item #992200, was opened at 2004-07-16 09:11 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=108032&aid=992200&grou p_id=8032 Category: Compiler Group: 6.2.1 Status: Open Resolution: None Priority: 5 Submitted By: Mike Aizatsky (mm_aa) Assigned to: Nobody/Anonymous (nobody) Summary: Template crash on constructing existential data type Initial Comment: Windows XP D:\Tools\ghc>ghc-6.2.1\bin\ghc.exe -fglasgow-exts --make foo.hs Chasing modules from: foo.hs Compiling Any ( ./Any.hs, ./Any.o ) Compiling Foo ( foo.hs, foo.o ) Loading package base ... linking ... done. Loading package haskell98 ... linking ... done. Loading package haskell-src ... linking ... done. ghc.exe: panic! (the `impossible' happened, GHC version 6.2.1): Malformed predicate module Any where import Language.Haskell.THSyntax genAny :: DecQ -> Q [Dec] genAny decl = do{ d <- decl ; case d of ClassD _ name _ decls -> sequenceQ [genAnyClass (name) decls] _ -> error "genAny can be applied to classes only" } genAnyClass :: String -> [Dec] -> DecQ genAnyClass name decls = do{ returnQ (DataD [forall] anyName [] [constructor] []) } where anyName = "Any" ++ name ++ "1111" constructor = NormalC anyName [(NotStrict, VarT "a")] forall = ForallT [] [] (VarT "a") module Foo where import Any class MyInterface a where foo :: a -> Int foo1 :: Int -> a -> Int $(genAny (reifyDecl MyInterface)) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=108032&aid=992200&grou p_id=8032 _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs