#10796: Illegal data constructor name: `fromList' ... When splicing a TH expression -------------------------------------+------------------------------------- Reporter: erisco | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 7.8.3 Haskell | Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- At the end is a log of my ghci session reproducing the issue. It is expected that the splice should succeed, but GHC complains "Illegal data constructor name: `fromList' ... When splicing a TH expression". Full definitions being used can be found at http://hackage.haskell.org/package/regex-tdfa-quasiquoter-0.2.0.0 . Briefly, this is the splice being used. {{{#!hs [e|patternToRegex $patternExp $compOptsExp $execOptsExp|] where patternExp = dataToExpQ (const Nothing) pattern compOptsExp = dataToExpQ (const Nothing) compOpts execOptsExp = dataToExpQ (const Nothing) execOpts }}} Data and Typeable instances are derived (using -XStandaloneDeriving -XDeriveDataTypeable) as orphan instances in the Internal module. The issue occurs when using bracket expressions (in POSIX regular expressions). There may be other cases but I have not uncovered them. {{{
ghci GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done.
:set -XQuasiQuotes import Text.Regex.TDFA.QuasiQuoter :t [re|;[a]|] Loading package transformers-0.3.0.0 ... linking ... done. Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package bytestring-0.10.4.0 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. Loading package mtl-2.1.3.1 ... linking ... done. Loading package regex-base-0.93.2 ... linking ... done. Loading package text-1.2.0.3 ... linking ... done. Loading package parsec-3.1.9 ... linking ... done. Loading package regex-tdfa-1.2.0 ... linking ... done. Loading package pretty-1.1.1.1 ... linking ... done. Loading package template-haskell ... linking ... done. Loading package regex-tdfa-quasiquoter-0.2.0.0 ... linking ... done.
<interactive>:1:5: Illegal data constructor name: `fromList' When splicing a TH expression: Text.Regex.TDFA.TDFA.patternToRegex (GHC.Tuple.(,) (Text.Regex.TDFA.Pattern.POr ((GHC.Types.:) (Text.Regex.TDFA.Pattern.PConcat ((GHC.Types.:) (Text.Regex.TDFA.Pattern.PAny (Text.Regex.TDFA.Common.DoPa 1) (Text.Regex.TDFA.Pattern.PatternSet (Data.Maybe.Just (Data.Set.Base.fromList ((GHC.Types.:) 'a' GHC.Types.[]))) Data.Maybe.Nothing Data.Maybe.Nothing Data.Maybe.Nothing)) GHC.Types.[])) GHC.Types.[])) (GHC.Tuple.(,) 0 (Text.Regex.TDFA.Common.DoPa 1))) (Text.Regex.TDFA.Common.CompOption GHC.Types.True GHC.Types.True GHC.Types.True GHC.Types.True GHC.Types.False) (Text.Regex.TDFA.Common.ExecOption GHC.Types.True)
}}}
-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10796 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler