GitLab

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.

: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)

}}}

Trac metadata

Trac field	Value
Version	7.8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Template Haskell
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Windows
Architecture	x86_64 (amd64)