#10796: Illegal data constructor name: `fromList' ... When splicing a TH expression -------------------------------------+------------------------------------- Reporter: erisco | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.8.3 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): -------------------------------------+------------------------------------- Comment (by RyanGlScott): One thing isn't clear to me about the changes proposed. We could certainly modify `dataToQa` so that `dataToExpQ` (and thus `liftData`) works with both function and constructor names. What about `dataToPatQ`, though? There's no way to pattern-match on an expression directly, so what would this translate to? {{{#!hs f :: Set Char -> Set Char f s@($(dataToPatQ (const Nothing) (fromList "test"))) = s }}} The only way I could envision this working is if it were translated to something like: {{{#!hs f :: Set Char -> Set Char f x | x == fromList "test" = x }}} which is reminiscent of how pattern-matching on literals works, I suppose. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10796#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler