It's harmless. But it's there to tell us that a RULE is not going to match because the LHS involves a coercion that is not Refl or a variable. Matching on more complex coercions is likely to be fragile, since they can take a variety of forms.
So don't worry too much, but I'd be interested in a repro case Simon | -----Original Message----- | From: glasgow-haskell-users-boun...@haskell.org [mailto:glasgow-haskell- | users-boun...@haskell.org] On Behalf Of Evan Laforge | Sent: 27 May 2013 18:56 | To: GHC users | Subject: match_co: needs more cases | | I made some strictifying changes and started getting this msg from ghc: | | match_co: needs more cases | vector-0.10.0.1:Data.Vector.Generic.Mutable.MVector{tc r46} | (Sym <(vector-0.10.0.1:Data.Vector.TFCo:R:MutableVector{tc r45})>) | <main:Util.TimeVectorStorable.Sample{tc r4e} y{tv a4lK} [tv]> | | It's not just TimeVectorStorable.Sample (which is indeed stored in | Data.Vectors), we also have some mysterious compiler-generated | symbols: | | match_co: needs more cases | vector-0.10.0.1:Data.Vector.Generic.Mutable.MVector{tc rQA} | (Sym <(vector-0.10.0.1:Data.Vector.TFCo:R:MutableVector{tc rQz})>) | <a{tv a6IH} [tv]> | | I assume this is harmless, but I didn't see any other references to | this error on the web or on the ghc trac so maybe it's new? | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
