Hi, the GHC 7.8.2 installation on my machine refuses to import GHC.Prim if Safe is enabled. The locally generated documentation still claims that GHC.Prim is Safe-Inferred, though. So this seems to be indeed a documentation bug.
All the best, Wolfgang Am Sonntag, den 17.08.2014, 11:26 -0400 schrieb Richard Eisenberg: > Have you tried doing this? If so, `coerce` is the least of our > problems: `unsafeCoerce#` is much worse! When I just tried, GHC told > me that I couldn't import GHC.Prim into a module with -XSafe enabled. > > So, this seems to be a documentation bug (the Haddock description of > GHC.Prim indeed says "Safe Inferred"), but not a "real" bug. > > Let me know if you see otherwise! > > Thanks, > Richard > > On Aug 16, 2014, at 6:06 PM, Wolfgang Jeltsch <g9ks1...@acme.softbase.org> > wrote: > > > Hi, > > > > thank you for these links. > > > > Still, it is interesting that also in GHC 7.8 you can have a coerce that > > is considered “Safe”, although the discussions on Trac concluded that > > this should not be the case. You can just import coerce via GHC.Prim, > > which is “Safe-Inferred”. > > > > All the best, > > Wolfgang > > > > Am Freitag, den 15.08.2014, 19:40 -0400 schrieb Richard Eisenberg: > >> See https://ghc.haskell.org/trac/ghc/ticket/8745 and > >> https://ghc.haskell.org/trac/ghc/ticket/8827 which discuss this problem at > >> length. > >> > >> The short answer: It's conceivable that a role-unaware library author > >> would have abstraction expectations that are defeated through the use of > >> `coerce`. > >> > >> I would strongly welcome a proposal for how to make `coerce`, and hence > >> GeneralizedNewtypeDeriving, to be considered Safe for 7.10. > >> > >> Richard > >> > >> On Aug 15, 2014, at 4:04 PM, Wolfgang Jeltsch <g9ks1...@acme.softbase.org> > >> wrote: > >> > >>> Hi, > >>> > >>> I would expect the function > >>> > >>> coerce :: Coercible a b => a -> b > >>> > >>> to be safe in the sense of Safe Haskell. However, the Data.Coerce module > >>> is marked “Unsafe”. The coerce function is also available via GHC.Exts > >>> and GHC.Prim. The former module is marked “Unsafe”, but the latter is > >>> (surprisingly) marked “Safe-Inferred”. > >>> > >>> What are the reasons behind this? > >>> > >>> All the best, > >>> Wolfgang > >>> > >>> _______________________________________________ > >>> 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 > > > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
