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
