Hi, 2011/2/10 Yitzchak Gale <[email protected]>
> Simon Peyton-Jones wrote: > > "Generic Defaults"... will replace... the "Derivable type classes" > > stuff... in GHC 7.2 or 7.4... > > Please yell if you are a secret user of derivable type classes, > > so this change would discombobulate you. > > Could you give us a preview of the parts of the syntax > spectrum that will be gobbled up by this? That is a way > that the change could affect even people who are not using > the current generics. > As far as I understand, only the keyword "generic" will be taken. A new GHC.Generics module will define many new types with common names like `C` and `D`; these are used for the generic representation of datatypes in any module that enables -XGenerics, but there are no clashes unless the programmer explicitly imports GHC.Generics, so that should be ok. > > For example, the old generics knocked a very nice bracket > out of consideration for TH syntax. It also blessed the names > of certain magical constructors, which can be good to know > about even if the magic doesn't leak out of the generics world. > I remember there was some strange behavior with a type constructor `1` which was supposedly caused by the old generics (or was it syb?). Hopefully there will be nothing like that in the new mechanism. Cheers, Pedro > > Thanks, > Yitz >
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