So in the mean time , if I want write a data type that's polymorphic over types that are heap pointer represented, I'll need to use a kind type class to bound my polymorphism? I'm interested in trying To understand if this lets me quantify over ptry structures safely.
@ed, does any of this have an impact or relevance to your structs lib experiment you were sharing at Icfp? On Tuesday, April 5, 2016, Richard Eisenberg <[email protected]> wrote: > Yes, that's correct. The RuntimeRep story generally allows for such > polymorphism in the future, but it's not implemented yet. One concern is > that doing this would require RuntimeRep to look like > > data Levity = Lifted | Unlifted > data RuntimeRep = PtrRep Levity | IntRep | VoidRep | ... > > > The problem here is that, in the vastly common case of kind *, this > requires an extra indirection. I actually implemented this, and indeed the > performance of GHC decreased. Given that we have no way, yet, to take > advantage of the kind of polymorphism you seek, I flattened the structure > of RuntimeRep in order to get a modest but consistent performance boost. > > So I'm, personally, very open to this direction of travel, but we have to > work out both how the polymorphism should work and how to implement this > without degrading performance. > > Richard > > On Apr 5, 2016, at 2:54 AM, Carter Schonwald <[email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: > > i was reading https://ghc.haskell.org/trac/ghc/wiki/NoSubKinds > and looking at some of the applicable code, and it looks like i can't > quantify over ptr-y heap values that may or may not be lifted, at least > with the current state of play, is this correct? > _______________________________________________ > ghc-devs mailing list > [email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');> > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > > >
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