#7647: UNPACK polymorphic fields ------------------------------------+--------------------------------------- Reporter: liyang | Owner: simonpj Type: feature request | Status: new Priority: normal | Component: Compiler Version: 7.6.1 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: Runtime performance bug | Blockedby: Blocking: | Related: 3990 ------------------------------------+--------------------------------------- comment:9:ticket:3990 mentions the possibility of unpacking polymorphic fields. To quote: […] What I mean by "polymorphic unpack" is this: {{{ data Poly a = MkP Bool {-# UNPACK #-} a data Mango = MkMango {-# UNPACK #-} (Poly Int) }}} Now a value of type Poly t would be represented using two pointer fields, as usual (ie the UNPACK would have no direct effect on Poly). But a Mango value would be represented thus: {{{ data Mango = MkMangoRep Bool Int# MkMango :: Poly Int -> MangoRep MkMango (MkP b (I# i)) = MkMangoRep b i -- Pattern match (MkMango p -> rhs) -- is transformed to (MkMangoRep b i -> let p = MkP b (I# i) in rhs }}} Something like that would be rather nice. This ticket is just a reminder. Thanks,[[br]] /Liyang -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7647 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler