#3990: UNPACK doesn't unbox data families --------------------------------------------+------------------------------ Reporter: rl | Owner: Type: bug | Status: new Priority: low | Milestone: 7.6.2 Component: Compiler | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by sjoerd_visscher): What about closed data families? GHC could check that every instance is unpackable. Then this would work: {{{ data Nat = Z | S Nat data family Vec (size :: Nat) where Vec Z = Nil Vec (S n) = Cons {-# UNPACK #-} !Double {-# UNPACK #-} !(Vec n) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/3990#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler