#12364: Demand analysis for sum types -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Expanding demand analysis for sums will get info for {{{ f :: Maybe Int -> Int f Nothing = 3 f (Just x) = x + 1 }}} Currently if a call site looks like `f (Just (p+q))` we'll build a thunk for `p+q`. But `f` always evaluates it, so that thunk is useless; we could use call-by-value. When we have unboxed sums, we can do worker/wrapper for `f` too. In contrast, you seem to be thinking about the benefits for nested CPR perhaps, in comment:3 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12364#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler