#14223: Casts get in the way of join points -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: JoinPoints 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): Trouble is, the transformation that pushes continuations into join RHSs would become ill-typed. Consider {{{ case (join j x = e in case b of True -> j x |> g False -> r) of ALTS }}} Here we are allowing `j` as a join point, as proposed in comment:7. Now move that outer case inwards: {{{ join j x = case e of ALTS in case b of True -> j x False -> case r of ALTS }}} Alas, the two `(case . of ALTS)` are now scrutinising values of different types! You could say "just live with that" but I don't know what the consequences would be. Better, I think, to move the casts around somehow. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14223#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler