#13623: join points produce bad code for stream fusion -------------------------------------+------------------------------------- Reporter: choenerzs | Owner: (none) Type: bug | Status: closed Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.2.1-rc1 Resolution: fixed | Keywords: JoinPoints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime | Test Case: performance bug | perf/should_runt/T13623 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Yes, it's hard for GHC to predict what "sufficient specialisation" is, and its heuristics are a bit ad hoc. Improvements there would be welcome. I'm not quite sure what changed since 8.0, but it's a squishy area so I'm not surprised that something has. Seeing where and why GHC 8.2 stopped sort of doing the full job, and what heuristic might help it continue, would be a useful piece of work. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13623#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler