#7258: Compiling DynFlags is jolly slow -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: deriving-perf Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): So apparently, good shape (linear-ish performance): {{{ D <$> a1 <*> a2 <*> a2 <*> ... <*> aN }}} Bad shape (exponential-ish performance): {{{ do v1 <- a1 v2 <- a2 v3 <- a3 ... vN <- aN return $ D v1 v2 v3 ... vN }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7258#comment:44 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler