#15938: Hadrian's recompilation check is extremely slow -------------------------------------+------------------------------------- Reporter: bgamari | Owner: alpmestan Type: bug | Status: new Priority: high | Milestone: 8.8.1 Component: Build System | Version: 8.6.2 (Hadrian) | 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 NeilMitchell): I investigated further, the issue is that adding a user rule match is ''O(n)'', so adding ''n'' rules is ''O(n^2^)''. I have raised a ticket to fix that at https://github.com/ndmitchell/shake/issues/632, so in time the construction in Hadrian might become efficient. But I still recommend fixing it since it's better to not enumerate all the possible paths in advance. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15938#comment:33 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler