#11418: Suggest correct spelling when module is not found because of typo -------------------------------------+------------------------------------- Reporter: syd | Owner: Type: feature request | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 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 thomie): This feature could be called `-fhelpful-import-errors`. Do you think it should be enabled by default? We would have to ask others as well. Not only does scanning a directory take time, there is also a memory cost. A pretty bad scenario would be running ghc in $HOME. On my system: {{{ $ find ~ > all-files-in-home $ wc -l all-files-in-home 168014 all-files-in-home $ du -h all-files-in-home 14M all-files-in-home }}} You could exclude subdirectories that don't start with an uppercase letter from the scan. But Windows paths are case-insensitive, so it wouldn't help there. Or stop scanning after the first N=1000 or so files (do some measurements to see what's reasonable). How about this partial solution: * A lot of people use Cabal for library development * Cabal already asks you to specify all known modules in either `exposed- modules` or `other-modules` (I guess you could make typos here..) * Cabal already passes this list of modules to GHC * So GHC already knows the names of all modules that could possibly be imported (not quite, see https://github.com/haskell/cabal/issues/2982#issuecomment-169786310) * Use that list of modules to make spelling suggestions on import errors -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11418#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler