[GHC] #11418: Suggest correct spelling when module is not found because of typo

[GHC]

#11418: Suggest correct spelling when module is not found because of typo
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        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:                    |
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Comment (by syd):

 Replying to [comment:16 thomie]:
 >
 > * Would ghc scan subdirectories as well (recursively?), when creating
 the map?
 It would have to, I think.
 The idea is to have a comprehensive mapping of all the (non-package)
 modules that are available for imports.

 > * Would ghc persist this map to disk? (so it could be used on the next
 `ghc --make` run)
 No. Between runs of `ghc --make` the user may want to add new modules or
 move modules and that would invalidate this map.

 > * You mentioned a trade-off before. What would the other side of the
 trade-off look like?
 If you mean the 'trade-off' in comment 9, that is no longer applicable.

 What we are trading off here is:

 Loss:
 - Cost of scanning the entire directory.

 Gain:
 - Comprehensive mapping of modules that can be imported.
 - No file-system calls to find modules while resolving the imports.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11418#comment:17>
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