#3263: Warnings for monadic values not used
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Reporter: NeilMitchell | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.10.2
Severity: normal | Resolution:
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
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Comment (by batterseapower):
A little more commentary:
* My patch does not warn on uses of {{{>>}}}, only in do-notation, where
the situation is more clear cut
* My general impression of the changes I made to GHC as a result of
having this warning are fairly positive:
* I managed to find several instances of foldM, mapM and zipWithM being
used where the _ variants were more appropriate
* A few functions had their results discarded at all use sites and could
have their return values removed outright, which is nice
* A fair number of the new _ <- bindings occured in places where people
had written a comment saying something like 'throwing this away' or
'HACK', which is a nice confirmation that the warning is providing
valuable information
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3263#comment:4>
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