id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
827,Overlapped pattern warnings for lazy patterns,red5_2@…,,"The compiler appears to disregard lazy patterns when producing overlapped-pattern warnings.  Some detectable overlapped patterns are ignored as a result.  For example, the following does not produce a warning:

{{{
f x = case x of Just ~1 -> 0
                Just _  -> 1
                Nothing -> 2
}}}

This function cannot return 1 because every value that satisfies the second pattern also satisfies the first.

I think the relevant instances of overlap could be captured by treating ~() patterns as wildcards for the purpose of detecting overlapped patterns.",feature request,closed,low,,Compiler,6.4.1,fixed,overlapped,,Unknown/Multiple,Unknown/Multiple,,Unknown,,,,