[Haskell-cafe] view patterns
drl at cs.cmu.edu
Sat Nov 8 14:56:57 EST 2008
Yes, the current overlap checker thinks all view patterns are
overlapped. The pattern overlap/exhaustiveness checker needs to be
rewritten to account for GADTs and view patterns.
You can use -fno-warn-overlapping-patterns to suppress these warning
(along with any actual overlaps, though, unfortunately).
On Nov05, Cale Gibbard wrote:
> 2008/11/5 Cetin Sert <cetin.sert at gmail.com>:
> > <interactive>:1:4:
> > Warning: Pattern match(es) are overlapped
> > In the definition of `emp':
> > emp ((has -> True)) = ...
> > emp ((has -> False)) = ...
> > Why do I get this error in ghc or when I try to compile a file with view
> > patterns?
> > (using -fglasgow-exts and -XViewPatterns, ghc 6.10.1)
> This is a bug which appears to be known about:
> - Cale
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