-fwarn-incomplete-patterns, not always warns

[Simon Peyton-Jones]

It's a GHC weakness.  I've added your example to the currently-open bug
for it:

http://sourceforge.net/tracker/index.php?func=detail&aid=1075259&group_i
d=8032&atid=108032

Simon
| -----Original Message-----
| From: glasgow-haskell-users-bounces at haskell.org
[mailto:glasgow-haskell-users-
| bounces at haskell.org] On Behalf Of Neil Mitchell
| Sent: 01 December 2005 20:56
| To: glasgow-haskell-users at haskell.org
| Subject: -fwarn-incomplete-patterns, not always warns
| 
| Hi,
| 
| I have been playing around with -fwarn-incomplete-patterns under GHC
| 6.4.1 on Windows.
| 
| -- no warning
| ex1 x = ss
|     where (s:ss) = x
| 
| -- no warning
| ex2 x = let (s:ss) = x in ss
| 
| --    Warning: Pattern match(es) are non-exhaustive
| --             In a case alternative: Patterns not matched: []
| ex3 x = case x of ~(s:ss) -> ss
| 
| I have translated all 3 functions using the rules supplied in the
| Haskell 98 report, so they all have the same meaning, but only one
| gives an error. Is it intentional to ignore where/let pattern matches?
| 
| Thanks
| 
| Neil
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