Re: [GHC] #851: Incomplete-pattern checking for n+k patterns is not implemented
#851: Incomplete-pattern checking for n+k patterns is not implemented ---+ Reporter: simonpj | Owner: Type: bug | Status: closed Priority: low | Milestone: _|_ Component: Compiler |Version: 6.4.2 Resolution: wontfix | Keywords: warnings Difficulty: Unknown | Os: Unknown/Multiple Testcase: ds061 | Architecture: Unknown/Multiple Failure: None/Unknown | ---+ Changes (by igloo): * status: new => closed * failure: => None/Unknown * resolution: => wontfix Comment: The !NoNPlusKPatterns proposal was accepted for H'2010, so I don't think it is worth spending time on this. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/851#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #3382: Panic in tidyNPat when using N+k patterns with overloaded strings
#3382: Panic in tidyNPat when using N+k patterns with overloaded strings
-+--
Reporter: batterseapower|Owner:
Type: bug | Status: closed
Priority: normal|Milestone:
Component: Compiler | Version: 6.10.4
Severity: normal| Resolution: fixed
Keywords:| Difficulty: Unknown
Testcase: deSugar/should_run/T3382 | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
-+--
Changes (by simonpj):
* testcase: => deSugar/should_run/T3382
* difficulty: => Unknown
* status: new => closed
* resolution: => fixed
Comment:
Ah yes, excellent point. Fixed by
{{{
Mon Jul 20 07:12:26 GMT Daylight Time 2009 simo...@microsoft.com
* Fix Trac #3382: desugaring of NPats
Max spotted that the short-cut rules for desugaring NPats (where
we compare against a literal) were wrong now that we have overloaded
strings.
}}}
thanks
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3382#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler___
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
[GHC] #3382: Panic in tidyNPat when using N+k patterns with overloaded strings
#3382: Panic in tidyNPat when using N+k patterns with overloaded strings
-+--
Reporter: batterseapower| Owner:
Type: bug | Status: new
Priority: normal| Component: Compiler
Version: 6.10.4| Severity: normal
Keywords:| Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
-+--
Spotted this while reading the source code to tidyNPat. It looked dubious
to me, and indeed it is:
{{{
{-# OPTIONS_GHC -XOverloadedStrings #-}
module Main where
import Data.String
instance IsString Int where
fromString x = 1337
f :: Int -> String
f "hello" = "correct"
f _ = "false"
main = do
print $ f 1337
print $ f 1338
}}}
Result:
{{{
mbolingbr...@mb566 ~/Programming/Checkouts
$ ghc --make Boog.hs
[1 of 1] Compiling Main ( Boog.hs, Boog.o )
ghc: panic! (the 'impossible' happened)
(GHC version 6.10.3 for i386-apple-darwin):
tidyNPat
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3382>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler___
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #851: Incomplete-pattern checking for n+k patterns is not implemented
#851: Incomplete-pattern checking for n+k patterns is not implemented --+- Reporter: simonpj | Owner: Type: bug | Status: new Priority: low | Milestone: _|_ Component: Compiler |Version: 6.4.2 Severity: normal| Resolution: Keywords: warnings | Difficulty: Unknown Testcase: ds061 | Architecture: Unknown Os: Unknown | --+- Changes (by igloo): * keywords: => warnings * testcase: => ds061 -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/851> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #851: Incomplete-pattern checking for n+k patterns is not implemented
#851: Incomplete-pattern checking for n+k patterns is not implemented ---+ Reporter: simonpj | Owner: Type: bug | Status: new Priority: low | Milestone: _|_ Component: Compiler |Version: 6.4.2 Severity: normal| Resolution: Keywords:| Os: Unknown Difficulty: Unknown | Architecture: Unknown ---+ Changes (by simonpj): * milestone: => _|_ * priority: normal => low Comment: See Task #595 -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/851> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
[GHC] #851: Incomplete-pattern checking for n+k patterns is not implemented
#851: Incomplete-pattern checking for n+k patterns is not implemented
-+--
Reporter: simonpj |Owner:
Type: bug | Status: new
Priority: normal|Milestone:
Component: Compiler | Version: 6.4.2
Severity: normal| Keywords:
Os: Unknown | Difficulty: Unknown
Architecture: Unknown |
-+--
The check for incomplete patterns does not understand about n+k patterns.
Here's an example:
{{{
f 0 = True
f (n+1) = False
}}}
GHC says, rather confusingly:
{{{
Warning: Pattern match(es) are non-exhaustive
In the definition of `f':
Patterns not matched: #x with #x `notElem` [0#]
}}}
The reason is in {{{compiler/deSugar/Check.hs}}} which says
{{{
-- Horrible hack. The simplify_pat stuff converts NPlusK pats to
WildPats
-- which of course loses the info that they can fail to match. So
we
-- stick in a CanFail as if it were a guard.
-- The Right Thing to do is for the whole system to treat NPlusK
pats properly
}}}
See ticket:595
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/851>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler___
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: Erroneous warning with n+k patterns
OK, well I've fixed this one. But not overlap warnings in general Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:glasgow-haskell-bugs- | [EMAIL PROTECTED] On Behalf Of Ian Lynagh | Sent: 20 August 2005 02:39 | To: glasgow-haskell-bugs@haskell.org | Subject: Erroneous warning with n+k patterns | | | Hi all, | | This function: | | g :: Int -> Int | g (x+1) = 1 | g _ = 0 | | (erroneously) gives this warning: | | Warning: Pattern match(es) are overlapped | In the definition of `g': g _ = ... | | I'm not sure if this is covered by the first item on | http://www.haskell.org/ghc/docs/latest/html/users_guide/bugs.html | but if so (well, probably even if not; I've grown quite attached to | -Wall -Werror) then I'd like to add my voice to those who would like to | see the mentioned overhaul done. | | | Thanks | Ian | | ___ | Glasgow-haskell-bugs mailing list | Glasgow-haskell-bugs@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Erroneous warning with n+k patterns
Hi all, This function: g :: Int -> Int g (x+1) = 1 g _ = 0 (erroneously) gives this warning: Warning: Pattern match(es) are overlapped In the definition of `g': g _ = ... I'm not sure if this is covered by the first item on http://www.haskell.org/ghc/docs/latest/html/users_guide/bugs.html but if so (well, probably even if not; I've grown quite attached to -Wall -Werror) then I'd like to add my voice to those who would like to see the mentioned overhaul done. Thanks Ian ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: n + k patterns
Good point. Fixed in the head, but not in 6.0 Thanks Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On | Behalf Of Ralf Hinze | Sent: 28 May 2003 20:40 | To: GHC bugs | Subject: n + k patterns | | GHCi infers for | | > fac 0 = 1 | > fac (n + 1) = (n + 1) * fac n | | the following type | | / _ \ /\ /\/ __(_) | / /_\// /_/ / / | | GHC Interactive, version 5.04.2, for Haskell 98. | / /_\\/ __ / /___| | http://www.haskell.org/ghc/ | \/\/ /_/\/|_| Type :? for help. | | Loading package base ... linking ... done. | Loading package haskell98 ... linking ... done. | Compiling Main ( Fac.lhs, interpreted ) | Ok, modules loaded: Main. | *Main> :t fac | forall a. (Num a, Ord a) => a -> a | | The Report, however, states that | | 3.17.2 Informal Semantics of Pattern Matching | <...> | An n+k pattern can only be matched against a value in the class Integral. | | Cheers, Ralf | | ___ | Glasgow-haskell-bugs mailing list | [EMAIL PROTECTED] | http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
n + k patterns
GHCi infers for > fac 0 = 1 > fac (n + 1) = (n + 1) * fac n the following type / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 5.04.2, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \/\/ /_/\/|_| Type :? for help. Loading package base ... linking ... done. Loading package haskell98 ... linking ... done. Compiling Main ( Fac.lhs, interpreted ) Ok, modules loaded: Main. *Main> :t fac forall a. (Num a, Ord a) => a -> a The Report, however, states that 3.17.2 Informal Semantics of Pattern Matching <...> An n+k pattern can only be matched against a value in the class Integral. Cheers, Ralf ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
