- Hugs-Bugs - Haskell.org

pattern bug?
by Hamilton Richards 15 Jul '01

15 Jul '01

Should this compile? f :: (a -> a -> a) -> Int f (+) = 0 f (*) = 1 f (&&) = 2 f (||) = 3 Hugs (Version: February 2001) accepts it without complaint. Regards, --HR ------------------------------------------------------------------ Hamilton Richards, PhD Department of Computer Sciences Senior Lecturer Mail Code C0500 512-471-9525 The University of Texas at Austin Taylor Hall 5.138 Austin, Texas 78712-1188 ham(a)cs.utexas.edu hrichrds(a)swbell.net ------------------------------------------------------------------

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hugs #of reductions
by Ch. A. Herrmann 09 Jul '01

09 Jul '01

Hi! We observed that often the evaluation of the same expression again requires fewer reductions than before. It seems that the number of reductions hugs reports (:set +s) does not only depend on the program loaded and the expression evaluated but also on other things. What are they? Is there a way to produce deterministic results; e.g., does a freshly loaded hugs on the same machine with the same program and evaluated expression always deliver the same number of reductions? Cheers -- Christoph Herrmann Postdoctoral Research Associate University of Passau, Germany E-mail: herrmann(a)fmi.uni-passau.de WWW: http://brahms.fmi.uni-passau.de/cl/staff/herrmann.html

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Perhaps a Very Small Bug
by Iain McNaughton 28 Jun '01

28 Jun '01

Hi ! This is just to report something which surprised me, and which may perhaps be a very small bug ( or possibly just me being dumb ). I was using WinHugs as a calculator. From the main command prompt in WinHugs, I typed the following: 102.0*201.0 + 103.0*202.0 + 102.0*201.0 +102.0*202.0 + 102.5*200.5 I then hit 'return', and was presented with the answer: 102965.0 Now, the actual answer is 102965.25, as Hugs itself knows; when I typed: $$ - 102965 and hit 'return', I duly got the answer: 0.25 I tinkered around with a few other numbers, and what seems to be happening is that Hugs is rounding the calculation result up or down, in the way that you'd expect if you were only showing a specific number of significant figures. This seems reasonable ( although only 6 significant figures seems a bit on the low side ), but it's rather misleading to then show the '0' after the decimal point ! I'd be interested to hear your comments. Thanks for your ( hoped for ) advice on this. Yours sincerely, Iain McNaughton. -- Iain McNaughton

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Cannot build superclass instance
by Johannes Waldmann 28 Jun '01

28 Jun '01

The following program import Complex instance Ord a => Ord (Complex a) where (x1 :+ y1) `compare` (x2 :+ y2) = (x1, y1) `compare` (x2, y2) gives the message ERROR Bug.hs:3 - Cannot build superclass instance *** Instance : Ord (Complex a) *** Context supplied : Ord a *** Required superclass : Eq (Complex a) What is hugs' problem here? It compiles with ghc. -- -- Johannes Waldmann ---- http://www.informatik.uni-leipzig.de/~joe/ -- -- joe(a)informatik.uni-leipzig.de -- phone/fax (+49) 341 9732 204/252 --

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output of heap profiler
by Malcolm Wallace 27 Jun '01

27 Jun '01

Hi to all in Hugs-land. This bug report concerns the generation of heap profiling data by Hugs98 (Feb 2000). In the middle of valid data in the .hp file, there are interspersed invalid items, e.g. foldr 17 or 2 v141 3 Undefined member: member: 1 getArgs 2 FilePos 6 It looks like some error message from a printing routine is being included by mistake. The graph-producing tool hp2ps complains hp2ps: profile.hp, line 57: integer must follow identifier If you need a test program to reproduce the problem, I can supply one. I was using 'hugs -98 -d200' as a command-line. Regards, Malcolm ----------------------------------------- Malcolm.Wallace(a)cs.york.ac.uk Dr Malcolm Wallace (functional programming research) +44 1904 434756 Department of Computer Science, University of York, YORK YO10 5DD, U.K.

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unexpected signal with +m
by Saswat Anand 23 Jun '01

23 Jun '01

When I run "hugs -98 +m", hugs gives "unexpected signal" and crashes for the expression "Just 3 > Just 2". Thanks, Saswat

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RE: Bug or an Issue?
by Julian Seward (Intl Vendor) 22 Jun '01

22 Jun '01

| What am i doing wrong? You can't define functions on the Hugs command line. You need to put the function definition in a text (.hs) file and ask Hugs to read that file. J

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Bug or an Issue?
by Tige 22 Jun '01

22 Jun '01

Prelude> square x = x * x ERROR - Syntax error in input (unexpected `=') I can't seem to define anything on Haskell. It says Unexpected '='. I am running Hugs98 latest 2001 Version right off the Website Windows Install File. What am i doing wrong?

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runhugs requires non-literate program
by Dean Herington 15 Jun '01

15 Jun '01

Contrary to the documention, it appears that runhugs (used explicitly or via #!) requires the program to be non-literate. I'm running Hugs versions of February 2000 and February 2001 on Solaris machines. buzzard(163)% cat ./hello-lit #!/stotts2/epa1/hugs98-Feb2001/release/solaris/bin/runhugs > module Main where > main = putStrLn "Hello, World!" buzzard(164)% ./hello-lit runhugs: Error occurred Reading file "./hello-lit": Parsing ERROR ./hello-lit:3 - Syntax error in input (unexpected symbol ">") buzzard(165)% cat ./hello-nonlit #!/stotts2/epa1/hugs98-Feb2001/release/solaris/bin/runhugs module Main where main = putStrLn "Hello, World!" buzzard(166)% ./hello-nonlit Hello, World! buzzard(167)%

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File associations with hugs 98 for windows
by Alex Summers 15 Jun '01

15 Jun '01

Hi there, I have recently started using Hugs 98 for Windows (previously was using the MSDOS version). In general it works fine and contains lots of useful features. However, in contrast to the MSDOS version, if I associate .hs files with hugs98 for windows, and then attempt to open them directly (double-clicking on the script file) then it fails with an error such as : ERROR ""C:\HaskellProject\HaskellProject(alex-new).hs"": Unable to open file ""C:\HaskellProject\HaskellProject(alex-new).hs"" It seems that for some reason the filename gains two sets of double quotes which makes it unreadable. I can only guess that Windows supplies one set with its file-passing convention, and hugs supplies the other. Interestingly, I can still edit the file (even from the hugs prompt), as WordPad accepts the filename correctly. But any attempt to load it at the hugs prompt fails, and I have to remove it from the script manager and then add it manually. In the script manager the filename has a single set of double quotes, which script files (e.g. the prelude) do not normally have here. Any help would be greatly appreciated. Thanks in advance, Alex Summers

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