February 2003 - Hugs-Bugs

Re:
by wr 28 Feb '03

28 Feb '03

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bug in hugs with Int handling for mac os x?
by Onne Gorter 27 Feb '03

27 Feb '03

hello, program: sieve :: [Int] -> [Int] sieve (x:xs) = x: sieve [c|c<-xs, mod c x > 0] and then run: sieve [2..] breaks after number 16477 with an 'Illegal instruction' (the mac os X native signal) and hugs quits. Now, I expected an 'out of memory' or a 'number overflow' or 'stack overflow' or something thelike, but not this, this implies a buffer overrun or something. I am not sure how anyways, just reporting, my hardware is a white iBook 2002 600Mhz running mac os X 10.2.4 the software used is Hugs 98 Version November 2002. -Onne

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a module system bug
by Iavor S. Diatchki 26 Feb '03

26 Feb '03

hello, here is another module system bug: module A where data A = K module B where import A data B = K f K = 'k' Hugs should report that the use of "K" in the definition of "f" is ambiguous (as it may refer to the "K" defined in either A or B). Instead, it infers the type "B -> Char" for "f", so it looks like the local constructor shadows the imported one. bye iavor -- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================

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module bug?
by Hamilton Richards 25 Feb '03

25 Feb '03

Version: November 2002 Platform: Mac OS X 10.2.4 Problem: hugsHIsEOF and hGetLine don't work. Exactly the same script --using hugsHIsEOF and hGetLine-- works fine in the Feb 2001 MacHugs running in Classic mode. Thanks, --Ham -- ------------------------------------------------------------------ Hamilton Richards Department of Computer Sciences Senior Lecturer The University of Texas at Austin 512-471-9525 1 University Station C0500 Taylor Hall 5.138 Austin, Texas 78712-1188 ham(a)cs.utexas.edu hrichrds(a)swbell.net ------------------------------------------------------------------

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Win32 Hugs bug: Termination without notification
by Neil Mitchell 25 Feb '03

25 Feb '03

Hi The following fragment of program is clearly wrong, but causes a complete exit of Hugs, without warning of any kind. Code: func | func = True Invoking: func My system: Hugs 98 - Nov 2002 edition Windows XP Professional This bug is reproducable under both the console version and the graphical version. Thanks, if you need any further information just ask Neil

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arguments to the main function throught runhugs
by thiagohb 19 Feb '03

19 Feb '03

Hello, I'm a student in Ouro Preto's University (Brazil) and I have a problem: How can I pass arguments to the main function throught runhugs? I'll need to use a string in the main function. How can I catch the string from command line? For example: runhugs main.hsx test Thank you. Thiago Braga.

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Trex and module system
by Iavor S. Diatchki 18 Feb '03

18 Feb '03

hello, the recent updates of the module system seem to have broken Trex. the problem is that Hugs.Trex tries to export "EmptyRec" which is a data constructor and so cannot be named explicitly in an export list. (interestingly enough the Prelude does the same, but no error seems to occur) a quick fix that seems to work is to change the Hugs.Trex module as follows: module Hugs.Trex( module Hugs.Trex ) where import Hugs.Prelude as Hugs.Trex -- ( Rec, EmptyRec, EmptyRow ) of course now Trex exports the whole of the Prelude, but hey it is a quick fix :-) bye iavor -- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================

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winhugs crashes on C stack overflow
by Jan Reineke 14 Feb '03

14 Feb '03

Hi, I am new to Haskell and functional programming in general, but I think that I have found a bug in Winhugs. When I call "wurzel 5" in the "dos-mode"-hugs after loading the attached file I get "ERROR - C stack overflow", which is ok. Winhugs crashes in the same situation. In my German Win2k version it says "winhugs.exe hat Fehler verursacht und wird geschlossen. Starten Sie das Programm neu. Ein Fehlerprotokoll wird erstellt." which means something like "winhugs.exe has created an error and is going to be closed. Restart the program." Is this a known issue? Regards, Jan Reineke absolutevalue :: (Double -> Double) absolutevalue x = if (x < 0) then -x else x newtoniteration :: (Double -> Double) -> (Double -> Double) -> Double -> Double newtoniteration g gprime x = if (absolutevalue(g x/gprime x) < 0.01) then x else newtoniteration g gprime x-(g x/gprime x) wurzel a = newtoniteration (\x -> (x*x-a)) (\x -> x*x) 2 f a x = x*x-a fprime x = x*x wurzelalternative a = newtoniteration (f a) fprime 2

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module system bug
by Iavor S. Diatchki 13 Feb '03

13 Feb '03

hi, i seem to have run into a module system bug, which is illustrated by the following example: module A where data T = T module B where import A hiding (T()) -- note the parens after T v = T Hugs complains that "T" is an undefined constructor. This would be the correct behaviour if T didn't have the () after it, as both the type and the constructors by the name T should be hidden. however, the parens indicate that the type/class T should be hidden, and also all the constructors listed in the parens. since the constructor T is not listed, it should not be hidden. basically, if a name has parens after it, it always refers to a type/class. this is not a big thing, but is ocasionally useful, and more importantly, it is nice when one can load a program with both GHC and Hugs, which i am glad to say happens more and more often. bye iavor -- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================

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another module system bug
by Iavor S. Diatchki 13 Feb '03

13 Feb '03

hi, here is another module system bug: module A where data A = A { t :: Int } module B where import A data B = B { t :: Char } Hugs complains that the selector "t" is already defined. This is wrong, since this error should only be reported if the selector is used ambiguously (e.g. with an unqualified name). bye iavor -- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================

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