September 2003 - Hugs-Bugs

Hugs home page broken
by Alastair Reid 15 Sep '03

15 Sep '03

While checking the links from my own pages, I noticed that the link: http://www.haskell.org/hugs/ gives a directory listing instead of a home page. The home page is there however. It is listed as index.htm and clicking on it gives the expected page. I suspect the problem can be fixed by either one of: 1) Rename index.htm to index.html 2) Tweak the configurations of haskell.org's web server to treat either index.html _or_ index.htm as the default page in a directory. -- Alastair Reid

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type synonyms/fun deps
by Iavor Diatchki 15 Sep '03

15 Sep '03

hello, there seems to be something wrong with the implementation of functional dependencies, or perhaps the expansion of type synonyms. i am using hugs from july 2003. the program: > module Test where > > class C a b | a -> b where > mk :: IO a > eq :: a -> a -> IO Bool > > type F = IO > > instance C a x => C [a] (F a) > > test ys = do x <- mk > xs <- mk > eq ys (x:xs) causes the error: ERROR "test.lhs":18 - Constraints are not consistent with functional dependency *** Constraint : C [a] (IO a a) *** And constraint : C [a] (F a) *** For class : C a b *** Break dependency : a -> b if 'type F = IO' is replaced with 'type F a = IO a' one gets *** Constraint : C [a] (IO [a]) if i inline the definition of 'F' things seem to work. if i remove the assumption on the instance: *** Constraint : C [a] (b a) if i remove the assumption on the instance, and eta-expand the type synonym: *** Constraint : C [a] (IO (IO a)) 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 in the Hugs98-Nov2002
by Paqui Lucio 12 Sep '03

12 Sep '03

Hi, When I have installed the Hugs98-Nov2002, the interface for windows "winhugs" is not installed (as it was in the Dec2001 version). Is that normal? Thanks in advance, Paqui ------------------------------- Paqui Lucio Dpto de LSI Facultad de Informática Paseo Manuel de Lardizabal, 1 20080-San Sebastián SPAIN Tfn: (+34) (9)43 015049 Fax: (+34) (9)43 219306 -------------------------------

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bug report: building rpm hugs98-Nov2002
by Mick Kappenburg 10 Sep '03

10 Sep '03

Hi, While trying to (re)build hugs98-Nov2002-2.src.rpm (from http://cvs.haskell.org/Hugs/pages/downloading.htm) I ran in to these two problems: rpm --rebuild hugs98-Nov2002-2.src.rpm doesn't work. In the hugs98.spec file line 50 the need for "/man/man1/hugs.1.gz" is defined, which should be the bz2 file "/man/man1/hugs.1.bz2". Afther changing the above, I tried to build the rpm package in the RPM/BUILD dir. But "make rpm" results in an error, starting with the message cat: CVS/Root: No such file or directory Creating the file (with a path in it) seems not enough. And due to lack of "cvs" skills I ended my quest. Regards, M. Kappenburg

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hugs doesn't start
by Martin 05 Sep '03

05 Sep '03

i downloaded and installed hugs for OS X but when i try and run it from the terminal i get this message Last login: Fri Sep 5 18:27:31 on ttyp1 Welcome to Darwin! [Martin-Holmans-Computer:~] martin% hugs hugs: Command not found. [Martin-Holmans-Computer:~] martin% how do i start hugs? i can find no information anywhere on this. Cheers Martin

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A bug - maybe not
by charles.huthwaite＠aonconsulting.co.uk 03 Sep '03

03 Sep '03

In my last email I noted that there was a bug on line 7! In fact there wasn't as such, rather there were the tab characters in the lines of code from my editor! Sorry about the inconvience perhaps caused. C PS: Brilliant language.... This email, together with any attachments, is for the exclusive and confidential use of the addressee(s) and may contain legally privileged information. Any other distribution, use or reproduction without the sender's prior consent is unauthorised and strictly prohibited. If you have received this message in error, please notify the sender by email immediately and delete the message from your computer without making any copies. Aon Limited Company Number: 210725 Registered Address: 8 Devonshire Square, London, EC2M 4PL Aon Limited is a member of the General Insurance Standards Council (registration 2239).

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Is this a bug?
by charles.huthwaite＠aonconsulting.co.uk 03 Sep '03

03 Sep '03

infixr 5 ~= a ~= b = a-b<h && b-a<h where h = 0.000001 zero f = until goodEnough improve 1.0 where improve b = b - f b / diff f b goodEnough b = (f b ~= 0.0) gives ERROR "train2c.hs":7 - Syntax error in input (unexpected `=') Is this a bug or have I coded it wrong? Thanks C PS: Taken from page 39 of Functional Programming by Jeroen Fokker 1995 This email, together with any attachments, is for the exclusive and confidential use of the addressee(s) and may contain legally privileged information. Any other distribution, use or reproduction without the sender's prior consent is unauthorised and strictly prohibited. If you have received this message in error, please notify the sender by email immediately and delete the message from your computer without making any copies. Aon Limited Company Number: 210725 Registered Address: 8 Devonshire Square, London, EC2M 4PL Aon Limited is a member of the General Insurance Standards Council (registration 2239).

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enumeration oddity
by Doug McIlroy 02 Sep '03

02 Sep '03

Though I'm abusing enumerations, I'm surprised that a and b give different answers (in Hugs 1.4 on Linux). Is that intended? default (Integer,Rational) a = take 3 [1/1,3/2 .. 2/1] -- [1%1,3%2,2%1] b = take 3 [1/1,3/2 ..] -- [1%1,1%1,1%1] Doug McIlroy

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