- Haskell - Haskell.org

readfile not so lazy
by Hal Daume III 09 Jan '02

09 Jan '02

Why, in the following program: > createFile = unsafePerformIO $ > writeFile "test.xxx" > ('1' : (take 10000000 (repeat '0')) ++ "1") > > processFile = > unsafePerformIO $ > do f <- readFile "test.xxx" > return (dropWhile (=='0') $ > dropWhile (/='0') f) does the amount of memory used by 'processFile' depend on the size of the file created? that is, if the take 10000000 is replaced by 100000000, the execution of processFile takes (around) ten times as much memory. it appears that it's storing all of f in memory even though all it really needs is the last character. how can i make this more lazy? (this was all done in ghc) - Hal

1 0

differentiation. Reply
by S.D.Mechveliani 09 Jan '02

09 Jan '02

Zhe Fu <fuzhezheng(a)hotmail.com> writes > Is there any built-in functions in Haskell to implement > diffential operation and partial diffential operation? > Or can anyone give me some advices about how to implement them > with Haskell? Thanks. There are no differential operators in Haskell-98 standard library, nor even polynomial arithmetic. Very probably, there exist application programs treating differential operators. Try to search in http://www.haskell.org If you are going to implement differential operators, try first to implement, for example, polynomial multiplication. After this, differentiation would not look hard. But it depends on what one wants to differentiate, one has to formulate first what kind of expressions are supposed to be differentiated. ----------------- Serge Mechveliani mechvel(a)botik.ru

2 2

[qforeign] examples/Glob.hsc patch for segv on nomatch
by Jens Petersen 09 Jan '02

09 Jan '02

This patch fixes a problem with the glob binding example in qforeign, where it would segfault when no files were found for the glob exp. Btw, Qrczak, have you considered adding the glibc glob flag extensions to Glob (eg GLOB_BRACE, GLOB_TILDE, etc)? They would be nice to have too, but I guess there is the issue of portability? In that case perhaps they should then going into a separate submodule? Jens ps There is also still the issue with attr_set in the Curses.hsc binding, which I haven't managed to resolve yet (except by working "around" it by using attrset instead). 2002-01-09 Jens Petersen <juhp(a)01.246.ne.jp> * examples/Glob.hsc (glob): Test pathc before trying to read pathv to avoid segfault on nomatch. Index: examples/Glob.hsc =================================================================== RCS file: /cvsroot/qforeign/qforeign/examples/Glob.hsc,v retrieving revision 1.4 diff -u -r1.4 Glob.hsc --- examples/Glob.hsc 2001/03/18 19:40:00 1.4 +++ examples/Glob.hsc 2002/01/09 14:18:14 @@ -81,8 +81,12 @@ (#const GLOB_NOMATCH) -> GlobNoMatch (#const GLOB_NOSPACE) -> GlobNoSpace _ -> GlobOther - pathv <- (#peek glob_t, gl_pathv) ptr - paths <- peekArray0 nullPtr pathv >>= mapM peekCString + pathc <- (#peek glob_t, gl_pathc) ptr :: IO CUInt + paths <- if pathc > 0 then + do + pathv <- (#peek glob_t, gl_pathv) ptr + peekArray0 nullPtr pathv >>= mapM peekCString + else return [] globfree ptr return (res, paths)

1 0

Extended deadline
by icalp2002＠informatica.uma.es 09 Jan '02

09 Jan '02

We apologize for possible multiple postings. One week extension of paper submission deadline and invited speakers ------------------------------------------------------------------------- Within the last two weeks the conference chairs have received multiple requests to extend the paper submission deadline. In response to it, the submission deadline for papers is extended for a week (until 23:59:59 GMT of 21th January). Note that we will not be able to extend this deadline any further. The complete list of invited speakers is as follows: Manuel Hermenegildo Heikki Mannila Madhav Marathe Andrew Pitts John Reif The 2002 Gödel Prize and The 2002 EATCS Prize: Maurice Nivat For information about the conference visit the web page: http://www.lcc.uma.es/ICALP2002 Best Regards,

1 0

The Fortune Lounge online Casino!
by thefortune＠cc.com 09 Jan '02

09 Jan '02

BODY></TABLE></CENTER></TD></TR> <TR> <TD borderColor=#996699 bgColor=#ffffff colSpan=2 border="2"> <CENTER>Email us at <A href="mailto:support@fortunelounge.com%20">support(a)fortunelounge.com </A>or call our 24 hour toll-free numbers now:</CENTER> <CENTER> <TABLE borderColor=#cc3366 cellSpacing=3 cellPadding=3 border=0> <TBODY> <TR> <TD>USA:</TD> <TD>1-800-587-9036</TD> <TD>Portugal:</TD> <TD>800-827-002 </TD></TR> <TR> <TD>Canada:</TD> <TD>1-877-846-0527</TD> <TD>Hong Kong:</TD> <TD>800-901-014 </TD></TR> <TR> <TD>Australia: </TD> <TD>1-800-706-903</TD> <TD>Italy:</TD> <TD>800-782-446 </TD></TR> <TR> <TD>United Kingdom:</TD> <TD>0-800-056-9578</TD> <TD>Israel:</TD> <TD>1-800-945-1602 </TD></TR> <TR> <TD>Germany:</TD> <TD>0-800-180-0948</TD> <TD>France:</TD> <TD>0-800-918-780 </TD></TR></TBODY></TABLE></CENTER> <CENTER>For our Terms and Conditions,<A target=_blank href="http://www.fortunelounge.com/terms.asp?btag=562_415_1264_146_1880">please click here.</A> </CENTER></TD></TR></TBODY></TABLE></CENTER>  </TD></TR> <TR> <TD colSpan=7><IMG height=13 src="Newsletter001_10.gif" width=650></TD></TR></TBODY></TABLE></CENTER></BODY></HTML> To be permanently removed from future optservices.com mailings, simply reply to this email with REMOVE in the subject and/or body of message. To remove other addresses visit our remove page at <"http://www.optservices.com/asp/remove.asp">

1 0

how to implement the differential operation with Haskell?
by Zhe Fu 09 Jan '02

09 Jan '02

Is there any built-in functions in Haskell to implement diffential operation and partial diffential operation? Or can anyone give me some advices about how to implement them with Haskell? Thanks.

1 0

(no subject)
by D.Wakeling＠exeter.ac.uk 08 Jan '02

08 Jan '02

Hello, Is there any reason why the "gap" in a string literal is defined as gap -> \whitechar {whitechar}\ (in Section 2.6 of the report), rather than gap -> \whitespace\ ? The second, more liberal, definition of "gap" seems more natural. Moreover, it would allow comments in the gaps, which I would find useful. For example, classHeader :: String classHeader = "\xca\xfe\xba\xbe\ -- magic number \\x00\x03\ -- minor version \\x00\x2d" -- major version David ------------------------------------------------------------------------------- Dr. David Wakeling, School of Engineering and Computer Science University of Exeter, Exeter, Devon, EX4 4PT. unofficial web page: http://www.dcs.ex.ac.uk/~david -------------------------------------------------------------------------------

1 0

Re: Haskell compared to Clean?
by Krasimir Angelov 08 Jan '02

08 Jan '02

Hi Currently I translate Clean Object I/O library to Haskell. The process is near its completion. I agree that Clean and Haskell are very similar. __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! Mail! http://promo.yahoo.com/videomail/

1 0

Haskell compared to Clean?
by herman_graal＠europe.com 07 Jan '02

07 Jan '02

I'm resending this since my last try hasn't shown up on the list; sorry if two messages will end up there... ;-) -----Original Message----- From: herman_graal(a)europe.com Sent: Mon, 07 Jan 2002 07:58:58 +0800 To: haskell(a)haskell.org Subject: Haskell compared to Clean? Hi, I've been using Haskell for some time but recently found out about Clean. The languages seem very similar, but I've seen some statements that Clean is supposed to be faster (it was unclear if the compilation or execution time was meant). Have anyone here on the Haskell list tried Clean? What is your impressions? Advantages and disadvantages? To me the languages seem very similar. Any info appreciated. Best regards, Herman Graal -- _______________________________________________ Sign-up for your own FREE Personalized E-mail at Mail.com http://www.mail.com/?sr=signup 1 cent a minute calls anywhere in the U.S.! http://www.getpennytalk.com/cgi-bin/adforward.cgi?p_key=RG9853KJ&url=http:/…

1 0

(no subject)
by sekar＠cs.sunysb.edu 07 Jan '02

07 Jan '02

Senior Researcher Position Available We invite applications for a senior researcher position funded by a DoD University Research Initiative (URI) award in the area of Critical Infrastructure Protection and High Confidence Software (CIP/SW). This award is prestigious, with only 20 URI awards having been made nationwide. The position is available immediately for a period of upto two years at an annual salary between $65,000 and $75,000. The CIP/SW fellow will work with researchers from Stony Brook's Center for Cybersecurity, and especially the faculty from Secure and Reliable Systems Group and Formal Methods Group. The theme of our CIP/SW project is Model-Carrying Code (MCC), a new approach for ensuring security of mobile code. The MCC approach employs a combination of compile-time verification and runtime monitoring/enforcement techniques. Candidates must have a PhD in Computer Science or a closely related field. Masters Degree with exceptionally strong research experience will also be considered. Preference will be given to candidates specializing in one of the following areas: computer/network security, programming language/compilers, formal methods, operating systems and networks. Strong background in programming, and/or UNIX operating systems would be preferred. Applications should be forwarded to Prof. R. Sekar (sekar(a)cs.sunysb.edu) Stony Brook is situated on Long Island, approximately 50 miles east of New York City. The University is two miles south of the Long Island Sound and 20 miles north of the Atlantic Ocean and picturesque Long Island beaches. The famous beaches and mansions of The Hamptons are about 40 miles to the southeast. For additional information, please visit our laboratory web pages at http://seclab.cs.sunysb.edu/seclab/onrsearch.html, http://seclab.cs.sunysb.edu and http://www.cs.sunysb.edu/~lmc.

1 0