- Haskell - Haskell.org

getEvent Doubts
by Andre W B Furtado 28 Mar '01

28 Mar '01

[Sorry about the previous email subject :) ] In Hugs Graphics Library, many procedures call the function getEvent with a Window as the parameter. But getEvent is defined as below: getEvent :: Events -> IO Event How does this work? I've tryied to do something similar and got the following error message (in GHC): Couldn't match `Events' against `Window' Expected type: Events Inferred type: Window In the first argument of `getEvent', namely `w' In a do statement: e <- getEvent w In time: my "Window" is defined as following data Window = MkWindow { win :: GLUT.Window, -- the real window events :: Events -- the event stream } And in Hugs Graphics Library the "Window" is defined as: data Window = MkWindow { wnd :: WND, -- the real window events :: Events, -- the event stream graphic :: IORef (Draw ()) -- the current graphic } Thanks, Andre

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Difficulties compiling hmake / HaXml
by Lescher Christian 28 Mar '01

28 Mar '01

I want to use HaXml, and since hmake is required first, I'm currently trying to build hmake with GHC. Unfortunately "make" fails; I get the above errors message. What am I doing wrong here? I use GHC4.08.2 (InstallShield version) under WinNT4/Cygwin1.1.8. Christian make[1]: Entering directory `/test-hmake/hmake-2.02/src/interpreter' mkdir -p /test-hmake/hmake-2.02/targets/ix86-CYGWIN_NT-4.0/obj/interpreter /test-hmake/hmake-2.02/script/hmake -ghc HInteractive -d/test-hmake/hmake-2.02/t argets/ix86-CYGWIN_NT-4.0/obj/interpreter Fail: Can't find module Posix in . Or in standard libraries at /ghc/ghc-4.08.2/lib/imports/std /ghc/ghc-4.08.2/lib/imports/data /ghc/ghc-4.08.2/lib/imports/lang /ghc/ghc-4.08.2/lib/imports/posix /ghc/ghc-4.08.2/lib/imports/net /ghc/ghc-4.08.2/lib/imports/num /ghc/ghc-4.08.2/lib/imports/text /ghc/ghc-4.08.2/lib/imports/util /ghc/ghc-4.08.2/lib/imports/win32 /ghc/ghc-4.08.2/lib/imports/concurrent Asked for by: HmakeConfig.hs [Check settings of -I or -P flags?] Stop - hmake dependency error. make[1]: *** [/test-hmake/hmake-2.02/lib/ix86-CYGWIN_NT-4.0/HInteractive.exe] Er ror 1 make[1]: Leaving directory `/test-hmake/hmake-2.02/src/interpreter' make: *** [targets/ix86-CYGWIN_NT-4.0/hmake_g] Error 2

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Duvidas
by Andre W B Furtado 28 Mar '01

28 Mar '01

In Hugs Graphics Library, many procedures call the function getEvent with a Window as the parameter. But getEvent is defined as below: getEvent :: Events -> IO Event How does this work? I've tryied to do something similar and got the following error message (in GHC): Couldn't match `Events' against `Window' Expected type: Events Inferred type: Window In the first argument of `getEvent', namely `w' In a do statement: e <- getEvent w In time: my "Window" is defined as following data Window = MkWindow { win :: GLUT.Window, -- the real window events :: Events -- the event stream } And in Hugs Graphics Library the "Window" is defined as: data Window = MkWindow { wnd :: WND, -- the real window events :: Events, -- the event stream graphic :: IORef (Draw ()) -- the current graphic } Thanks, Andre

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Regarding open positions at IT-C
by rms 27 Mar '01

27 Mar '01

Regarding open positions at The IT-University of Copenhagen, Via the following URL you will find a detailed description of 13 positions as Associate or Assistant Professor currently open at The IT-University of Copenhagen. http://www.it-c.dk/pub_uk/db_363.html Kind Regards Personnel Department/ The IT-University of Copenhagen

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Re: the constant functor
by Tobias Haeberlein 27 Mar '01

27 Mar '01

> What is wrong with: > > class Functor ConstInt where > map f (Const n) = Const n Ups - absolutely nothing. I actually tried it with data ConstInt a = Int and didnt manage to make this an instance of class Functor. Sorry for giving the wrong example. -Tobi -- GMX - Die Kommunikationsplattform im Internet. http://www.gmx.net

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the constant functor
by Tobias Haeberlein 27 Mar '01

27 Mar '01

I am trying to make all polynomial functors (in the categorical sense) an instance of the class Functor. Consider a datatype (corresponsing to a constant functor): data ConstInt a = Const Int ConstInt is clearly a functor in the categorical sense, but is 'ConstInt' also a functor in Haskell?? Any ideas how to make 'ConstInt' an instance of class Functor? -Tobi -- GMX - Die Kommunikationsplattform im Internet. http://www.gmx.net

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Announce: Haskell libpq binding
by Wojciech Moczydlowski, Jr 23 Mar '01

23 Mar '01

The Haskell libpq (client-side PostgreSQL programming library) binding is now available to download, along with a simple DBI for Haskell, similar to this in Perl, allowing a programmer to write a database-independent code. It can be found at http://www.astercity.net/~khaliff/haskell/dbi/dbi.tgz. To compile, KDirect (http://www.astercity.net/~khaliff/kdirect) and the latest version of QForeign (http://sourceforge.net/projects/qforeign) is needed. It should compile both under ghc and nhc, yet only ghc was tested. It is no end-user product, though - there is no "install" rule in Makefile and Makefile editing is necessary, I'm afraid. If someone finds it useful or has any suggestions, I would love to hear them. Wojciech Moczydlowski, Jr

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Re: Question concerning ftp and GHC binaries for HP-UX
by Bark Fook 23 Mar '01

23 Mar '01

> Message: 1 > From: "ADAMS,RICHARD (Non-HP-Roseville,ex1)" > <richard_adams(a)non.hp.com> > To: "'haskell(a)haskell.org'" <haskell(a)haskell.org> > Subject: Question concerning ftp and GHC binaries > for HP-UX > Date: Wed, 21 Mar 2001 12:24:15 -0700 > > I would like to download the GHC binaries to our HP > 9000 machine (HP-UX > 11.0), but have access only to ftp (i.e., no Web > browser is available). > Does anyone know what ftp address to use? Also, > does anyone know whether > the GHC binaries for the HP-UX operating system will > work on HP-UX 11.0? > > I am not sure whether it is relevant, but I use > Reflection terminal > emulation to telnet from my PC to the HP 9000 > machine. Truly 'hi-tech' :) . > > Thank you. > > Sincerely, > > Richard E. Adams > Softmatrix, Inc. > Roseville, CA > Email: richard_adams(a)non.hp.com > I encountered the same problem of downloading with ftp. However, even if you succeeded in downloading, I guess it would not work as we wish:(. The system I use is HP-UX 11.00 (64-bit) HPPA 2.0. And I downloaded the version 4.08.2 for hppa1.1-hp-hpux with HTTP. It ran (without explicit errors) and output sth when input sth.hs. However, each time when I ran the sth, I got core dump. I tried to recompile the compiler (or even Happy), of course, failed with the same symptom (or unHappy). If I know anyone has successfully run GHC without incurring core dumps in HP-UX 11.00 (64-bit), I'll be very happy if Happy works too:). If I have enough time, I wish I could port it to HP-UX 11.00 (64-bit). I'm very glad to know if there exists somebody who will aid me or play together with me over 64-bit ghc for 64-bit HPUXes. Should I attack the problem from HBC or nhc98? One more bad news, SMLNJ works on HP-UX 10.20, not on HP-UX 11.00, either:-(. I've tried and failed too. One more good news, Hugs98-Feb2001 does work in HP-UX 11.00 (64-bit). I swear, where only very few tweaks are needed. But I guess it's running in 32-bit mode:-). The last kisstion: Can I build ghc from Hugs, my god? __________________________________________________ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/

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url update for Asperti & Longo: "Categories, Types and Structures"
by Jens-Ulrik Petersen 23 Mar '01

23 Mar '01

Hi Frank, Thanks for making <http://www.cs.uu.nl/people/franka/ref.html>. Good idea! "Frank Atanassow" <franka(a)cs.uu.nl> writes: > [1] Andrea Asperti and Giussepe Longo. Categories, Types and Structures. An > introduction to Category Theory for the working computer > scientist. MIT Press, 1991. > URL: http://www.dmi.ens.fr/users/longo/download.html It seems ENS's DMI bifurcated... the current url is now http://www.di.ens.fr/users/longo/download.html Maybe you could update the link on your page too. Thanks, Jens

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Re: modules and re-export
by Sigbjorn Finne 21 Mar '01

21 Mar '01

Peter Thiemann thiemann(a)informatik.uni-freiburg.de writes: > > I have a little question about the following two modules. Suppose you > want to write your own variant of the prelude that redefines a couple > of names but leaves all the rest unchanged. The Haskell report says > that the following should work: > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > module BUG2A (module BUG2A, module Prelude) where > > import Prelude hiding (head) > > head = "HEAD" > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .... > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > module BUG2B where > > import qualified Prelude > import BUG2A > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Unfortunately, this does not behave as (I think) it should: > > Reading file "BUG2B.hs": > Parsing..................................................................... ... > ERROR "BUG2B.hs": Entity "head" imported from module "BUG2A" already > defined in module "Prelude" > > However, this should be legal from my reading of the report. Hi Peter, yep, that's right, and it is a known wrinkle in Hugs' implementation of modules. I submitted a source fix which addresses just this a couple of weeks ago, http://haskell.cs.yale.edu/pipermail/hugs-bugs/2001-March/000184.html hopefully it will be included in future releases of Hugs98. hth --sigbjorn

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