Re: [Haskell-cafe] category theory as a design tool
Hi Arnaud, you may want to look at http://mathcs.mta.ca/research/rosebrugh/Easik/ This is a java tool which allows entity design using various cat theory constraints such as sum, product and pullbacks. Brett Giles Sent from my iPhone Message: 14 Date: Wed, 22 Jun 2011 14:06:21 -0500 From: Gregg Reynolds d...@mobileink.com Subject: Re: [Haskell-cafe] Category theory as a design tool To: Arnaud Bailly arnaud.oq...@gmail.com Cc: Haskell Cafe haskell-cafe@haskell.org Message-ID: banlktingaplo7ysyggg1duxbw5ik1kl...@mail.gmail.com Content-Type: text/plain; charset=utf-8 On Tue, Jun 21, 2011 at 11:30 PM, Arnaud Bailly arnaud.oq...@gmail.com wrote: (2nd try, took my gloves off...) Hello Caf?, I have been fascinated by Cat. theory for quite a few years now, as most people who get close to it I think. I am a developer, working mostly in Java for my living and dabbling with haskell and scala in my spare time and assuming the frustration of having to live in an imperative word. More often than not, I find myself trying to use constructs from FP in my code, mostly simple closures and typical data types (eg. Maybe, Either...). I have read with a lot of interest FPS (http://homepages.mcs.vuw.ac.nz/~tk/fps/) which exposes a number of OO patterns inspired by FP. Are there works/thesis/books/articles/blogs that try to use Cat. theory explicitly as a tool/language for designing software (not as an underlying formalisation or semantics)? Is the question even meaningful? You might try: Category Theory for Computing Sciencehttp://www.cwru.edu/artsci/math/wells/pub/ctcs.html (Barr and Wells) and Conceptual Mathematics: a first introduction to categorieshttp://books.google.com/books/about/Conceptual_mathematics.html?id=o1tHw4W5MZQC (Lawvere) Kinship and Mathematical Categories (by Lawvere) is also interesting. -Gregg Thanks in advance, Arnaud ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- next part -- An HTML attachment was scrubbed... URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20110622/9f65e9e9/attachment-0001.htm -- Message: 15 Date: Wed, 22 Jun 2011 21:59:11 +0200 From: Arnaud Bailly arnaud.oq...@gmail.com Subject: Re: [Haskell-cafe] Category theory as a design tool To: Gregg Reynolds d...@mobileink.com Cc: Haskell Cafe haskell-cafe@haskell.org Message-ID: BANLkTikUtRA4=0qhluq6kzm6ijtc4wh...@mail.gmail.com Content-Type: text/plain; charset=iso-8859-1 Hello Greg and Alexander, Thanks for your replies. Funnily, I happen to own the 3 books you mentionned :-) My interest in category theory is a long standing affair... Note that owning a book, having read (most of) it and knowing a theory (or at least its principles and main concepts) is really quite a different thing from being able to apply it. Although I am certainly able to understand the Yoneda lemma, I am certainly unable to recognize the opportunity of using that knowledge to derive some new knowledge about something else. And being able to define a topoi is very different from being able to construct one or infer one out of a given category. This is an actual limitation of myself of course. Alexander's advice about using diagrams and simple notations is something I often try to do and something which most of the times end in writing a bunch of functions and data types in Haskell... What I am really looking for is a more systematic way of thinking about systems (or system fragments, or components) in a categorical way, perhaps starting with a bunch of arrows in some abstract category with objects as components and trying to infer new objects out of categorical consturctions which are made possible by the current diagrams (eg. what would be a pullback in such a category ? What would be its meaning ? Does the question itself have a meaning ?). Maybe this is really foggy and on the verge to fall into abstract nonsense... Best regards, arnaud ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Gtk2hs-users] Woes on MacOS 10.6 - linking issues -now working, but Glade is missing in v0.11 and v0.10.1 still won't compile
Hi everyone, Thanks for the variety of suggestions - I resolved this by uninstalling the Haskell-platform DMG based package and using the one from macports. I then, as mentioned elsewhere, manually modified my hsc2hs shell script to ensure the correct code was generated. However, I see that the cabal install for version 11 contains no Glade modules. I saw there was a patch posted by Andy Stewart for it a while back, is there any ETA for it for the public? I am, (so sad for me:) a bit hooped as I was going to give a demo of a program in a couple of days, but my code depends heavily on Glade and I can't seem to get the prior version of Gtk2HS (0.10.1) to compile at all. (Issues with x86_64 vs i386 - but I have tried for three hours to get the magic combination of modifications to the ghc script, the hsc2hs script and environment variable to no avail). If anyone has had luck on getting the 10.1 version to build (on a brand new install of OSx v10.6.3, macports Haskell Platform meaning GHC is 6.10.4, I'd love to hear how you did it. (I did check out the variety of tickets related to this, especially http://hackage.haskell.org/trac/ghc/ticket/3400 and the recent conversations on this list between Chris K. and Axel. On Jun 11,2010, at 2:40 AM, Axel Simon wrote: Hi Brett, On 11.06.2010, at 04:53, Brett Giles wrote: Hi Folks I seem to have Gtk2HS 0.11 installed, but not quite working. Interestingly, I can run a demo, such as the hello/World.hs example, directly in ghci. However, when I try to do a ghc --make on any code containing gtk2hs I get a link error like this: Undefined symbols: _iconv_close, referenced from: _hs_iconv_close in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_close) _iconv, referenced from: _hs_iconv in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open, _hs_iconv , _hs_iconv_close ) _iconv_open, referenced from: _hs_iconv_open in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open) ld: symbol(s) not found I do have libiconv installed as a universal library via macports. gtk, glade etc., are also universal installed via macports. I downloaded the OSX Haskell Platform package and am running ghc 6.12.1 The iconv issue is usually that you also have a libiconv that Apple ships. The platform ghc probably links against that while macports (and thus Gtk+) uses its own. I have no idea who's to blame here but I guess you should be trying to change your LD_LIBRARY_PATH or your DYLD_LIBRARY_PATH to /opt/sw since that contains the more complete version. Cheers, Axel Brett Giles Grad Student, Formal Methods, Category Theory, University of Calgary brett.gi...@ucalgary.ca ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Gtk2hs-users] Woes on MacOS 10.6 - linking issues -now working, but Glade is missing in v0.11 and v0.10.1 still won't compile SOLVED compile of 10.1
Finally figured it out - leave the scripts for ghc and hsc2hs alone and do the configure for gtk2hs 0.10.11 like this: ./configure --with-hsc2hs='--cc-flag=-m32 --ld-flag=-m32' On Jun 12,2010, at 3:53 PM, Brett Giles wrote: Hi everyone, Thanks for the variety of suggestions - I resolved this by uninstalling the Haskell-platform DMG based package and using the one from macports. I then, as mentioned elsewhere, manually modified my hsc2hs shell script to ensure the correct code was generated. However, I see that the cabal install for version 11 contains no Glade modules. I saw there was a patch posted by Andy Stewart for it a while back, is there any ETA for it for the public? I am, (so sad for me:) a bit hooped as I was going to give a demo of a program in a couple of days, but my code depends heavily on Glade and I can't seem to get the prior version of Gtk2HS (0.10.1) to compile at all. (Issues with x86_64 vs i386 - but I have tried for three hours to get the magic combination of modifications to the ghc script, the hsc2hs script and environment variable to no avail). If anyone has had luck on getting the 10.1 version to build (on a brand new install of OSx v10.6.3, macports Haskell Platform meaning GHC is 6.10.4, I'd love to hear how you did it. (I did check out the variety of tickets related to this, especially http://hackage.haskell.org/trac/ghc/ticket/3400 and the recent conversations on this list between Chris K. and Axel. On Jun 11,2010, at 2:40 AM, Axel Simon wrote: Hi Brett, On 11.06.2010, at 04:53, Brett Giles wrote: Hi Folks I seem to have Gtk2HS 0.11 installed, but not quite working. Interestingly, I can run a demo, such as the hello/World.hs example, directly in ghci. However, when I try to do a ghc --make on any code containing gtk2hs I get a link error like this: Undefined symbols: _iconv_close, referenced from: _hs_iconv_close in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_close) _iconv, referenced from: _hs_iconv in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open, _hs_iconv , _hs_iconv_close ) _iconv_open, referenced from: _hs_iconv_open in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open) ld: symbol(s) not found I do have libiconv installed as a universal library via macports. gtk, glade etc., are also universal installed via macports. I downloaded the OSX Haskell Platform package and am running ghc 6.12.1 The iconv issue is usually that you also have a libiconv that Apple ships. The platform ghc probably links against that while macports (and thus Gtk+) uses its own. I have no idea who's to blame here but I guess you should be trying to change your LD_LIBRARY_PATH or your DYLD_LIBRARY_PATH to /opt/sw since that contains the more complete version. Cheers, Axel Brett Giles Grad Student, Formal Methods, Category Theory, University of Calgary brett.gi...@ucalgary.ca -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Gtk2hs-users mailing list gtk2hs-us...@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/gtk2hs-users Brett Giles Grad Student, Formal Methods, Category Theory, University of Calgary brett.gi...@ucalgary.ca ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell] Woes on MacOS 10.6 - linking issues
Hi Folks I seem to have Gtk2HS 0.11 installed, but not quite working. Interestingly, I can run a demo, such as the hello/World.hs example, directly in ghci. However, when I try to do a ghc --make on any code containing gtk2hs I get a link error like this: Undefined symbols: _iconv_close, referenced from: _hs_iconv_close in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_close) _iconv, referenced from: _hs_iconv in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open, _hs_iconv , _hs_iconv_close ) _iconv_open, referenced from: _hs_iconv_open in libHSbase-4.2.0.0.a(iconv.o) (maybe you meant: _hs_iconv_open) ld: symbol(s) not found I do have libiconv installed as a universal library via macports. gtk, glade etc., are also universal installed via macports. I downloaded the OSX Haskell Platform package and am running ghc 6.12.1 Other programs seem to be having some issues as well though, For instance, a command line program seems to compile fine, but when it runs I get the message: $ emlqpl (--- My successfully compiled program - batch only, no gtk items) dyld: Library not loaded: /opt/local/lib/libgtk-quartz-2.0.0.dylib Referenced from: /usr/local/bin/emlqpl Reason: image not found Trace/BPT trap Does anyone have any suggestions? Brett Giles Grad Student, Formal Methods, Category Theory, University of Calgary brett.gi...@ucalgary.ca ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] same type multiply implementing a class
Note the live version of this on haskell wiki is at: http://www.haskell.org/haskellwiki/Wrapper_types The link below is for the old non-editible version of the haskel wiki. On Thu, 2007-03-15 at 15:34 -0600, Derek Elkins wrote: Wolfgang Jeltsch wrote: Am Donnerstag, 15. März 2007 03:23 schrieb Daniel Mahler: Is there any way for the same type to implement a typeclass multiple ways. You can wrap the type using newtype, thus creating a new type which can implement type class methods differently. This technique is sometimes known as a typeclass wrapper and is related to wrapper types and combines well with phantom types. See http://www.haskell.org/hawiki/WrapperTypes ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] HaWiki closing in one month; migrate content to HaskellWiki now!
For those of you busy moving the changes over, you may want to check out the new Haskell wiki guidelines at http://haskell.org/haskellwiki/HaskellWiki:Guidelines as there are some differences with the old HaWiki (especially in page naming :) Also the editing help at http://haskell.org/haskellwiki/Help:Editing contains a summary of some of the formatting differences between the old and new wiki's. Hi all, HaWiki[1] has been deprecated since the beginning of this year[2] when the new HaskellWiki[3] was introduced. However, we are now in the situation where we have both wikis running in parallel, which occasionally causes confusion to users, and means we have outdated information lying around on the old wiki. We have therefore decided that the old wiki will be taken down at the end of this month. If there is any information on it that you think should be kept but has not yet been migrated to the new wiki, this is the time to act! We have made a page for handling the migration, listing all the pages on the old wiki: http://www.haskell.org/haskellwiki/HaWiki_migration If you migrate a page, or find that it has already been migrated, then remove it from the list. Remember you need to check licences before moving content to the new wiki! Thanks Ian and Shae [1] http://www.haskell.org/hawiki/ [2] http://www.haskell.org/pipermail/haskell/2006-January/017287.html [3] http://www.haskell.org/haskellwiki/Haskell Brett Giles Grad Student, Formal Methods UofC http://pages.cpsc.ucalgary.ca/~gilesb http://haskell.org/haskellwiki/User:BrettGiles ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Who brought the monad to us?
Hi Wolfgang You may want to consider the papers by E. Moggi on Monadic computation (1989, 1990) at http://www.disi.unige.it/person/MoggiE/publications.html and Andrew Gordon's thesis Functional Programming and Input/Output (Sorry, I don't have a URL). Brett Giles [EMAIL PROTECTED] http://pages.cpsc.ucalgary.ca/~gilesb On Mon, 2005-08-29 at 18:20 +0200, Wolfgang Jeltsch wrote: Hello, is it right to say that Philip Wadler was the one who invented monadic I/O or were there others who did so together with Wadler? I need this for my thesis. :-) Best wishes, Wolfgang ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Compiler 5.02 asked me to report a bug.
Hi, While using green-card to create an interface for postgres database
access, I recieved the following when I executed
ghc -c PG.hs -o PG.o -fglasgow-exts -i/usr/local/gc-2.03/lib/ghc
-package text -package data -package util
ghc-5.02: panic! (the `impossible' happened, GHC version 5.02):
Native code generator can't handle foreign call
{-_ccall-}__casm ``do {PGresult * t;int result;
t = (PGresult *)%0;
do { result = PQnfields( t );
%r = (int)(result);} while(0);} while(0);''
Please report it as a compiler bug to [EMAIL PROTECTED],
or http://sourceforge.net/projects/ghc/.
I am using a newly compiled version of green-card (2.03) on Debian
testing. This is interfacing to postgres version 7.1.3, standard Debian
install.
The ghc is the standard Debian testing install asl well.
I have attached the PG.gc ,hs and .hi files, as well as an optional
include file used for hugs...
Please note, this interface has been working for hugs (albeit with problems)
Please let me know if there is anything I can do to assist in further
debugging.
Brett Giles
Grad Student in formal methods, University of Calgary,
http://www.cpsc.ucalgary.ca/~gilesb
module PG where
-- (
--{-type-} PGConn,
--connect, quickConnect, disConnect,
--host, port, user, tty, dbName, options, query,
--{-type-} PGResult, PGResEmpty, PGResOk, PGResCOut, PGResCIn,
-- PGResBad, PGResError, PGResTuples,
-- {-type-} PGTuples,
--nFields, nTuples, fld2Inx, inx2Fld, getVal, getValNamed,
--fields, row, col, colNamed, values
-- )
-- where
import StdDIS
-- encapsulate the foreign objects ( C pointers )
newtype PGConn = PGC ForeignObj-- a connection
newtype PGTuples= PGT ForeignObj-- result tuples
instance Eq PGTuples where
_ == _= False
instance Show PGTuples where
showsPrec _ _ = showString TUPLES
data PGResult = PGResEmpty
| PGResOk
| PGResCOut
| PGResCIn
| PGResTuples PGTuples
| PGResBad String
| PGResError String
deriving Eq
instance Show PGResult where
showsPrec _ PGResEmpty= showString PGRES: empty query
showsPrec _ PGResOk = showString PGRES: query ok
showsPrec _ PGResCOut = showString PGRES: copy out started
showsPrec _ PGResCIn = showString PGRES: copy in started
showsPrec _ (PGResBad s) = showString ( PGRES: ++ s ++ )
showsPrec _ (PGResError s)= showString ( PGRES: ++ s ++ )
showsPrec _ (PGResTuples t) = showString (show t)
-- BEGINNING of GreenCard code -
%#include hskPG.h
%dis pgconn pgc = PGC (declare {PGconn *} pgc in (foreign pgc {PQfinish}))
%dis pgtuples pgt = PGT (declare {PGresult *} pgt in (foreign pgt {freePGRes}))
%fun primCmpTuples :: PGTuples - PGTuples - Bool
%call (pgtuples a) (pgtuples b)
%code res = 1;
%result (bool res)
%fun connect :: String - String - String - String - String - String -
%String - IO PGConn
%call (string pghost) (string pgport) (string pgoptions) (string pgtty)
% (string dbName) (string login) (string pwd)
%code ConnStatusType status;
% res = PQsetdbLogin ( pghost, pgport, pgoptions,
% pgtty, dbName, login, pwd );
% status = PQstatus( res );
% if ( status == CONNECTION_BAD ) PQfinish( res );
%fail { status == CONNECTION_BAD } { PQerrorMessage( res ) }
%result (pgconn res)
%fun disConnect :: PGConn - IO ()
%call (pgconn conn)
%code PQfinish (conn);
%fun quickConnect :: String - String - String - IO PGConn
%call (string pghost) (string pgport) (string dbName)
%code ConnStatusType status;
% res = PQsetdbLogin ( pghost, pgport, NULL, NULL, dbName, NULL, NULL );
% status = PQstatus( res );
% if ( status == CONNECTION_BAD ) PQfinish( res );
%fail { status == CONNECTION_BAD } { PQerrorMessage( res ) }
%result (pgconn res)
%fun host :: PGConn - String
%call (pgconn conn)
%code res = PQhost( conn ); if ( !res ) res = ;
%result (string res)
%fun port :: PGConn - String
%call (pgconn conn)
%code res = PQport( conn ); if ( !res ) res = ;
%result (string res)
%fun user :: PGConn - String
%call (pgconn conn)
%code res = PQuser( conn ); if ( !res ) res = ;
%result (string res)
%fun dbName :: PGConn - String
%call (pgconn conn)
%code res = PQdb( conn ); if ( !res ) res = ;
%result (string res)
%fun tty:: PGConn - String
%call (pgconn conn)
%code res = PQtty( conn ); if ( !res ) res = ;
%result (string res)
%fun options:: PGConn - String
%call (pgconn conn)
%code res = PQoptions( conn ); if ( !res ) res
