From: Santoemma E. <enr...@be...> - 2005-02-04 13:20:31
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Thank you, Bjorn. I'll test it. The bug list isn't discouraging :) Btw, is it possible that the bug 'Repeated field names don't work' is = due to the fact that one cannot read the same field two times when using = ODBC? This is an old odbc error that I often (still) meet. In haskell I strictly retrieve the record into memory before starting to = retrieve a field, and this fixes the error. It seems that the second read gets an emtpy string. Enrico -----Messaggio originale----- Da: Bjorn Bringert [mailto:d00...@dt...] Inviato: venerd=EC 4 febbraio 2005 13.31 A: Santoemma Enrico Cc: HaskellDB (E-mail) Oggetto: Re: [Haskelldb-users] HaskellDB in an industrial environment Santoemma Enrico wrote: > 1) Is the library too young for a real world project? Does it work > with Oracle (throuhg ODBC)? There are still significant bugs in HaskellDB, see the open bugs in http://sourceforge.net/tracker/?group_id=3D101095&atid=3D629040 Whether it is ready for a real world project depends on the nature of=20 the project I guess. The only way to find out is to test it. I should=20 mention that there is currently no support for things like prepared=20 statements and persistant connections. HaskellDB works with the HSQL and wxHaskell ODBC interfaces, but as far as I know, noone has tested HaskellDB with Oracle. > 2) I'm happy to test the library, but in case of big troubles/doubts > is it realistic to get feedback from the people behind the software > in, say, 2-3 days? At the moment, I seem to be the only person answering questions, and I can't promise to always be available because of travel and such. I am also quite bust right now, so I don't have much time for large scale hacking. I should have time for small fixes, applying patches and answering questions though. > 3) Where exactly the correction to the DBDirect bug is? The home page > says that, on Oct 3, there is a bug fixed in cvs. I downloaded > DBDirect v. 1.12 but I found only minor changes on the error strings. As far as I recall, the fix was not in the DBDirect module itself, but rather in one of the modules it uses. In general, using the CVS version is probably the best way to go, since there hasn't been a release for a while. /Bj=F6rn Bringert |
From: Bjorn B. <d00...@dt...> - 2005-02-04 14:07:52
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Santoemma Enrico wrote: > Btw, is it possible that the bug 'Repeated field names don't work' is > due to the fact that one cannot read the same field two times when > using ODBC? This is an old odbc error that I often (still) meet. In > haskell I strictly retrieve the record into memory before starting to > retrieve a field, and this fixes the error. The problem is that the extensible record type that we created for=20 HaskellDB does not disallow creating a record which contains two fields=20 with the same label. HList, presented at Haskell Workshp 2004 has a=20 solution to this problem, see http://homepages.cwi.nl/~ralf/HList/paper.p= df /Bj=F6rn |
From: Jeremy S. <jer...@li...> - 2005-02-04 17:19:57
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At Fri, 04 Feb 2005 15:08:24 +0100, Bjorn Bringert wrote: > > Santoemma Enrico wrote: > > Btw, is it possible that the bug 'Repeated field names don't work' is > > due to the fact that one cannot read the same field two times when > > using ODBC? This is an old odbc error that I often (still) meet. In > > haskell I strictly retrieve the record into memory before starting to > > retrieve a field, and this fixes the error. > > The problem is that the extensible record type that we created for > HaskellDB does not disallow creating a record which contains two fields > with the same label. HList, presented at Haskell Workshp 2004 has a > solution to this problem, see http://homepages.cwi.nl/~ralf/HList/paper.pdf Speaking of which, do you think that we should try to convert haskelldb to something like the scheme presented in the Hlist paper? I am not familiar enough with the internals of haskelldb yet to compare the existing scheme to the one proposed in hlist... Jeremy Shaw. -- This message contains information which may be confidential and privileged. Unless you are the addressee (or authorized to receive for the addressee), you may not use, copy or disclose to anyone the message or any information contained in the message. If you have received the message in error, please advise the sender and delete the message. Thank you. |
From: Bjorn B. <bri...@cs...> - 2005-02-05 20:34:29
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Jeremy Shaw wrote: > Bjorn Bringert wrote: >>Santoemma Enrico wrote: >>>Btw, is it possible that the bug 'Repeated field names don't work' is >>>due to the fact that one cannot read the same field two times when >>>using ODBC? This is an old odbc error that I often (still) meet. In >>>haskell I strictly retrieve the record into memory before starting to >>>retrieve a field, and this fixes the error. >> >>The problem is that the extensible record type that we created for=20 >>HaskellDB does not disallow creating a record which contains two fields= =20 >>with the same label. HList, presented at Haskell Workshp 2004 has a=20 >>solution to this problem, see http://homepages.cwi.nl/~ralf/HList/paper= .pdf >=20 > Speaking of which, do you think that we should try to convert > haskelldb to something like the scheme presented in the Hlist paper? I > am not familiar enough with the internals of haskelldb yet to compare > the existing scheme to the one proposed in hlist... I know the HaskellDB version well, but I haven't studied HList well=20 enough to to be sure. I guess it would be ideal if we could use HList as=20 a library, but I don't know if this is feasible. /Bj=F6rn |