DES 2.2 Released

[fernan]

[Apologies for multiple receptions]

Hello.
This is a mail just for informing that the new release 

  Datalog Educational System version 2.2 
  http://des.sourceforge.net

has been launched on March, 24th, 2011, and ported to

  GNU Prolog 1.3.1

There have been several improvements in this release but not a major 
feature. For instance, a new type inferencing system has been added, 
which now allows users to impose type constraints on intensional 
predicates, not only in extensional ones as in previous version. As 
well, type inference precision has been upgraded by adding constraint 
solving in the inference process. To ease type declarations, a new 
syntax is provided, which coexists with the original. ODBC 
connections have been revisited, upgraded and tested against other 
DBMSs and databases, as Oracle and SQL Server. In particular, access 
to spatial databases has been successful. New ports have been 
provided (replacing the old ones) to SICStus Prolog 4.2.0 and Ciao 
Prolog 1.13.0, which includes a brand new unreleased CLP(FD) library 
and has been tested on Windows 7 (former version 1.10p5 does not 
work on such OS). Help system has been refactorized and commands to 
ask for help on specific topics are provided. Built-in Prolog DCG 
expansion has been replaced with an explicit translation to avoid 
target system differences. 


A complete list of enhancements, changes and fixed bugs is attached to 
the end of this message. 
Please, see http://des.sourceforge.net for details.

  Best regards.


==============================================================
Fernando Saenz Perez
Profesor Titular de Universidad / Associate Professor
Home Page: http://www.fdi.ucm.es/profesor/fernan
Tel: + 34 913947642. Fax: + 34 913947547
Despacho / Office: 435 (4ª planta / 4th floor)
Dept. Ingenieria del Software e Inteligencia Artificial / 
Department of Software Engineering and Artificial Intelligence
Universidad Complutense de Madrid
Facultad de Informatica
C/Profesor Jose Garcia Santesmases, s/n
E - 28040 Madrid. Spain
==============================================================



Version 2.2 of DES (released on March, 24th, 2011)

* Enhancements:
  o Type constraints can be imposed and checked on intensional predicates, not 
only on extensional ones
  o Improved type inference precision
  o Propositional relations can also be typed
  o Datalog type char added
  o Added alternative syntax for Datalog type constraints:
    :- type(pred(col1:type1,...,coln:typen)) and
    :- type(pred(type1,...,coln)) 
  o Added Oracle predefined 'dual' table
  o Added FROM-less SQL SELECT statements
  o Help system refactoring
  o New commands:
    - /help Keyword Display detailed help about command Keyword
    - /apropos Keyword Synonym for /help Keyword
    - /prolog_system Display the underlying Prolog engine version
  o Formatted ODBC error messages
  o From the Datalog input, ALTER, USE and CREATE TABLE SQL statements are also 
automatically sent to the opened ODBC datatabase, if a connection is already 
opened
  o Added warning for undeclared predicates occurring in basic queries  (i.e., 
those predicates which have not been provided with either a defining rule or a 
type declaration)
  o When executing a query in development mode, its compilation is displayed
  o Multi-line remarks are allowed at the system prompt
  o Developer commands are now available in Ciao source distribution
  o New port to Ciao Prolog 1.13.0. Includes unreleased all-new clpfd library. 
This port replaces the old port to version 1.10p5
  o New port to SICStus Prolog 4.2.0, which includes enhanced and fixed ODBC 
library. Former limitations of DES w.r.t. this port are removed
  o In the context of an opened ODBC connection, predicate dependency graph and 
stratification are computed from the relational database schema, instead of 
querying each table and view. Computing the deductive database part does not 
change 
  o More robust handling of ODBC exceptions
  o SIGINT interrupt signal is catched in SWI-Prolog version so that users can 
now interrupt DES (Ctrl-C usual keyboard interrupt)
  o SQL Server ODBC connections tested on spatial databases
  
* Changes:
  o Built-in Prolog DCG expansion replaced with an explicit translation, which 
can now be found in des_dcg.pl. This file is an adaptation of Ciao's 
dcg_expansion.pl. It works with all supported Prolog systems but GNU Prolog 
1.3.1, which does not provide term expansion
  o A singleton anonymous variable denoted by an underscore in listings is 
displayed with an underscore. Up to version 2.1, it was given a name with 
letters, starting with A
  o Instantiation error exceptions coming from code implementing DES are now 
displayed (only useful for DES implementors)
  o Some program simplifications related to equalities have been omitted for 
the sake of type inferencing. This involves different source-to-source 
translations during query evaluation
  o Built-in is/2 is translated into =/2 at compilation-time when its right 
argument is already evaluated
  o Removed input error message from attempting to add types in the context of 
an opened ODBC connection
  
* Fixed bugs:
  o Unsafety was not reported for anonymous variables (as, e.g., asserting the 
rule p(_))
  o Negation involving an aggregate or outer join predicate with atom syntactic 
form was not transformed (e.g., not(count(p,0)))
  o Changing some system flags in no verbose mode displayed an info message
  o Datalog types char(N) and varchar(N) were not parsed
  o Some Datalog queries with duplicates enabled and an opened ODBC connection 
were incomplete in some special cases where rule identifiers collided
  o Log recording upon exceptions repeated previous lines in some keyboard 
inputs
  o Predicate dependency graph and stratification was not computed when closing 
an ODBC connection
  o Some calls to predicates resulting from translating SQL queries involving 
disjunctions were incorrectly built, as in select * from t where a=1 or b=1