DES 2.1 Released

[Apologies for multiple receptions]

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

  Datalog Educational System version 2.1 
  http://des.sourceforge.net

has been launched on November, 30th, 2010, and ported to

  GNU Prolog 1.3.1

The main novelty in this release is the ability to access Datalog 
relations from SQL statements. To this end, types and optionally 
column names can be declared for Datalog relations. Types are one 
kind of integrity constraints which can be imposed to the database. 
This release also offers other Datalog (strong) integrity 
constraints: primary key, foreign key, functional dependencies and 
user-defined integrity constraints. As opposed to relational 
database systems, such constraints can be imposed not only on the 
extensional database (facts) but also on the intesional database 
(views). When constraint checking is enabled (it can be enabled or 
disabled with a command), the system monitors such constraints 
whenever a new fact or rule is asserted. As well, given a database, 
asserting an integrity constraint only succeeds if the database is 
consistent w.r.t. such constraint. Detailed error reporting in both 
cases is provided.

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 2.1 of DES (released on November, 30th, 2010)

* Enhancements:
  o Access to Datalog relations from SQL statements. To this end, type declarations are provided to allow both give types and names to relation columns
  o Datalog (strong) integrity constraints: type, primary key, foreign key, functional dependencies and user-defined integrity constraints
  o SQL statements can be directly submitted from the Datalog prompt
  o Revised compilation of SQL views to Datalog rules, avoiding unnecesary intermediate relations
  o Enhanced performance: Built-in operators (is, <, >, ...) do not longer rely on the extension table mechanism, speeding computations up to ten times (cf. fib(1000,X) in fib.dl)
  o Negation can be applied to compound goals
  o Displaying of the number of consulted rules
  o Formatted Datalog syntax errors (error text, file name, line and column) 
  o Updated manual
  o Output from the command /builtins rearranged in a way similar to /help
  o User inputs with trailing blanks after the ending optional dot are now accepted
  o Now, string type constraints limit the length of strings as specified in their declarations (e.g., char(1) does not permit strings of length more than 1). Working but in Ciao Prolog source distribution
  o Consulted Datalog files can contain multi-line remarks enclosed between /* and */ 
  o Reworked shell command. Outtput and error streams are redirected to the window application in MS Windows distros (this applies to GNU Prolog, SICStus Prolog and SWI-Prolog)
  o New commands:
    - /cat Filename Type the contents of Filename. Also, the synonym /type Filename is provided
    - /check Display whether integrity constraint checking is enabled
    - /check [Switch] Enable or disable integrity constraint checking (on or off, resp.)
    - /spy Pred[/Arity] Set a spy point on the given predicate in the host Prolog interpreter (command intended for implementors, not users)
    - /nospyall Remove all Prolog spy points (command intended for implementors, not users)
    - /t Terminate the current DES session without halting the host Prolog system (command intended for implementors, not users)
* Changes:
  o For ODBC connections, the table db_schema, which is automatically created to have access to table and view names, was hiden in SICStus Prolog source version
  o Consulting an incorrect line in a Datalog program does not halt from reading subsequent files, if any
* Fixed bugs:
  o Empty strings were not displayed between single quotes
  o The empty constant ('') was rejected in Datalog rules
  o SICStus Prolog source version failed in retrieving tuples with Datalog queries in ODBC connections 
  o Exiting without closing an ODBC connection raised an exception
  o Duplicated answers containing null values were not removed with duplicates disabled. Bug introduced in version 2.0
  o Character inputs were not displayed during batch processing as, e.g., answering single-character inputs ('y', 'n', ...)
  o Ciao Prolog source distribution displayed incorrect paths when listing contents of directories containing '..'
  o When duplicates were enabled, some recursive rules did not provide answers, as fib(3) in fib.dl
  o Windows application entered a loop when closing the window with the white-crossed red button
  o DES could not be interrupted via Ctrl-C in the Ciao source distribution
  o Bitwise disjunction and conjunction were not correctly parsed