Search found 76 matches

by Chris Walton
Wed Aug 07, 2013 10:15 am
Forum: Language Issues
Topic: Type inheritance constraint syntax query
Replies: 6
Views: 10892

Type inheritance constraint syntax query

Given: TYPE P POSSREP { VALUE CHAR } ; VAR S BASE RELATION { X1 P, X2 INT } KEY { X2 } ; S := RELATION { TUPLE { X1 P ( "T1" ), X2 INTEGER ( 1 ) }, TUPLE { X1 P ( "T2" ), X2 INTEGER ( 2 ) } }; What syntax defines TYPE Q IS { P CONSTRAINT **see below** POSSREP { VALUE = THE_VALUE ...
by Chris Walton
Tue Jul 30, 2013 8:00 pm
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

REL Crashing

I have identified the minimum elements needed to reproduce this problem: Define the following items in this order: OPERATOR LENGTH(s CHAR) RETURNS INTEGER Java FOREIGN return ValueInteger.select(context.getGenerator(), s.stringValue().length()); END OPERATOR; TYPE BDT_symbolic POSSREP { VALUE CHAR }...
by Chris Walton
Tue Jul 30, 2013 7:31 pm
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

Re: Disabled DBrowser

It may be worth mentioning that what set me off on these wild goose chases are automatic bug reports generated by Rel. These are IDs 18-20. Whatever is causing these crashes is still an ongoing problem. Cheers Chris
by Chris Walton
Tue Jul 30, 2013 3:33 pm
Forum: Language Issues
Topic: TYPE inheritance implications
Replies: 6
Views: 16988

TYPE inheritance implications

Given a type definition TYPE A POSSREP { VALUE CHAR } ; which generates the following operators A ( CHARACTER ) RETURNS A IS_A ( A ) RETURNS BOOLEAN THE_VALUE ( A ) RETURNS CHARACTER TREAT_AS_A ( A ) RETURNS A and the type definition TYPE B IS { A CONSTRAINT ( TRUE ) POSSREP { VALUE = THE_VALUE ( A ...
by Chris Walton
Tue Jul 30, 2013 3:22 pm
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

Re: Disabled DBrowser

Thank you - sorted - I needed to add \bin to my JDK_HOME.
by Chris Walton
Mon Jul 29, 2013 5:10 pm
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

Re: Disabled DBrowser

I spoke too soon. Rel now opens and runs, but trying to define one of the operators from your scripts provides the following error: ERROR: ca.mb.armchair.rel3.exceptions.ExceptionSemantic: java.io.IOException: Cannot run program "javac": CreateProcess error=2, The system cannot find the fi...
by Chris Walton
Mon Jul 29, 2013 4:47 pm
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

Re: Disabled DBrowser

Thanks - that was the problem. Of course by the time I got your email I had re-downloaded Java and Rel; uninstalled jdk/jre/rel; done a complete backup of my system; cleaned the registry extensively; donea clean install of jdk/jre/rel; and tried again with Rel. Oh well - it's all character building ...
by Chris Walton
Sun Jul 28, 2013 2:05 am
Forum: Report a Bug
Topic: Disabled DBrowser
Replies: 11
Views: 612949

Disabled DBrowser

After the crash (a report of which was sent automatically to you some hours ago (ID 50/80 ?)), it is now impossible to run DBrowser. I continually get the message: java.io.IOException: Cannot run program "C:\Program": CreateProcess error=2, The system cannot find the file specified I have ...
by Chris Walton
Sat Jul 27, 2013 9:08 pm
Forum: Rel Examples
Topic: Example 6: Dyadic OPERATOR on Relvar
Replies: 0
Views: 21011

Example 6: Dyadic OPERATOR on Relvar

Dyadic OPERATOR on Relvar

Code: Select all

OPERATOR equals ( P TUPLE { name data_type } , Q TUPLE { name data_type} ) RETURNS boolean ;
  if P = Q then return true;
  else return false; 
  end if ;
END OPERATOR ;
by Chris Walton
Sat Jul 27, 2013 9:06 pm
Forum: Rel Examples
Topic: Ex5: Monadic OPERATOR on TUPLE
Replies: 0
Views: 20972

Ex5: Monadic OPERATOR on TUPLE

Simple monadic OPERATOR on TUPLE

Code: Select all

OPERATOR no_op ( P TUPLE { name data_type_type_symbolic } ) ; 
END OPERATOR ;
by Chris Walton
Sat Jul 27, 2013 9:02 pm
Forum: Rel Examples
Topic: Ex1: TYPE definitions
Replies: 1
Views: 8257

Ex1: TYPE definitions

Simplest type TYPE data_type POSSREP { value CHAR }; Inheritance from built-in type TYPE Ntest2 IS { INTEGER  CONSTRAINT INTEGER < 10 }; Union type TYPE data_type UNION; Union type with own possrep TYPE data_type UNION POSSREP { domain ID, name ID, T ID }; Specialisation by constraint TYPE art IS {...
by Chris Walton
Sat Jul 27, 2013 9:01 pm
Forum: Rel Examples
Topic: Candidate examples
Replies: 2
Views: 8782

Re: Candidate examples

A long time down the line, I am finally in a position to start posting candidate examples. This first batch is VERY elementary, but reflects points where I have encountered difficulty in getting syntax and concepts understood. The format I have chosen is to post each example as a new topic, and form...
by Chris Walton
Sun Oct 07, 2012 9:13 pm
Forum: Language Issues
Topic: getoperatorreturntyp
Replies: 1
Views: 6804

getoperatorreturntyp

The non-terminal getoperatorreturntype is defined in the grammar, but is never used. Is this in respect of work in development?
by Chris Walton
Fri Aug 31, 2012 5:56 am
Forum: Rel Examples
Topic: Candidate examples
Replies: 2
Views: 8782

Candidate examples

I am using Rel to learn about the language, and the application of pure relational concepts rather than the variant embedded in SQL. I am also using a subset of Rel as part of a definition language I am writing. I am deriving many Rel fragments code as I do so. Would there be any value in posting so...
by Chris Walton
Fri Aug 24, 2012 3:46 pm
Forum: Language Issues
Topic: Relvar syntax definition
Replies: 2
Views: 8243

Re: Relvar syntax definition

Thanks for the explanation. I believe there is an English saying - there's none so blind as those who will not see. I could not see for looking.