discuss.visual-prolog.com

Posted: **11 Sep 2013 16:28**

Hello Thomas, hi all,

when I create a new "console application"-project (in VIP 7.4 build 7402) and put following code to main.pro

Code: Select all

interface grammar{@Terminal}
 
    domains
        parseTree = parseTree(
            symbol Nonterminal,
            argumentParseTree* ArgParseTreeList).
        argumentParseTree =
            argParseTree(parseTree);
            argTerminal(@Terminal).
 
end interface grammar
 
%------------
 
implement main
 
    open grammar{string}
 
clauses
    run():-
        console::init(),
        ParseTree = parseTree("verum", [argTerminal("true")]),
        stdIo::write(ParseTree).
 
end implement main
 
goal
    mainExe::run(main::run).

then the call to stdIo::write/0... throws an access violation. Probably it's a bug?

Many regards,
Martin

Posted: **11 Sep 2013 18:07**

Yes, that is a bug. We will look at it.

A work around could be to use an ordinary polymorphic domain instead:

Code: Select all

interface grammar{@Terminal}
 
domains
    parseTree{T} = parseTree(
        symbol Nonterminal,
        argumentParseTree{T}* ArgParseTreeList).
    argumentParseTree{T} =
        argParseTree(parseTree{T});
        argTerminal(T).
 
predicates
    printGrammar : (parseTree{@Terminal} Grammar).
 
end interface grammar

I.e. the domain uses a normal type parameter, but in the predicate declaration(s) you will instantiate the domain with the interface parameter (i.e. @Terminal).

Posted: **12 Sep 2013 17:22**

Maybe the origin of the problem is not in stdIo::write/0..., because with my type declaration (not with your work around) the compiler complaines about type incompatibility in

Code: Select all

        ParseTree = parseTree("verum", [argTerminal("true")]),
        _ = toBoolean(ParseTree = ParseTree).

Posted: **13 Sep 2013 8:18**

discuss.visual-prolog.com

Crash in stdIo::write/0...

Crash in stdIo::write/0...