[Martin Meyer]

Hello Thomas,

please check this stripped down version of my code. It throws fatal error c098 : Place was not set (in VIP 8 build 801).

Code: Select all

interface someTypes{@Type}
 
domains
    rec = rec(@Type).
 
domains
    valueProvider = (rec*) -> @Type Value.
 
end interface someTypes
 
%======
 
interface objA
end interface objA
 
%---
 
class objA{@Type} : objA
    open someTypes{@Type}
 
constructors
    new : (valueProvider).
 
end class objA
 
%---
 
implement objA{@Type}
 
clauses
    new(_ProvideValue).
 
end implement objA
 
%======
 
interface objB{@Type}
 
domains
    useTypeToPreventWarning = @Type.
 
end interface objB
 
%---
 
class objB{@Type} : objB{@Type}
end class objB
 
%---
 
implement objB{@Type}
    open someTypes{@Type}
 
clauses
    new() :-
        %hasDomain(valueProvider, ProvideValue),
        ProvideValue = { (RecList) = Val :- [rec(Val)] == RecList },
        _ObjA = objA::new(ProvideValue).
 
end implement objB
 
%======
 
implement main
 
clauses
    run() :-
        _ObjB = objB::new().
 
end implement main

When uncommenting the hasDomain line, the message changes to error c504 : The expression has type '(someTypes::rec*) -> @Type procedure', which is incompatible with the type '(someTypes::rec{@Type}*) -> @Type procedure'. Trying to strip down the problem further, I found that following short code produces same kind of error.

Code: Select all

interface someTypes{@Type}
 
domains
    rec = rec(@Type).
 
end interface someTypes
 
implement main
 
clauses
    run() :-
        hasDomain(someTypes{unsigned}::rec, _Rec).
 
end implement main

[Thomas Linder Puls]

Thank you. We will investigate the problems.

As always I believe you can work around the problems by refraining from using @Type in domains and define ordinary parameterized domains instead. And then only use @Type in predicate declarations.

Code: Select all

interface someTypes{@Type}
 
domains
    rec{T} = rec(T). % Do not use @Type here
 
domains
    valueProvider{T} = (rec{T}*) -> T Value. % Do not use @Type here
 
predicates
    ppp : (valueProvider{@Type} VP). % Here @Type can be used
 
end interface someTypes

The problem is that the domains does not really belong to the objects and therefore it is "problematic" to let them depend on the interface parameters.

But we have allowed such usage, so we will of course address the problem.

[Thomas Linder Puls]

This problem is solved in Visual Prolog 8 - Build 802.