Setting function interpretation to constructed from symbol

[fredericg]

How can one refer to a constructed type when trying to interpret a function?

vocabulary voc{
    type Soort constructed from {A, B}
    ProductSoort:Soort
}

include <mx>
procedure main(){
    struc = newstructure(voc, "struc")
    maketrue(struc[voc::ProductSoort].graph, {"B"})
}

Throws:

Error: Element "B" is not part of table 28ConstructedInternalSortTable[A, B], but you are trying to assign it to such a table

[Bart Bogaerts]

struc[voc::B]()

This means: the image of the (constructed) constant B in struc