> 'collect' has a different syntax. Following 'usr' and '+Pat', it expects
> a "from" and a "till" value (the "till" is optional), and then a chain
> of 'get' arguments to retrieve subsequent values from the results.
> For example (in the "app/" demo):
> : (collect 'nr '+Item NIL T 'sup 'nm)
> -> ("Active Parts Inc." "Seven Oaks Ltd." ...)
> This collects all items (from NIL till T), then retrieves the supplier
> from each item, and then the name from each supplier.
> What you probably intended was
> : (filter '((This) (= *D (: doc))) (collect 'usr '+Pat *U))
Yes, that's what I wanted. I thought it was possible to avoid
collecting the whole list constraining the search space before
collecting the values.