Hi,
Just playing with Oz, discovering features.
I find it desirable for the case statement to capture not only the
values of fields, but also features and labels as well. As of now, case
declares only identifiers that stand in the field-value position.
Thus the following
declare
X = l(f:1)
case X of l(f:V) then {Browse V} end
displays 1, but the following
declare
X = l(f:1)
case X of l(F:V) then {Browse F#V} end
complains about unintroduced variable F.
I'd prefer the pattern to match a record with one field, any feature.
But ok. Now, the scary thing is when the following is fed:
declare
X = l(f:1)
local F in
case X of l(F:V) then {Browse F#V} end
end
where F is clearly introduced, but unbound, and the interpreter crashes
with lots of curses (Mozart 1.3.2, Fedora).
In general, it would be fine if case could match patterns like
L(...) --- a record with any label and any number of fields
l(F:V ...) --- a record with a specific label, at least one field, the
first field (where fields are sorted according tot he lexicographical
order of the features, as in the arity of a record) having any feature
and any value
l(F:v) --- a record with a specific label, and one field with a specific
value
etc.
Otherwise, one has to use, e.g., Record.label and Record.arity to get at
the label and features of a record one does not know.
vQ
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