On Fri, Apr 30, 2010 at 4:33 AM, Rich Hickey <richhic...@gmail.com> wrote:
> On Apr 29, 2010, at 4:21 AM, ataggart wrote:
>> Functions named contains-key? and contains-val? would make a lot more
>> sense to me than the current contains? and new seq-contains?. Anyone
>> looking at contains-val? should expect it to be O(n). The only
>> effective difference would be that the test value for contains-val? is
>> consistently a single value rather than a [key value] tuple for maps.
>
> People don't consider sets, vectors, arrays or strings to have 'keys'. But,
> like maps, they all support fast lookup of some sort.
Actually I do consider sets to have keys, since internally they are
implemented using maps, so the exact same semantics apply for their
lookup. They're just maps where the key and value are the same thing:
protected APersistentSet(IPersistentMap impl){
this.impl = impl;
}
public boolean contains(Object key){
return impl.containsKey(key);
}
public Object get(Object key){
return impl.valAt(key);
}
Because of this I would also expect contains-val? to be constant-time
for sets, so I think seq-contains? is a better name.
Anyway, I'm a little weary of this discussion by now, (and I can't be
the only one) so I'd be perfectly happy leaving things as they are. I
am glad that a lot of thought goes into these names though; it
definitely shows.
-Phil
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