Re: [Ocaml-lib-devel] Re: De-functor-ized Psqueue

[Brian H. <bri...@ql...>]

On Thu, 29 May 2003, Alan Post wrote:

> > let iter f e =
> >     let c = e.count() in
> >     for i = 1 to c do
> >         f (e.next())
> >     done
> > 
> This undoes the lazy nature of Enum.filter, Enum.filter_map, and even
> more seriously, input_enum and input_char_enum.  Basically, anywhere
> the code uses Enum.from will be a problem when relying on Enum.count.
> 

This doesn't change the lazy nature of map- map remains the same.  Calling 
count on the result of Enum.from does force the entire enumeration into 
memory- granted.  Which is why I thought of the has_next() idea.  Which 
means we only need to be one element ahead ever.

Personally, I'd also like a way for count to be able to say "I don't know 
how many elements are in the enumeration".  But I got shot down on that 
last time around.

Brian