Re: [Ocaml-lib-devel] ExtArray?

[Amit D. <ami...@gm...>]

On 11/24/05, Richard Jones <ri...@an...> wrote:

> > (1) What is the point of having two rev functions?  Arrays are indexed,
> you
> > can just access n-i instead of i.
>
> I'm not sure if the objection is to having 'Array.rev*' altogether or
> having two different versions of this function.  Well, the point of
> having 'Array.rev' is simply because there is a 'List.rev'.  'Array.-
> rev_in_place' is an extension to the standard set of common functions
> which only applies to the special case of arrays because arrays are
> mutable.


Both ;)  But, I see some other languages seem to have library functions for
in place reversal.  Still, though, I'm unconvinced that there should be a
copying reversal function.  In the C++ STL, they defined interface function=
s
to be general across container types.  List doesn't have this property: it
was designed to be an interface for List alone.  And List is an immutable
container type.  So, I think we should be careful about duping the behaviou=
r
of List here.

> (2) find_all should return a list.  e.g. find_all in ExtHashtbl returns a
> > list.
>
> OK, but conversely List.find_all is defined as identical to
> List.filter.  Hashtbl.find_all is quite a different function.  It
> returns all values associated with a single key, and only makes sense
> because of a peculiarity of Hashtbl, namely that one can associate
> multiple values with a key.


True.  But I already stated another, probably more important reason above:
filter suggests it returns the same container type as it was given.
find_all doesn't suggest this at all.  They are the same in list only
because (barring enums) the only sensible return type for find_all is a
list.

Maybe we should change the documentation of ExtList.find_all to make this
clear.  i.e. say, find_all returns a list containing matching elements, in
the case lists, it is equivalent to filter.

-Amit