ocaml-lib-devel

[Ocaml-lib-devel] Hashtbl.length and Hashtbl.size

[Martin J. <mar...@em...>]

Hi,

I am sometimes missing a function that returns the size of a hash table:
1. length of the underlying array
2. number of elements.

let length tbl = Array.length tbl.data
let size tbl = tbl.size

The purpose of the length function is to return a good guess for the size
of a table that we want to fill with more or less the same number of
elements than an existing table.

Did I miss anything?

Martin

Re: [Ocaml-lib-devel] Hashtbl.length and Hashtbl.size

[Nicolas C. <war...@fr...>]

> Hi,
>
> I am sometimes missing a function that returns the size of a hash table:
> 1. length of the underlying array
> 2. number of elements.
>
> let length tbl = Array.length tbl.data
> let size tbl = tbl.size
>
> The purpose of the length function is to return a good guess for the size
> of a table that we want to fill with more or less the same number of
> elements than an existing table.
>
> Did I miss anything?

They are actually useful, and I think we could add them to the ExtHashtbl
module.
However, I'm not sure about the naming : one could mistake size and length.

I propose the following :

"count" for the number of inserted elements (wrt Enum)
"allocated_size" (or something else) for the size of the underlying array.

Regards,
Nicolas Cannasse

Re: [Ocaml-lib-devel] Hashtbl.length and Hashtbl.size

[Martin J. <mar...@em...>]

On Wed, 14 Apr 2004, Nicolas Cannasse wrote:

> I propose the following :
>
> "count" for the number of inserted elements (wrt Enum)
> "allocated_size" (or something else) for the size of the underlying array.

Why not cardinal and array_length?

cardinal vs. count: we don't trigger an iterative algorithm; cardinal is
                    more neutral
array_length: hash tables are always supposed to be based on arrays,
              right?

Martin

Re: [Ocaml-lib-devel] Hashtbl.length and Hashtbl.size

[Nicolas C. <war...@fr...>]

> > I propose the following :
> >
> > "count" for the number of inserted elements (wrt Enum)
> > "allocated_size" (or something else) for the size of the underlying
array.
>
> Why not cardinal and array_length?
>
> cardinal vs. count: we don't trigger an iterative algorithm; cardinal is
>                     more neutral
> array_length: hash tables are always supposed to be based on arrays,
>               right?

let me dismiss "cardinal" : we have already List.length , Enum.count,
IO.available ... users might be confused if we had one more way of counting
: IMHO  "count" and "length" are the only choices, but "length" is more
appropriate for flat data structures such as List or Arrays.

about "array_length" I'm not satisfied either with "allocated_size" nor
"array_length" since the last one is giving information on how hashtbl are
implemented, which is never a good idea in an abstract interface.

Regards,
Nicolas Cannasse

Re: [Ocaml-lib-devel] Hashtbl.length and Hashtbl.size

[Martin J. <mar...@em...>]

On Wed, 14 Apr 2004, Nicolas Cannasse wrote:

> about "array_length" I'm not satisfied either with "allocated_size" nor
> "array_length" since the last one is giving information on how hashtbl are
> implemented, which is never a good idea in an abstract interface.

Hashtbl must provide hash tables or I will not use it anymore. It has to
rely on an array-like structure. So what's wrong?

Martin

[Ocaml-lib-devel] Re: Hashtbl.length and Hashtbl.size

[Alan P. <ap...@re...>]

In article <016201c42242$194dc6d0$ef01a8c0@warp>, Nicolas Cannasse wrote:
> 
> "count" for the number of inserted elements (wrt Enum)
> "allocated_size" (or something else) for the size of the underlying array.

What about "bucket_count" for the number of buckets?