Re: [Ocaml-lib-devel] candidate functions

[Eric C. C. <ec...@cm...>]

On Thu, Feb 27, 2003 at 07:51:43PM +0900, Nicolas Cannasse wrote:
> > (* Generate the range of integers [a; a+1; ...; b] *)
> >
> > val range : int * int -> int list
> 
> would prefer :
> range : int -> int ->  int list
> since it's not causing any overhead due to the tuple allocation ( integer
> are unboxed )

That's a reasonable argument.  I like the suggestion of mathematical
"interval notation" with range (1, 10), but don't feel strongly about it.

> > (* Reverse assoc *)
> > (* can also add rassq, mem_rassoc/rassq, remove_rassoc/rassq if needed *)
> >
> > val rassoc : 'b -> ('a * 'b) list -> 'a
> 
> I reallly don't like theses. The usage of them are far from obvious

My old Lisp habits are showing, I guess.

> > (* String equivalents of Array.fold_left and Array.fold_right *)
> >
> > val string_fold_left : ('a -> char -> 'a) -> 'a -> string -> 'a
> > val string_fold_right : (char -> 'a -> 'a) -> 'a -> string -> 'a

I really think these are useful.  For example:

  let checksum data =
    string_fold_left (fun n c -> (n + Char.code c) mod 256) 0 data

  let explode string =
    string_fold_right (fun c list -> c :: list) [] string

> > (* Convert between strings and lists of chars. *)
> >
> > val explode : string -> char list
> > val implode : char list -> string
> 
> Theses four are interesting, but I don't realy see the need of using Strings
> as char list. Could you tell me about it ?

This is another Lisp influence.  I find it easier to write
"functional" string manipulation with these operators (versus the
Buffer module, which is more efficient for large strings, but also
more imperative and less flexible -- you can't go back and insert data
at the beginning or middle).

Thanks for all the comments.

-- 
Eric C. Cooper          e c c @ c m u . e d u