Re: [Ocaml-lib-devel] Proposal for new list functions

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

> I propose the addition of two new functions into ExtList.List module.
> I've found these to be useful in parsing and manipulating token lists.
> I think these might be useful for other people as well.  I'm not sure
> if the naming is good, so feedback is welcome.  There's already a
> function called "split" in the List module, so I guess I need to come
> up with some other name for it.  The name stems from the functions
> similarity to String.split.

> val fold_left_while :
>    ('a -> 'b -> bool) -> ('a -> 'b -> 'a) -> 'a -> 'b list -> 'a = <fun>

I think too that having an exception is better than providing two functions.
In general you want to stop recursion on a case that can't be treated by
your "fold" , so you're already matching into your fold, with maybe an
assert false in the case you already filtered it. It's better then to group
both test+fold into a single function since I can't see good cases when you
want to freely compose different folds and different stoppers.

> The second function is called split.  I've used it to split lists of
> tokens into sublists (such as splitting argument lists by
> COMMA-token).

>> let split : ('a -> bool) -> 'a list -> 'a list list = <fun>

That one might be useful in some cases.
But it needs a new name ;)

Nicolas