[m-rev.] for review: string.between

[Mark Brown]

Hi,

On 10-Jun-2011, Peter Wang <novalazy at gmail.com> wrote:
> Branches: main
> 
> Deprecate string.substring, string.foldl_substring, etc. in favour of
> new procedures named string.between, string.foldl_between, etc.
> The "between" procedures take a pair of [Start, End) endpoints instead
> of Start, Count arguments.  The reasons for this change are:
> 
> - the "between" procedures are more convenient
> 
> - "between" should be unambiguous.  You can guess that it takes an End
>   argument instead of a Count argument without looking up the manual.
> 
> - Count arguments necessarily counted code units, but when working with
>   non-ASCII strings, almost the only way that the values would be arrived at
>   is by substracting one end point from another. 
> 
> - it paves the way for a potential change to replace string offsets with an
>   abstract type.  We cannot do that if users regularly have to perform a
>   subtraction between two offsets.

I agree with reasons 1, 3 and 4.  This is the right interface, IMO.

I haven't looked at the code; I assume it's straightforward.

Cheers,
Mark.

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