On 13 May 2013 11:21, Florian Weimer <fweimer@redhat.com> wrote:
On 04/18/2013 01:08 AM, Björn Persson wrote:
Florian Weimer wrote:
Yes, Ada has some nice features.  At least there are real arrays, but
they are somewhat cumbersome to work with, compared to Java, Python or,
well, C pointers.  There are two aspects: preservation of array bounds
in slices (so that you have to write Table (Table'First + Offset) to
access the element Offset of Table, Offset ranging from 0 to
Table'Length - 1)

That array bounds must be preserved becomes obvious when you consider
arrays where the index type has a meaning beyond just position in the
array. If you have an array Week with a range of Monday..Sunday, and
you take the slice Week(Saturday..Sunday) and call it Weekend, then you
really don't want Weekend to suddenly have the indexes Monday and
Tuesday.

Weekdays are a very bad example because it is locale-dependent whether Monday < Sunday or the other way round.  So you really can't fit them well into an enumeration type, and Java 8 orders the enumeration values alphabetically by their name, to make that point perfectly clear.


I suppose a week actually looks like a ring buffer rather than a linear array.  Week(Saturday..Sunday) would make sense in that context, but it'd take someone more familiar with esoteric languages than me to say whether there's any language that provides that (not a feature much in demand I'd think).

--
imalone
http://ibmalone.blogspot.co.uk