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- Subject: Re: Selenophobia
- From: Ahmed Charles <acharles@...>
- Date: Tue, 28 Mar 2017 06:11:08 +0000
On 3/25/2017 1:57 PM, Tim Hill wrote:
>> On Mar 25, 2017, at 3:53 AM, Joseph Manning <email@example.com> wrote:
>> On 2017-Mar-25 (Sat) at 12:42 (+0200), steve donovan wrote:
>> Yes! In fact, 1-based indexing is one of the ( several ) reasons
>> that I like Lua. I detest either using, or teaching, the unnatural
>> "0 to length-1" pattern of many other "high-level"(?) languages.
>> But you're right -- "each to their own". 0 versus 1 debates are
>> similar to emacs versus vi debates :-)
> To my mind both have their place. 0-based indexing makes perfect sense in C, where indexing is little more than syntactic sugar over pointer+offset anyway — but really that’s because C was designed (to my mind) as a reified assembly language anyway. However, once you get into higher abstractions (such as any decent script language) 0-based ceases to have much validity imho.
I usually prefer to not debate 0 vs 1 based indexing but I also think
that believing 0 based indexing ceases to make sense for higher level
languages is ignoring important mathematical properties of programming
In this case, it's the fact that a sequence of N things has N+1
positions, at the beginning of each element and just past the last
element. This allows the use of open ended ranges, meaning [a, b), where
a is in the range and b is not. This allows specifying the empty range.
All ranges in Lua are [a, b] and therefore, specifying the empty range
is either impossible or requires using [a, a-1], which most functions
don't specify as being well-formed.
So, yes, if all you ever need is iteration over a sequence, then it
doesn't matter what base is used. But when ranges (including empty ones)
are desired, the natural affinity between 0-based indexing and open
ended ranges does make things easier without lots of special cases.