Yes 1-based indexing is a mistake. It leads to significantly less elegant code - especially for generic code - and is no harder to understand than 1-based indexing for people capable of programming. Fight me.
Some would argue that 0-based indexing is significantly less elegant for numerical/scientific code, but that depends on whether they come from a MATLAB/Fortran or Python/C(++) background.
A decision was made to target the MATLAB/Fortran (and unhappy? Python/C++) crowd first, thus the choice of 1-based indexing and column-major order, but at the end of the day it's a matter of personal preference.
0-based indexing would have made it easier to reach a larger audience, however.
> and is no harder to understand than 1-based indexing for people capable of programming.
The same could be said the other way around ;-)
It really isn't. "Scientific code" isn't some separate thing.
The only way it can help is if you're trying to write code that matches equations in a paper that uses 1-based indexing. But that very minor advantage doesn't outweigh the disadvantages by a wide margin. Lean doesn't make this silly mistake.
> If you really need the first or last element
What if you need the Nth block of M elements? The number of times I've written arr[(n-1)m+1:nm] in MATLAB... I do not know how anyone can prefer that nonsense to e.g. nm..<(n+1)m
arr[n..=m]
> arr[1:m] and arr[(m+1):end]
arr[0..m], arr[m..]
Much nicer.
> Arrays are (conceptually) not pointer arithmetic.
Look at a ruler. Does it start at 1?
Yes, of course distances are measured starting from 0. But we count discrete things starting at 1. You can do mental gymnastics to enumerate from zero and many programmers are (unfortunately IMO) taught to do so. It's a hard thing to learn that way, so for the folks that have done so, it often becomes a point of pride and a shibboleth.
As a classic example, a four story building has four floors. But you only need to go up three flights to get to the top. You can legitimately call the top floor either 3 or 4, and folks are similarly tribal about their own cultural norms around this one, too.
No I disagree entirely. One is simply better.
> It's a hard thing to learn that way, so for the folks that have done so, it often becomes a point of pride and a shibboleth.
It is not hard. It's not better because it's hard-won knowledge. It's better because it leads to simpler, more elegant code. Simple as.
so you just need to overload the syntax of intervals even more to make it work
> arr[0..m], arr[m..]
now `m` refers to different things depending on which side of the interval it's on. less characters doesn't mean nicer
I get it though, I was skeptical about 1-based indexing when I started Julia. By the nature of indices vs length there will always be an off-by-one problem: either you have elements [n, m - 1] with length (m - n) or [n, m] with length (m - n + 1). Unless you're doing a bunch of pointer arithmetic type stuff, I find the symmetry of a inclusive-inclusive interval to be a better default.
As a final rebuttal I offer: range(n - 1, -1, -1)
As a neat bonus, in Julia 1:5 is just the iterator for the numbers 1 to 5. So slicing is typically not some special syntax either. It all works rather nicely.
Which is more natural? The ruler is exactly the right mental image if an array to you is a partitioned region of memory starting at a specific pointer location. If an array to you is an ordered collection of objects, you would never invent 0-based indexing or inclusive-exclusive slicing.
Either way, it's not a big deal. I have lived in both worlds, I have come to think Julia is a bit more natural and easier to teach. But it ls really the silliest bike shedding complaint, given that the language has considerable real trade offs.
They way people reveal themselves is a pattern worthy of taking note.
I find it to be substantially worse. It's fine as long as you don't manipulate the indicies. But as soon as you start doing math on them 1 based becomes a headache (at least IME).
Meanwhile all you get in exchange (at least as far as I can tell) is ease of speaking about them in natural language. But I'm not usually conversing about indicies.
Concise range notations are a mixed bag. There's pros and cons to either scheme there as far as the syntax goes.
I don't think one is better than the other but my mind is currently wired to see indexing with base 1.
Then there's Option Base 1 in VBA if you don't like the default behavior. Perfect for creating subtle off-by-one bugs.
The real indexing issue is whether arbitrary-base abstraction is too easily available.
# Correct, Vector is 1-based
function mysum(v::Vector{T}) where {T <: Integer}
s = zero(T)
for i in 1:length(v)
s += v[i]
end
return s
end
#Incorrect, AbstractVector is not necessarily one based
function mysum(v::AbstractVector{T}) where {T <: Integer)
s = zero(T)
for i in 1:length(v)
s += v[i]
end
return s
end
#Correct
function mysum(v::AbstractVector{T}) where {T <: Integer)
s = zero(T)
for e in v
s += e
end
return s
end
Recently we got the public keyword, but even the PR there says:
"NOTE: This PR is not a complete solution to the "public interfaces are typically not well specified in Julia" problem. We would need to implement much than this to get to that point. Work on that problem is ongoing in Base and packages and contributions are welcome."