It's jarring initially, but becomes natural very quickly. Writing loops like "for i in 1:length(arr) ... end" is pretty neat compared to C++ or even python. Plus in math sequences typically start at index 1.
I would go as far as to say that it is now largely an archaic idiom to write «for i in 1:length(arr) ... end», and there is no reason to write such a code to process a collection of elements (an array, a list etc) in its entirety. Yet, people keep on writing it and then spend countless man-hours chasing subtle bugs that blow out later in production.
Most modern languages have a «foreach» operator or its functional equivalent as a collection item generator. «foreach elem in my_collection {}» also has a clearly defined semantics: «process everything». The code is cleaner, concise and a bit shorter and reduces the cognitive overload. And since many languages now support lambdas, the code can quickly and error free be converted into a staged data processing pipeline without the use of temporary variables that serve no purpose, e.g. «foreach elem in my_collection.filter (_ -> _.my_selection_criteria ("42"); ) { do_something (elem); }». Whether the collection is indexed from 0 or from 1 becomes irrelevant.
You should never write loops that way, at least in code you're going to share (assuming that you’re going to have some arr[i] in the loop body—if not, you would just do "for e in arr").
Assuming that arrays start at 1 is a source of occasional bugs in public packages. The existence of OffsetArrays means that arrays can start at any index (so for people who get nauseated by 1-based arrays, you can change it).
Instead, write "for i in eachindex(arr)".
In fact, Julia’s array syntax means you can loop over and manipulate arrays without using indexes much of the time, so don’t even need to know how they’re based.
> Plus in math sequences typically start at index 1.
I'm not quite sure that this is the case enough to say "typically". In terms of undergraduate exposure to math, I think more people have taken Calculus (or Analysis) than Linear Algebra, and I think Calculus textbooks tend to index from 0 while Linear Algebra textbooks tend to index from 1.
