[btilly]

Because changing the base is a great source of bugs.

That said, not all languages have given up on this. For example Julia allows it. https://docs.julialang.org/en/v1/devdocs/offset-arrays/

Ironically I learned this from a discussion of Julia bugs. Apparently changing offsetting of arrays has proven to be a source of bugs in Julia. So maybe someday they will come to the same conclusion as languages like Perl and stop allowing it.

[wizofaus]

I'd argue 0-base is a source of bugs too! Ideally we'd be able to catch more array indexing bugs at compile time - there are definitely cases where it should be possible to determine that arrays are being incorrectly indexed via static analysis.

[btilly]

The problem is that libraries which assume 0-base break when you have a 1-based array. And vice versa. Trying to combine libraries with different conventions becomes impossible.

Therefore changing the base leads to more bugs than either base alone.

That said, the more you can just use a foreach to not worry about the index at all, the better.

Of 0-based and 1-based, the only data point I have is a side comment of Dijkstra's that the language Mesa allowed both, and found that 0-based arrays lead to the fewest bugs in practice. I'd love better data on that, but this is a good reason to prefer 0-based.

That said, I can work with either. But Python uses 0-based and plpgsql uses 1-based. Switching back and forth gets..annoying.

[wizofaus]

I'd expect the compiler not to let you to pass a 0-based array to a library function expecting a 1-based array. I'm pretty sure that's how it worked with Visual Basic, which was the only language I ever used such a feature in.

[btilly]

You are demanding a lot from the type system.

Search for OffsetArrays in https://yuri.is/not-julia/ for practical problems encountered in trying to make this feature work in a language whose compiler does try to be smart.

[ChrisRackauckas]

The type system does tell you if this is used. `::OffsetArray`.

[btilly]

Yes, but did the programmer tell the type system that they are expecting an OffsetArray, they have tested it, and it will work correctly?

The existence of a mechanism does not guarantee its correct use. As that link demonstrates.