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Correctness and composability bugs in the Julia ecosystem

yuri.is

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Re: Correctness and composability bugs in the Julia ecosystem

#31

Post by sdfhdhjdw3 »

karmakaze wrote: post #11
dekhn wrote: post #4

Wait, are those examples real? I remember complaining about 1-bsaed indexing only to be told "julia is great! we have offsetindex". If it's a source of bugs, that ... greatly reduces my future interest in adopting the language.

I was wondering if the 1-based arrays (and option to change index base) would factor into this. > OffsetArrays in particular proved to be a strong source of correctness bugs. The package provides an array type that leverages Julia’s flexible custom indices feature to create arrays whose indices don’t have to start at zero or one. Array indexing is such a core thing and I don't understand why anything mathematical or…

> Array indexing is such a core thing and I don't understand why anything mathematical or scientific would start with 1.

Because that's how maths work? Literally everywhere in maths you count from 1, except in software engineering. That's why. I hope that clarified your confusion.

Re: Correctness and composability bugs in the Julia ecosystem

#32

Post by temp8964 »

karmakaze wrote: post #11
dekhn wrote: post #4

Wait, are those examples real? I remember complaining about 1-bsaed indexing only to be told "julia is great! we have offsetindex". If it's a source of bugs, that ... greatly reduces my future interest in adopting the language.

I was wondering if the 1-based arrays (and option to change index base) would factor into this. > OffsetArrays in particular proved to be a strong source of correctness bugs. The package provides an array type that leverages Julia’s flexible custom indices feature to create arrays whose indices don’t have to start at zero or one. Array indexing is such a core thing and I don't understand why anything mathematical or…

> Array indexing is such a core thing and I don't understand why anything mathematical or scientific would start with 1.

From data analytic point of view, indexing should start with 1. When we analyze a data table, we always call the first row as the 1st row, or row #1, not row #0. It will be very strange to label rows as 0, 1, 2, 3, .... It may be fine for people with Computer Science background. But it would create so much confusion for almost everyone else...

Re: Correctness and composability bugs in the Julia ecosystem

#33

Post by hprotagonist »

karmakaze wrote: post #11
dekhn wrote: post #4

Wait, are those examples real? I remember complaining about 1-bsaed indexing only to be told "julia is great! we have offsetindex". If it's a source of bugs, that ... greatly reduces my future interest in adopting the language.

I was wondering if the 1-based arrays (and option to change index base) would factor into this. > OffsetArrays in particular proved to be a strong source of correctness bugs. The package provides an array type that leverages Julia’s flexible custom indices feature to create arrays whose indices don’t have to start at zero or one. Array indexing is such a core thing and I don't understand why anything mathematical or…

> Array indexing is such a core thing and I don't understand why anything mathematical or scientific would start with 1.

So, no FORTRAN, huh?

Re: Correctness and composability bugs in the Julia ecosystem

#34

Post by jjgreen »

davisoneee wrote: post #27
karmakaze wrote: post #11

Earlier quoted context omitted.

I was wondering if the 1-based arrays (and option to change index base) would factor into this. > OffsetArrays in particular proved to be a strong source of correctness bugs. The package provides an array type that leverages Julia’s flexible custom indices feature to create arrays whose indices don’t have to start at zero or one. Array indexing is such a core thing and I don't understand why anything mathematical or…

I'll start by saying that I greatly prefer 0-based, and have used but 0- and 1-based indexing, but the choice is largely arbitrary. 0 makes sense as the '0-th offset' when thinking from a pointer perspective, but I often find when teaching, that 1-based comes more naturally for many students (the 'first' item). You mention mathematical or scientific work...but I often/mainly see enumerations (such as weights x_1, x_2…

Not for polynomial coefficient indices :-)

Re: Correctness and composability bugs in the Julia ecosystem

#36

Post by markkitti »

Q6T46nT668w6i3m wrote: post #13
ur-whale wrote: post #6

The examples provided feel more like bugs in various libraries than an actual problem intrinsic to Julia the language.

@inbounds is a Base feature.

Yes, and it is a perfectly fine feature when applied correctly. It would be incorrect to assume that an `AbstractArray` starts at `1` or `0` which is why the updated example now correctly uses `eachindex`: https://docs.julialang.org/en/v1/devdocs/boundscheck/#Elidin...

If you want to assume that an array starts at `1` one needs to require an `Array` rather than an `AbstractArray`.

Re: Correctness and composability bugs in the Julia ecosystem

#37

Post by NeutralForest »

s_Hogg wrote: post #12
NeutralForest wrote: post #3

I mean this looks like good potential targets to improve the language moving forward, it's healthy to not be in awe of your tools and push to make them better. I don't see this as "bad" honestly.

It seems like the point of the article is that that push is insubstantial, if it even exists. Given the language has been around this long it's a bit worrying that stuff like that is the potential target for moving a language forward. Julia has always had a reputation in my mind at least of being "by academics, for academics" and there's unfortunately a dark side to that in terms of reliability and maintainability. T…

I suppose we'll see? Honestly this is maybe an opportunity to adjust some goals of the language if this is the feeling people are having now and outreach to purely CS and SE people will probably be needed but seeing the presence it has at the MIT, I don't see it being a problem.

Re: Correctness and composability bugs in the Julia ecosystem

#39

Post by catchclose8919 »

Q6T46nT668w6i3m wrote: post #25
catchclose8919 wrote: post #10

Only thing "interesting" to me there would be the automatic differentiation bugs ...but is there any argument as to them being the fault of the language, instead of just poor engineering from the library developers' part? I mean, one can't expect all algorithms to work correctly with all datatypes just because the compiler allows that code to run ... you write tests and guarantee numerical stability for a small subse…

I think the author addresses this. It’s a Catch-22. If you restrict use to a small subset of types you’re undermining one of Julia’s best features. As someone who has been writing a lot of numerical analysis code recently, I would absolutely love a type system that could describe and enforce numerical stability traits.

> a type system that could describe and enforce numerical stability traits

Wow, that sounds cool! have your reasearched if anyone has done anything in this are? how would you even start to approach the problem?

Do you think it has any change of being done without massive sacrifices to performance?

Re: Correctness and composability bugs in the Julia ecosystem

#40

Post by coldtea »

karmakaze wrote: post #11
dekhn wrote: post #4

Wait, are those examples real? I remember complaining about 1-bsaed indexing only to be told "julia is great! we have offsetindex". If it's a source of bugs, that ... greatly reduces my future interest in adopting the language.

I was wondering if the 1-based arrays (and option to change index base) would factor into this. > OffsetArrays in particular proved to be a strong source of correctness bugs. The package provides an array type that leverages Julia’s flexible custom indices feature to create arrays whose indices don’t have to start at zero or one. Array indexing is such a core thing and I don't understand why anything mathematical or…

>Array indexing is such a core thing and I don't understand why anything mathematical or scientific would start with 1.

Because starting with 0 is neither math nor array indexing in general.

It's just how the base addresss of an array pointer memory block was referenced in C (and it spread from there).

Which is why all math focused languages use 1-based (fortran, apl, matlab, r, mathematica, etc.)

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