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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

#21

Post by wodenokoto »

ur-whale wrote: post #6

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

According to the article the problem is in the ecosystem, and partly the standard lib.

Basically it doesn't matter if Julia the language is fine, if all the stats packages make wrong calculations. Then what is the point of Julia, if you have to rewrite all things? might as well use another language where you trust the result of the ecosystem, since it is the ecosystem you need in order to produce results.

Re: Correctness and composability bugs in the Julia ecosystem

#22

Post by exyi »

ur-whale wrote: post #6

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

Yea, all are just bugs, not some intrinsic flaws in the language.

Given Julia's goals (performance, abstractions, accessible to science people), it's understandable if they had slightly higher bug concentration than other (similarly sized) ecosystems.

Re: Correctness and composability bugs in the Julia ecosystem

#23

Post by CoastalCoder »

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.

I think the real test will be whether or not Julia's custodians / developers start putting a greater focus on semantics and correctness.

When a language's raison d'être is to try out certain ideas, it probably makes sense for a while to ignore corner cases and rigor. But as the author points out, they eventually become gating factors for wider adoption.

Re: Correctness and composability bugs in the Julia ecosystem

#24

Post by adolph »

Oftentimes people describe languages as "Turing complete" but how often do they talk about languages being "Gödel incomplete?" Another way of stating maybe is "Are what some call flaws what others call features?"

https://stackoverflow.com/questions/7284/what-is-turing-comp...

https://plato.stanford.edu/entries/goedel-incompleteness/

Re: Correctness and composability bugs in the Julia ecosystem

#25

Post by Q6T46nT668w6i3m »

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.

Re: Correctness and composability bugs in the Julia ecosystem

#26

Post by adgjlsfhk1 »

RcouF1uZ4gsC wrote: post #17

> If you pass it an array with an unusual index range, it will access out-of-bounds memory: the array access was annotated with @inbounds, which removed the bounds check. It think making indexes configurable is a huge mistake. Even if they are not ideal for the situation, having a single way to do indexes makes a huge source of confusion and potential bugs just go away. And this is orthogonal to whether you pick 0 or…

OffsetArrays can be really nice for things like convolutions. For example, it ends up being really natural to have a matrix that is indexed on [-2:2, -2:2] to implement a gausian blur. It definitely is a potential bug source though.

Re: Correctness and composability bugs in the Julia ecosystem

#27

Post by davisoneee »

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…

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, ... x_n or SUM 1 to N) start with 1, so for these 1-based can be a more natural/direct translation of mathematical notation to code.

Re: Correctness and composability bugs in the Julia ecosystem

#28

Post by arksingrad »

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.

@inbounds isn't the problem, it's incorrect usage of it. The poor docstring is absolutely a problem though, you should be iterating over eachindex(A), not 1:length(A).

Re: Correctness and composability bugs in the Julia ecosystem

#29

Post by sdfhdhjdw3 »

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.

The problem isn't that 1-base indexing can be "fixed" in Julia. The problem is that you see 1-based indexing as a flaw.
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