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Why GADTs matter for performance (2015)

(blog.janestreet.com)
83 points hyperbrainer | 6 comments | 10 May 25 13:55 UTC | HN request time: 1.301s | source | bottom
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goldchainposse ◴[12 May 25 19:17 UTC] No.43966573[source]▶
I know Jane Street love OCaml, but you have to wonder how much it's cost them in velocity and maintenance. This is a quant firm blogging about a programming language they're the most famous user of.
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1. kryptiskt ◴[12 May 25 19:56 UTC] No.43966877[source]▶
Why do you assume it's a drag for them and not a competitive advantage? I don't know if it's such a terrible thing to use a slightly out of mainstream language, when the standard in the business is to accumulate tens of millions of lines of C++.
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2. ackfoobar ◴[12 May 25 20:04 UTC] No.43966932[source]▶
Agreed, indeed I believe they have mentioned that OCaml gets them to ship quicker because they are more confident with the correctness of changes.

But being outside of the mainstream may mean you need to occasionally debug more esoteric stuff: https://gallium.inria.fr/blog/intel-skylake-bug/ I'm sure Jane Street can afford doing that, but I'm not so sure if a small team can.

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3. gjadi ◴[12 May 25 21:22 UTC] No.43967582[source]▶
That was an interesting read, thanks. However I fail to see how it's an issue specific to ocaml. It was a bug in the Skylake processor triggered by a special pattern of instructions produced by gcc. Ocaml built with clang was ok because it doesn't used the same pattern. Did I miss something?
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4. ackfoobar ◴[12 May 25 21:42 UTC] No.43967739{3}[source]▶
If the JVM encountered the same bug other people would have discovered it before me. Most probably I won't even know the bug exists.
5. goldchainposse ◴[12 May 25 22:10 UTC] No.43967922[source]▶
> Why do you assume it's a drag for them and not a competitive advantage?

Because despite them being very open about it, no one else does it, and every distinguished engineer who pushes a weird tech choice will justify and defend it.

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6. cdaringe ◴[13 May 25 07:02 UTC] No.43970287[source]▶
People that haven’t used ocaml think it’s weird. I picked it up casually in 2020. It might not be popular, but it’s certainly not weird. It’s actually quite fantastic. These days I rarely ever use it, but I wish I did!