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Comment by threethirtytwo | Hacker News Reader

I really believe in FP and Haskell but I want to examine this objectively. Empirically speaking is what Mercury done successful truly because of Haskell? Do they have metrics that demonstrates clear superiority along some vectored trait like complexity, bug count, etc?

>A couple million lines of Haskell, maintained by people who learned the language on the job, at a company that moves huge amounts of money? The conventional wisdom says this should be a disaster, but surprisingly, it isn't. The system we've built has worked well for years, through hypergrowth, through the SVB crisis that sent $2 billion in new deposits our way in five days,1 through regulatory examinations, through all the ordinary and extraordinary things that happen to a financial system at scale.

This one is quite telling. Do people have counter examples?

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Without having run the whole company twice in parallel, once using Haskell and again in some other language, and without having measured both runs exactly the same way, I don't think metrics like you're interested in could possibly have sufficient context to mean anything reliable.

Obviously Mercury is successful, and obviously Haskell is how they did it. So it's essential to their success. Would it be instrumental to anyone else's anywhere else doing anything else? Can't possibly know, I don't think.

I’m asking for solutions and answers. Yeah. I’m aware of how hard it is to get metrics.

You can still compare lines of code and bug rate over the same period of time.

You can, but then "The cake is a lie.", because linecount and bug rate, when concieved as proxies for productivity[1] or quality rarely match up with reality in a way that allows you to make predictions or reason about past outcomes.

You can reason about frequency of particular types bugs, such as null pointers or overflow, or whether those bugs can occur at all.

[1] https://www.folklore.org/Negative_2000_Lines_Of_Code.html

It's probably more likely it comes down to: if your programmers are capable of learning and working in Haskell, they're likely a cut above in terms of keenosity and nerdiness and motivation around programming, and you're likely to early-cull the people who just got into CS because mom and dad told them it paid well. That's likely to help produce better overall code health.

The irony of these fancy FP languages that were designed to develop compilers or to get PL academics off is that they're actually also really good at the most mundane code imaginable.

Being able to minimize boilerplate and have strong refactoring and bug resistant types is a huge edge.

The only problem is their ecosystems are limited so you might spend more time than you like implementing an API or binding a system library.

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