[cfiggers]

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.

[threethirtytwo]

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.

[IIsi50MHz]

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