> Synthetic data pipelines should be mostly invariant to the programming language, as long as the output is correct.

Well, you can adapt your PHP producing pipeline to produce Haskell code that is correct in the sense of solving the problem at hand, but getting it to produce idiomatic code is probably a lot harder.

I think the trick with Haskell is that you can write types in such a way that the APIs that get generated are idiomatic and designed well. The implementations of individual functions might be messy or awkward, but as long as those functions are relatively small—which is how I tend to write my non-AI-based Haskell code anyhow!—it's not nearly as important.