That blog post doesn’t make sense to me at all. The author is going from full modern Haskell (since he mentioned Servant and Beam, you could tell almost every file uses dozens of GHC extensions beyond what Haskell2010 gives you) to Python with dynamic types. He could instead rewrite the Haskell to use less modern type system features and get so much faster compilation speed.

Also GHC has an interpreter. It powers the REPL. No need to compile everything if you’re just experimenting. I do find that in the Haskell world the REPL is criminally underused compared to Python.

And the rest of your comment doesn’t make sense; this shop is rewriting their infra (not UI) from Haskell to Python.