[tel]

To be honest, I think Haskell is the best language I know of for fast iteration as well. You can successfully create and manage far worse, yet working code when you've got a good type-driven guardrail. A common pithy quote, which I agree with wholeheartedly, is that "`IO` is the best imperative language out there today".

There's definitely a lot of missing documentation about this folk practice of "fast, loose, shitty Haskell" due to the strong culture of pretty code that's also enabled by Haskell. I remember seeing a video presented at CUFP that went into the merits here, though.

Essentially, this is a "tricky" concept because you want to design your types to be exactly as restrictive as you can afford without having to think too much. It probably requires a good grasp of the Haskell type system applied in full glory in order to bastardize it just right.

So, tl;dr?

I think types are the ultimate fast iteration tool, but this is not a well-documented practice.