> On my remark about Haskell/GHC with extensions, I'm talking about things like the Dynamic type, existential types, HList and about experiments like OOHaskell.

> On my remark about Haskell/GHC with extensions, I'm talking about things like the Dynamic type, existential types, HList and about experiments like OOHaskell. The point of subtyping is implicit coercions: using a type T1 when T2 is expected, without extra conversion. Dynamic and existentials are not subtypes (you need fromDyn or the data constructor introducing the existential). OOHaskell is as far as I know a failed and abandoned experiment. Who uses it? I don't know HList enough to comment, but it's based on GHC's constraint system and very much unlike subtyping in Scala. I agree with you that OOP is not the same as subtyping. Here's how variance complicates stuff in Scala: http://www.reddit.com/r/haskell/comments/zxcks/haskell_vs_f_vs_scala_a_highlevel_language/c68ybn1 http://www.reddit.com/r/haskell/comments/zxcks/haskell_vs_f_... >> The ecosystem matters the least when learning for learning sake. > Actually it matters the most, as good learning can only happen if you go forth and experiment on your own. That's why some languages like Python are popular [...] No, the comparison with Python is not fair. Python is a polar opposite of Haskell. People learn Python as a scripting language. You can learn the basics of the language extremely fast. There's little didactic value in Python the language once you know imperative programming. Then real work comes by learning libraries, frameworks, APIs etc. People learn Haskell as a way to broaden horizons, see a different paradigm. GHC, with standard library only (covering a lot less than Python's batteries) gives enough material to experiment for months if not years. It takes a while to understand GADTs, type classes, kinds, higher-order types, type families etc. Learning Haskell is much closer to learning proofs/doing puzzles than software engineering. The fact that you made your program compile after two hours is rewarding like solving a puzzle. I have seen people attempting to build a concurrent web server in Haskell in first week, not knowing how laziness or class instances work and blaming Haskell for making things weird and unintuitive. The practical mindset of Python does not pay off in Haskell. So I agree with OP - the ecosystem is least concern when learning FP for learning sake.