Definitely, but I'd imagine this is being frowned upon because the realistic (and non-fanatic) folks who use Haskell, use it mostly for these advanced features, I'd imagine. Could be wrong.
Can not resist. The tension between 'basic feature set' and an admittedly superficial reading of the docs is very funny. The manifesto links to https://github.com/commercialhaskell/rio#readme and urges us to use the rio library to get started. Upon opening the rio link and scanning for a list of the 'basic feature set', I stumble upon the first block of quoted code. After removing 39 eoln characters in respect for the HN audience, it reads:
39 language extensions just to get started. This screams 'incredibly complicated', even if perhaps reality is rather more mundane. Consider the 40th language extension: GradualTyping, so perhaps those that would rather write code about data than about types using a half baked and evolving type language (which taken to its logical conclusion will have to become a full fledged theorem prover in the Coq / Idris / Agda / Lean lineage anyways) could get their jobs done.
This is a common response to Haskell language extensions. It comes from a misunderstanding of what a language extension is. A Haskell language extension is not "something that radically changes the language"; it is "a small, self-contained, well-tested piece of functionality that for whatever reason wasn't part of the Haskell 2010 standard". In any other language a "language extension" would just be "a feature of the language".
