Lean definitely intends to be usable as a general purpose language someday. but I think the bulk of the people involved are more focused on automated theorem proving. The Lean FRO [0] has funds to guide development of the language and they are planning to carve out a niche for stuff that requires formal verification. I'd say in terms of general purpose programming it fits into the category of being "relatively far from haskell in terms of maturity".
[0] https://lean-fro.org/about/roadmap-y2/