why list monad not in core

Stream: lean4

[Thomas Karoni]

Hello!
I was wondering why the monad instance for List is not in core. pure and bind are defined there but not the monad instance. I think I found one in mathlib though.
Is it on purpose? If so what's the idea behind that?

[David Renshaw]

there was some discussion on this a few months ago: https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/question.3A.20why.20List.20is.20nolonger.20Monad.3F/near/436347641