optional-chain-monads.md

Consider this Swift:

let addr: String? = person?.job?.address

In this case, if person is nil, it returns nil, otherwise it binds the job, and repeats.

This same thing is expressed in Haskell as:

addrOf person = person >>= (\p -> ((job p) >>= (\job -> (address job))))

Or the much less unwieldy:

addrOf person = do
  p <- person
  j <- job person
  return $ address j