fn receive (receiver) -> {
  print! ("receiving in", self (), "with msgs", msgs())
  if empty? (msgs ())
    then {yield! (); receive (receiver)}
    else do msgs () > first > receiver
}

fn foo? (val) -> receive (fn (msg) -> match report!("scrutinee is", msg) with {
  (:report) -> {
    print! ("LUDUS SAYS ==> value is {val}")
    flush! ()
    foo? (val)
  }
  (:set, x) -> {
    print! ("LUDUS SAYS ==> foo! was {val}, now is {x}")
    flush! ()
    foo? (x)
  }
  (:get, pid) -> {
    print! ("LUDUS SAYS ==> value is {val}")
    send (pid, (:response, val))
    flush! ()
    foo? (val)
  }
  x -> print! ("LUDUS SAYS ==> no match, got {x}")
})

let foo = spawn! (fn () -> foo? (42))
print! (foo)
send (foo, (:set, 23))
yield! ()
send (foo, (:get, self ()))
yield! ()
fn id (x) -> x
receive(id)