Roy Monad syntax bug

gistfile1.txt

let ioMonad = {
        return: \x -> (\() -> x)
        bind: \action f -> (\() -> 
                             let value = action ()
                             let action2 = f value
                             action2 ()
                           )
      }

let putStrLn line = (\() -> console.log line)

let main = do ioMonad
	_ <- putStrLn "a"
	putStrLn "b"
    
main ()

If line 13 was just

putStrLn "a"

The letter "a" doesn't get printed.