: (pty)         ( --  fd )
                2 posix-openpt
                  dup grantpt throw
                  dup unlockpt throw
                  ." PTY opened on " dup pad $100 rot ptsname pad swap type cr
                ;

: pty           ( 1 | 0 -- )
                if (pty) dup (sink-id) ! (source-id) ! abort
                else 0 (source-id) ! 1 (sink-id) ! abort
                then
                ;