Cooperating input and output stack processors
Cory F. Skutt · ACM SIGAPL APL Quote Quad · 1983
As a complement to an enhanced input stack processor (ISP), an output stack processor (OSP) has been produced that captures output lines from VSAPL, places them on a stack, and makes them available to an APL application through the shared variable interface. Together, these processors provide three fundamental facilities: execution of system command sequences; error and exception handling; and retrieval of information not available through system variables. This presentation discusses the objectives, challenges, design and applications of these processors. A brief comparison of error-handling capabilities is included.