Abstract: APL, an interpretive processor, cooperates with external routines by calling those external routines to process data passed to them and receives results from the external routines. The called external routines, during their respective execution of the call, can request internal services of the calling APL interpretive processor. Such requests include execution of internal APL functions or operators, calling other external routines, recursive execution of external routines, and setting or obtaining values of internal APL data items.

Abstract: A method for executing external processes and for accessing external data from within an interactive language workspace. The workspace task referencing the external processes or data is synchronized and locked until the process is completed or the data referenced. The method steps provide establishing a message interface and utilize coercion of arguments in a dynamic environment. This permits, for instance, the invocation of a FORTRAN language process or from within an APL workspace and a return of information from said external processor without terminating the APL workspace.