Flow-control structures: Difference between revisions
→Elaborations on GO TO
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GO TO 1000
1103 CONTINUE</lang>
So that "subroutine" 1000 would be invoked, which then invokes subroutine 2000, which returns via THENCE. And, instead of using simple variables such as THENCE and WHENCE, one could use an array and treat it like a stack... Those familiar with LISP or FORTH and similar languages will recognise a struggle to create new "verbs" from existing verbs, and their resulting usage in compound expressions. This is Philip Greenspun's "tenth" rule of programming.
Another such usage would be to implement "coroutines", the classic example being to imagine a system that processes both Fortran statements and Fortran commentary, but each in their own way. After scanning some Fortran source, commentary is found so control flows to resume the commentary processing from where it had left off, then when further Fortran source is found, control flows back whence the Fortran source process left off. This is quite different from having subroutines FCODE and FCOMM which when invoked start at their start each time (as say when a new statement begins) rather than picking up where they left off because the switches occurred in the middle of a statement. Quite aside from questions of mutual recursion.
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