Problem Statement

Imperative programs like to jump around, but some languages restrict these jumps. Many structured languages restrict their conditional structures and loops to local jumps within a function. Some assembly languages limit certain jumps or branches to a small range. This task is to demonstrate a local jump and a global jump and the various other types of jumps that the language supports. For the purpose of this task, the jumps need not be used for a single purpose and you have the freedom to use these jumps for different purposes. You may also defer to more specific tasks, like Exceptions or Generator. This task provides a "grab bag" for several types of jumps. There are non-local jumps across function calls, or long jumps to anywhere within a program. Anywhere means not only to the tops of functions! These jumps are not all alike. A simple goto never touches the call stack. A continuation saves the call stack, so you can continue a function call after it ends.

Use your language to demonstrate the various types of jumps that it supports. Because the possibilities vary by language, this task is not specific. You have the freedom to use these jumps for different purposes. You may also defer to more specific tasks, like Exceptions or Generator.

Let's start with the solution:

PROGRAM GOTO_ERR

LABEL 99,100

PROCEDURE P1
   INPUT(I)
   IF I=0 THEN GOTO 99 END IF
END PROCEDURE

PROCEDURE P2
99: PRINT("I'm in procdedure P2")
END PROCEDURE

BEGIN
100:
    INPUT(J)
    IF J=1 THEN GOTO 99 END IF
    IF J<>0 THEN GOTO 100 END IF
END PROGRAM