HELP NEXTLOOP                R. Barrett et al, 1984, A.Sloman 1986

nextloop(<optional integer>)

In a looping construct, NEXTLOOP causes control to jump to just before
the syntax word closing the loop, for example ENDWHILE in a WHILE loop,
and ENDFOR in a FOR loop. This causes the enclosing loop to be
restarted.

If an integer N is given, the N'th enclosing loop is 'continued'. The
integer defaults to 1 if not supplied.

For example, given a vector of ordered lists of integers, find the
list with the smallest even integer.

    define is_even(n);
        isinteger(n) and n rem 2 == 0
    enddefine;

    define search_smallest_even(vector_of_lists)->smallest;
        ;;; return the smallest even integer
        lvars vector_of_lists, smallest=999999999999999999999,
              index,list,item;
        for index from 1 to datalength(vector_of_lists) do
            subscrv(index,vector_of_lists) -> list;
            for item in list do
                if is_even(item) and item < smallest then
                    item -> smallest;
                    [found ^item - start next list] =>
                    nextloop(2)     ;;;CONTINUE 2nd enclosing loop
                endif;
            endfor
        endfor
    enddefine;

    search_smallest_even({[ 1 3 7 88 502] [3 7 40 73] [5 8 20 99]}) =>
    ** [found 88 - start next list]
    ** [found 40 - start next list]
    ** [found 8 - start next list]
    ** 8

If NEXTLOOP is followed by an integer, N, the Nth enclosing loop is
re-started.

N.B: NEXTLOOP is not a procedure and cannot be called by a procedure
inside the loop: it must be used in the loop body itself. Moreover,
the integer cannot be represented by a variable or an expression evaluating
to an integer. (This effect can be achieved using * GO_ON.)

See also HELP
 *QUITLOOP   - to jump out of one or more enclosing loops
 *QUITIF     - to jump out of a loop if a condition becomes true
 *QUITUNLESS - to jump out of a loop if a condition becomes false

 *NEXTIF     - to restart a loop if a condition becomes true
 *NEXTUNLESS - to restart a loop if a condition becomes false

 *LOOPS      - for types of iteration available in POP-11
 *CONTROL    - for control structures available in POP-11

REF * SYNTAX - for more on syntactic constructs in POP-11

-----<Copyright University of Sussex 1986.  All rights reserved.>-------