🚀 go-pugleaf

How to allow breaking out of arbitrary loops, which you might otherwise
have to do like this:

>> done := false;
>> while not done do begin
>>	do_some;
>>	done := done | done_now;
>>	if not done then begin
>>		do_some_more;
>>		done := done | done_already;
>>		end;
>>		else do_even_more;
>>	end;

In some recent versions of Logo, and also in Lisp, you have the
`throw/catch' construct, which I think looks a lot better:

	to a_program
	    catch 'foo [
			   forever [
				     repeated_bit
				     if <condition> [
						       throw 'foo
						    ]
				     other_repeated_bit
				   ]
			]
	    last_bit

When the `throw 'foo' is executed, execution resumes at `last_bit'.
Catches may be nested.

-- 
------------------------------------------------------------------------------
From Ken Johnson, AI Applications Institute, The University, EDINBURGH
Phone 031-225 4464 ext 212
Email k.johnson@ed.ac.uk