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From: mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin)
Newsgroups: comp.edu,uw.general
Subject: Re: Recursion Summary
Message-ID: <9896@milton.u.washington.edu>
Date: 25 Oct 90 05:58:00 GMT
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In article <9892@milton.u.washington.edu> wiml@milton.u.washington.edu (William Lewis) writes:
>   But the CPU itself is iterative, not recursive. The CALL instruction
>finishes when the subroutine begins, not when it ends.

That is a wierd definition of iterative vs. recursion, although it may
be what Computer Science classes are teaching these days.  What if the
"subroutine call" is a trap instruction, or an instruction that is
implemented in hardware on some CPU models, in microcode on others,
and in macrocode on others?

By your argument there is no such thing as recursion.

The notion that high-level languages are any difference from machine
language can be disproved by the following C program:

	int foo (int n);
	main ()
	{
	  printf ("%d\n",foo (10));
	  return 0;
	}

	foo (int n)
	{
	  _exit (0);
	  return n;
	}

The call to each of main(), printf(), and foo() is finished as soon as
the stack frame is established.  A separate return, whether explicit
or implicit, is needed to unwind the stack and resume processing at
the caller.

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