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Re: primitive instruction for programming

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David Brown <david.brown@hesbynett.no> writes:

> On 21/04/15 10:34, asetofsymbols@gmail.com wrote:
>> int s[10000];
>> int *r=s+9999; *Lim=r, z;
>> 
>> #define G(a,b)  if(a)goto b
>> #define push(a) r>=s?*r=a,--r:0
>> #define pop(a)  r<Lim?++r, a=*r:0
>> #define ret     pop(z); G(1,z);
>> #define ca(a,m) z=m; push(z); G(1,a)
>> 
>> f(a,b,c)
>> 
>> Should traslate to
>> push(c); push(b); push(a);
>> ca(f,label);
>> label:
>> pop(z);pop(z);pop(z);
>> 
>
> You have /completely/ missed the point.
>
> The original claim was that G /alone/ could replace any control
> structure in C.  It can't - it is unable to replace the call/return
> mechanism needed for recursion, which is /required/ for some types of
> functions (like the Ackerman function given).  You can add extra data,
> such as a stack, and use that along with G to implement recursion - but
> you cannot do it with just G.

That's not how this problem is usually set up; adding data is not
usually considered a problem -- after all, much of the data is there in
the recursive function version anyway.  The rules of the "what makes a
minimal computational system" usually permit any finite amount of extra
data that might be required (though in some more restrictive cases one
might object to quantities that grow exponentially with the problem
size).

-- 
Ben.

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Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 14:27 -0700
  Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 15:12 -0700
    Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 00:17 +0100
      Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-22 11:07 -0700
  Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 09:04 +0200
    Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-21 03:02 -0500
    Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-21 01:34 -0700
      Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 11:34 +0200
        Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-21 11:48 +0100
          Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 13:10 +0200
      Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 10:53 +0100

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