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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: transpiling to low level C
Date: Mon, 23 Dec 2024 14:00:38 -0800
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Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:

> On 22.12.2024 07:01, Waldek Hebisch wrote:
>
>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>>
>>> On 21.12.2024 02:28, Tim Rentsch wrote:
>>>
>>>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>>>>
>>>>> On 16.12.2024 00:53, BGB wrote:
>>>>>
>>>>>> [...]
>>>>>>
>>>>>> Pretty much all higher level control flow can be expressed via goto.
>>>>>
>>>>> A 'goto' may be used but it isn't strictly *necessary*. What *is*
>>>>> necessary, though, that is an 'if' (some conditional branch), and
>>>>> either 'goto' or recursive functions.
>>>>
>>>> Conditional branches, including 'if', '?:', etc., are not strictly
>>>> necessary either.
>>>
>>> No? - Can you give an example of your statement?
>>
>> Look at example that I posted (apparently neither you nor Tim
>> looked at my posts where I explained in detail how to translate
>> goto program (with conditional jumps) into program that contains
>> no goto and no conditional jumps).
>
> I'm not sure but may have just skimmed over your "C" example if it
> wasn't of interest to the point I tried to make (at that stage).
>
>> Or try to figure out how to do this knowing that C has function
>> pointers.
>
> I will retry to explain what I tried to say... - very simply put...
>
> There's "Recursive Functions" and the Turing Machines "equivalent".
> The "Recursive Functions" is the most powerful class of algorithms.
> Formal Recursive Functions are formally defined in terms of abstract
> mathematical formulated properties;  one of these [three properties]
> are the "Test Sets".  (Here I can already stop.)
>
> But since we're not in a theoretical CS newsgroup I'd just wanted
> to see an example of some common, say, mathematical function and
> see it implemented without 'if' and 'goto' or recursion. - Take a
> simple one, say, fac(n) = n! , the factorial function.  I know how
> I can implement that with 'if' and recursion, and I know how I can
> implement that with 'while' (or 'goto').
>
> If I re-inspect your example upthread - I hope it was the one you
> wanted to refer to - I see that you have removed the 'if' symbol
> but not the conditional, the test function;  there's still the
> predicate (the "Test Set") present in form of 'int c2 = i < n',
> and it's there in the original code, in the goto transformed code,
> and in the function-pointer code.  And you cannot get rid of that.

Are you sure about that?