Miguel <[EMAIL PROTECTED]> writes:
>>On 9/3/07,Vimal<[EMAIL PROTECTED]> wrote:
>>>while E do
>>>S
>>>if F then
>>>break
>>>end
>>>T
>>>end
>>>
>>>He then asked us to *prove* that the above programming fragment cannot
>>>
>>>be implemented just using if and while statement, even if S and T can
>>>be duplicated a finite number of times
>>But it IS possible. Just add a boolean flag:
>
> Possibly, you are not allowed to change the sequence of
> machine operations at all. See, if you change
> "while(A){B}" to "if(A){B};while(A){B}", the sequence is
> exactly the same; but it's not possible in this case.
It depends on arbitrary restrictions on what constitutes an
(boolean) expression, something that is anathema to
functional programmers :-) Spot the language:
while if E
then S; F
else False
fi
do T
od
> It reminds me of a paper by Knuth, where he states that
> "goto" statement is necessary; don't remember the title,
> however.
I don't remember needing a goto in Haskell...
--
Jón Fairbairn [EMAIL PROTECTED]
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