Re: Loops (was Re: do { quit; } else { })

Michael S <already5chosen@yahoo.com> writes:

On Sat, 10 May 2025 06:43:38 -0700
Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>

Michael S <already5chosen@yahoo.com> writes:
>

On Sun, 04 May 2025 07:31:11 -0700
Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
[...]
Also having just one form of loop with pre-condition strikes me as
more elegant.  Since elegance is strongly subjective, I have no
logical arguments in support of me feelings.

>
In a recent posting I gave some statistics about the three different
kinds of looping controls (while,for,do/while).  do/while loops were
almost 20% of all loops, and more than a quarter of the two kinds of
loops other than for().  Besides being a more pragmatic choice, I
think having the three kinds of loops be distinct in the language is
a better choice, because how we think of the different kinds of loop
is different, and it's helpful to have those differences be readily
apparent in the program, rather than needing to reconstruct them by
looking at code around the loop control fragment.

>
That sounds like misunderstanding.
I didn't suggest one loop construct.  I suggested two constructs:  for()
for loops with pre-condition and do-while for loops with post-condition.

Yes, I did misunderstand you.  The alternative meaning didn't occur
to me.  I see it now.

The same posting I mentioned in the previous response gave while()
loops as occurring more than for() and do/while() combined.  I
conceptualize for() loops quite differently than while() loops, and
vice versa.  By analogy to the only-two-kinds-of-loops suggestion,
the language could forego switch() and provide only if()/else.  To
me, neither of those what-might-be-called-simplifications seems like
a good trade.  Have you asked other people to see what their
reactions are?

Incidentally, a language change to C was once proposed, so that
a do/while could also have an expression after the while().
Note that this change is backwards compatible with C as it is,
because a simple semicolon after while() is an empty statement.
Adopting this proposal would mean that the language would allow,
for example

   do {
      // this part will always be done at least once
      // and once more for each time 'condition' is true
   } while(  condition  ){
      // this part will be done zero or more times
   }

allowing a convenient way of writing "loop-and-a-half" type
loops.  Do you have any reaction to this idea?  Suppose
the just plain while() style were eliminated, so ordinary
while() loops would instead be written as

   do ; while( condition ){
      // body of while loop
   }

Is that better or worse than having a separate while() statement?