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@REPLYADDR dxf <dxforth@gmail.com>
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On 25/09/2023 12:48 am, Hans Bezemer wrote:
> On Saturday, September 23, 2023 at 11:33:09 AM UTC+2, dxf wrote:
>> YouTube offered this to me. Perhaps the world is catching on.
>> So what shall we do with ANS CASE :)
>
> It`s nothing new - but note it`s also a paradigm shift. In the
old days the world wanted
> a single return from a function - which was logical in a sense,
because long functions
> were still very much a reality. Using too many exit points was
waiting for an accident to
> happen. Maybe it was also fashionable to write long functions to
minimize function call
> overhead. Especially on older processors it`s not insignificant -
building a stack frame,
> discarding it on exit.. you catch my drift.
There are reasons for continuing to use ELSE but how did we get
ELSE ? ELSE is a
logical complement to IF and I suspect that`s why every language
has it. Having
ELSE, it has become a habit - one whose cost we`ve not really considered before.
> I quickly found out all that is not much of an issue with
Forth, because small functions
> (words) were the paradigm there (read "Thinking Forth"). So I
quickly switched to multiple
> exits.
>
> On 4tH this was amplified by the introduction of the optimizer.
Using ;THEN instead of
> ELSE provided much tighter code, because it discarded superfluous
jumps. So if there
> was nothing after a THEN to execute, ELSE could be replaced by
a ;THEN quite easily.
>
> BTW, if you got an ELSE clause and the IF requires a 0= you
can further simplify by
> switching the IF and ELSE clauses, so there is no need for 0= anymore.
>
> Anyways, you see that the C-like world is moving to shorter
functions, because they`re
> much easier to control. Of course, there are still exceptions -
e.g. when speed is the prime
> directive. I wouldn`t like to break up my VM code in smaller
chunks, for example. Worse,
> I`m inlining a *lot* there for the same reason.
>
> I don`t know how other Forths are in this regard, but on
smaller tables CASE..ENDCASE is
> significantly faster than any other technique - with the exception
of direct indexed access.
> On smaller tables it even easily beats a binary search. So for
that reason - and that reason
> alone - I`m keeping that construct in.
I agree. For me it`s the syntax rather than the mechanism that irritates.
ELSE (aka ENDOF) is built into the syntax and the user is stuck with it.
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