[REBOL] Re: [none idiom found?] The best shortcut word for "not none?"
From: lmecir::mbox::vol::cz at: 4-Sep-2006 8:47
Gregg wrote:
If you use ANY and ALL, the result may be none. The mezzanine that
converts a NONE result to a logic! value is FOUND?. I was going to
suggest that we add an alternative, for cases like this, to improve
the readability.
found? all [a = b zero? a - b]
That is, I've always read FOUND? as "was the value found?", as you
would when using FIND.
Now, whenever I think I've caught something that Carl missed, I try to
think about it a bit before requesting a change, because it usually
turns out that he's thought ahead of me and did the right thing; it
just takes me a little time to see it sometimes. :)
So, I was going to say a new word would be nice but, when I stopped to
think about it a little more, I realized that all I need to do is read
it in context. In the above example, it would mean "If it is found
that all the following are true...", which couldn't be clearer (I
tried to come up with better words, and couldn't).
So, thanks Carl, and thanks to Ladislav for making me think about
this.
What else in REBOL have you found that makes you think, or read code,
differently?
-- Gregg
Thank you for highlighting this issue. You made me think about it once
again and find out, that all problems may not be solved yet.
My original need was to obtain a LOGIC! value, so the question is, if I
shouldn't have used the TO function. Advantages:
a) TO LOGIC! is twice as fast as the FOUND? mezzanine and faster than
the NOT NONE? idiom
b) TO LOGIC! clearly shows what my intention is
c) TO LOGIC! does not behave exactly like FOUND? sometimes. See TO
LOGIC! FALSE and the question is, which result is appropriate for the
specific usage. For the above use this question is unimportant, but it
may occur elsewhere.
Even when we really need to know whether something has been found, the
situation is complicated. See e.g.:
found? select 1 reduce [1 none]
, which is related to the question, what you expect when writing:
switch/default 1 reduce [1 none] [2]
Discussion and your preferences are welcome.
-Ladislav
