[REBOL] Re: Newbie expression question
From: joel:neely:fedex at: 11-Oct-2003 22:30
Ooops! I hit the send button before finishing...
[SunandaDH--aol--com] wrote:
>>if length? tlist/data > 1000
>
> Try these:
>
> if (length? tlist/data) > 1000
> or
> if 1000 <= length? tlist/data
>
> (I always go for the (...) solution as I can't be bothered with reversing
> boolean operations.
>
I've been experimenting lately with restricting myself to using only
< and <= to express ordered comparisons. There were a couple of initial
reasons for the experiment:
- as the number line (conventionally pictured, anyway!) contains smaller
values on the left and larger values on the right, I wanted to test
the mnemonic value of writing expressions with smaller/left and
larger/right ordering;
- it gives compound and range conditions a natural form:
... all [lowerlimit <= testvalue testvalue <= upperlimit] ...
which resembles the normal mathematical notation:
lowerlimit <= testvalue <= upperlimit
(the only languages I can recall at the moment that understand that
notation would be Python and Icon).
- it's an interesting psychological experiment; mathematically the two
expressions (e.g.)
a < b
and
b > a
are equivalent, so why is it that so many of us have learned to
feel more comfortable with
foo > 100
than
100 < foo
in our programs? Is it because our "natural language" habits make
us subconsciously think of the expresson(s) above as being more
about FOO as the subject of the sentence, rather than about the
relationship between two equally-important values?
At any rate, it also has the interesting side effects that many REBOL
expressions no longer need parentheses. It's also interesting to see
the effect on one's thinking from deliberately breaking almost sub-
conscious habits.
-jn-
