On 2/29/2012 9:09, Xah Lee wrote:
New Science Discovery: Perl Idiots Remain Idiots After A Decade!
A excerpt from the new book 〈Modern Perl〉, just published, chapter 4
on “Operators”. Quote:
«The associativity of an operator governs whether it evaluates from
left to right or right to left. Addition is left associative, such
that 2 + 3 + 4 evaluates 2 + 3 first, then adds 4 to the result.
Exponentiation is right associative, such that 2 ** 3 ** 4 evaluates 3
** 4 first, then raises 2 to the 81st power. »
LOL. Looks like the perl folks haven't changed. Fundamentals of
serious math got botched so badly.
Let me explain the idiocy.
It says “The associativity of an operator governs whether it evaluates
from left to right or right to left.”. Ok, so let's say we have 2
operators: a white triangle △ and a black triangle ▲. Now, by the
perl's teaching above, let's suppose the white triangle is “right
associative” and the black triangle is “left associative”. Now, look
at this:
3 △ 6 ▲ 5
seems like the white and black triangles are going to draw a pistol
and fight for the chick 6 there. LOL.
Sorry, but you're wrong and they're right.
Associativity governs the order of evaluation of a group of operators
*OF THE SAME PRECEDENCE*.
If you write
2**3**4
only the fact the '**' is right associative will tell you that the order is
2**(3**4)
and not
(2**3)**4
I remind you that 2^(3^4) != (2^3)^4.
Kiuhnm
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