From: Elliot Temple <curi@...>
Date: 2006-08-26T04:51:27+09:00
Subject: Re: and and or priority


On Aug 25, 2006, at 12:38 PM, Alex Young wrote:

> Pavel Smerk wrote:
>> OMG!
>> Why the and and or operators have the same priority? Unlike && and  
>> || and also unlike the most of, or maybe all, other languages and  
>> conventions?
> Good question.
>
> irb(main):001:0> true and false or true and false
> => false
>
> tells me that and binds tighter than or, unless something unobvious  
> is going on, which might well be...
>
> Have you got a counterexample handy?

irb(main):008:0> true or true and false
=> false

If "and" had higher priority, that'd evaluate as:

true or true and false
true or false
true

I think it's going left to right:

true or true and false
true and false
false

Pickaxe page 339 says they have the same priority and calls them  
"logical composition" operators.

As to the OP's question: I don't know why.

-- Elliot Temple
http://www.curi.us/blog/