From: Nicholas Van Weerdenburg <nick@...>
Date: 2004-07-18T23:29:45+09:00
Subject: Re: other meanings of ( and ) aka Lispy usage

I think "statement grouping" clears it up for me. I guess in another 
way,  () act as a form of block- you could even think of method 
parameters as another type of block being passed to a method. {} is 
syntactic sugar to define a second block being passed as a higher-order 
function/closure (with the additional parameter passing/yield capability).

{|x| do x}  -->  (lamba (|x| do x))  
or something like that.

Thanks,
Nick

Mark Hubbart wrote:

>
> On Jul 17, 2004, at 8:45 PM, Nicholas Van Weerdenburg wrote:
>
>> What's the meaning of ()  outside of being function parameter 
>> delimiters aka in a Lispy sense?
>> e.g.
>> (puts "command=" + (command="vi " + filename))
>>
>> Obvious + is actual a method, so that explains the () around 
>> "command=", but there is the () around the entire line.
>
>
> First, there is the expression grouping. That is what lets you say (23 
> + 42) * 69, or (Math.sqrt 23) + 42, or even ("this" + "that").display
>
> Then, function parameter delimeters. These are, of course, mostly 
> optional in ruby. STDERR.puts("Yoiks!", "Stop that!")
>
> Parens can also act as statement groupings. Multiple statements can be 
> collected into one expression, where the value of the expression -- 
> everything inside the parens -- is given the value of the last 
> statement. So, you can do things like this (warning! very contrived):
>
>   baz = ((foo=23; bar=foo+7; bar*foo) if condition)
>
> In this, if condition is true, foo is set to 23, bar is set to 30, and 
> the parenthetical expression returns a value of 23*30. baz will be set 
> to 690. If condition is false, nothing else is evaluated, and baz is 
> set to nil.
>
> I hope the last part wasn't more confusing than helpful... :/
>
> HTH,
> Mark
>
>