From: Nick Sabalausky <hmcfryxhbmyac@...>
Date: 2010-03-03T10:36:02+09:00
Subject: Re: Here's a filtered file/dir copy, FWIW.

Ryan Davis wrote:
> On Mar 2, 2010, at 11:12 , Nick Sabalausky wrote:
> 
>> Soapbox on terminology: Though these terms *frequently* get mixed up, 
>> "closure" merely refers to the ability of code to access locals from the 
>> function it's defined within regardless of whether or not that enclosing 
>> function has returned (And yes, Ruby's closures fit this definition, or 
>> at least as far as I can tell).
> 
> Wow. Thanks for the attitude after helping you with your problem. Maybe 
> I should have focused on "like I was expecting it to be" and pointed out 
> that studying one's language is tantamount to success.
> 

There was no attitude intended. In fact, I deliberately overlooked what 
I saw as attitude in "And again, you need to ACTUALLY write tests. 
/soapbox".

> Soapbox on history:
> 
> Maybe you should look at (real) programming languages like smalltalk, 
> commonlisp, or scheme. Ruby bases a lot of its semantics on languages 
> like lisp and smalltalk. The following wikipedia entry has code samples 
> of each (and ruby and many others) describing exactly this problem.
> 
>    http://en.wikipedia.org/wiki/Closure_(computer_science)
> 

This snippet is very helpful:

------
def bar
  f = lambda { return "return from lambda" }
  f.call # control does not leave bar here
  return "return from bar"
end

puts bar # prints "return from bar"
------

I was not aware of that alternate form of ruby closure.

>> But, "closure" does *not* imply that it isn't a function - in fact, in 
>> most languages, closures *are* full-fledged functions that are, 
>> depending on the language, created with either nested functions and/or 
>> anonymous function literals. I've dealt with closures in plenty of 
>> different languages and this is still the first one I've come across 
>> where returning from a closure also returned from the function that 
>> invoked the closure and all the way down the stack through the function 
>> it was created within. So no, that's not how closures necessarily work.
> 
> Not only did I _not_ imply that a closure isn't a function, I didn't 
> imply that ruby blocks were not functions (or methods).

Then there's no need to take it personally. :)
-- 
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