From: pjb@... (Pascal J. Bourguignon)
Date: 2009-01-13T15:54:15+09:00
Subject: Re: functional programming

Mike Gold <mike.gold.4433@gmail.com> writes:

> The topic was about the problems arising from the syntactic difference 
> between methods and lambdas.  You've changed gears to a generic 
> discussion about procs.  My question is yet unaddressed: why is 
> func.call() or func[] or func.() "very useful" compared to func()?  As I 
> mentioned, in every case I've found it to be a hassle, for the reasons 
> previously stated.

The reason is because Ruby is a lisp-2.  The same name can be used to
designate both a method and a variable.  So you need two syntaxes, to
make reference to the method of a name, or to the variable.  When the
variable contains normal values, 

(def f 
   :function
end)

f = (lambda { :variable })


irb(main):064:0> [ f , (f []) , (method :f) , (f ()) ] 
[ f , (f []) , (method :f) , (f ()) ] 
[#<Proc:0x00306ed4@(irb):51>, :variable, #<Method: Object#f>, :function]



In Common Lisp, which is a lisp-2 too, we use FUNCALL to call functions
stored in variables: 

(defun f () :function)
(defvar f (lambda () :variable))

C/USER[24]> (list f (funcall f) (function f) (f))
(#<FUNCTION :LAMBDA NIL> :VARIABLE #<FUNCTION F NIL> :FUNCTION)


-- 
__Pascal Bourguignon__