From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-07-26T12:17:02+09:00
Subject: Re: Lisp on Lines

On Tue, 26 Jul 2005, Devin Mullins wrote:

> zak.wilson@gmail.com wrote:
>
>> This looks like first class functions to me:
>> 
>> def accgen (n)
>>  lambda {|i| n += i }
>> end
>> 
>> foo = accgen(5)
>> foo.call(5) # returns 10
>> foo.call(5) # returns 15
>> 
>> accgen function borrowed from http://www.paulgraham.com/accgen.html
>> 
> Perhaps we need a new term. According to Google, "First class hooberglobbers" 
> seems to mean hooberglobbers can be assigned to variables, parameters, and 
> return values, and then, though the assignee, can be manipulated in all the 
> ways that hooberglobbers can be manipulated. Under this definition, yes, Ruby 
> has first class functions.
>
> I have a stricter definition. Let's call it "patrician hooberglobbers." 
> Patrician hooberglobbers, to me, have the additional quality that the syntax 
> for manipulating a hooberglobber is the same whether it is referred to 
> statically or by evaluation/substitution (as through a variable, or return 
> value of a function call). In this sense, Ruby has patrician classes:
>
> a = String.new
> b = String
> c = b.new
>
> However, while Lisp, Python (from the examples I've seen), and Unlambda have 
> patrician functions, Ruby does not. I can think of two simple enough reasons 
> for this:
>
> 1. Because Ruby has a "poetry mode," there is no way to refer to a function 
> by reference -- simply referring to it invokes it. The closest you can get is 
> to refer to the Symbol representing its name, or to create a Method object, 
> which really just wraps an invocation of the method inside a class.

   harp:~ > irb
   irb(main):001:0> a = lambda{ p 42 }
   => #<Proc:0xb755d848@(irb):1>

   irb(main):002:0> a ()
   42
   => nil

   irb(main):003:0> a()
   42
   => nil

   irb(main):004:0> b = a
   => #<Proc:0xb755d848@(irb):1>
   irb(main):005:0> b()
   42
   => nil

   harp:~ > ruby -v
   ruby 1.9.0 (2005-05-16) [i686-linux]

   harp:~ > irb -v
   irb 0.9.5(05/04/13)


getting pretty close...

cheers.

-a
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