From: Trans <transfire@...>
Date: 2005-11-02T00:57:07+09:00
Subject: Re: Anonymous methods, blocks etc. (Cont. 'default block params')

This is abit to the side, but maybe it would shed light on the
discussion. I'm wondering why lambda's can't be like more methods. If I
define a method:

  def meth ; 1 ; end

and then type

  meth  #=> 1

The output is immediate, 1. But with a lambda, i.e. an aynnomous
method, this is not the case.

  lam = lambda do ; 1 ; end
  lam #=> #<Proc...>

To get hold of a first class method we have to do method(:meth). Many
of us have wanted something briefer (of course this ties into the whole
UnboundMethod/Method/Lambda/Proc/Block craziness, nontheless...) So why
not have the two on the same footing then?

  lam = lambda do ; 1 ; end
  lam #=> 1

And to get a reference to the actual lambda object maybe

  &lam

and we can do it for methods:

  &meth  #or &self.meth as the case may warrent

I know that usually turns a lambda into a block, but in essense isn't
that the same thing? Well if not then use another symbol. The important
thing is now its clean and much more useful. We can actually drop in
lambdas for local vars without perceptable difference. Very cool! Very
useful!

Okay, so how does this get back to the case at hand. Interestingly it
would mean:

  def x ; 1 ; end

and

  x = lambda do ; 1 ; end

mean almost the same thing, except for two distinctions: 1) the lambda
has closure, and 2) the lamda's x is a local var, while the def's x is
on the instance level, like @x. And that's very interesing b/c that
means

  def initialize
    @x = lambda do ; 1 ; end
  end

@x is like having a local instance method!

It also indicates that #def is like a method taking a special parameter
'x' --just like define-method:

  def( :x ) do ; 1 ; end

So I think it's reasonable to deem that if that parameter is not given
then it is annonymous so:

  x = def() do ; 1 ; end

This is very much like what Dave suggested. And like him this def I
imagine this should be *non-closure*. And we need another name for
closure, that could be 'lambda', okay, but I'd prefer somthing shorter,
like 'fn' or maybe with three letters like 'def' so maybe 'dfn'

  x = dfn do ; 1 ; end

Of course these are special and should be keywords so then we can drop
the 'do'. The only thing that sets them a part from other methods is
that with 'def' a special parameter can appear in the front of the
parameters to define an instance level name, i.e. the method name. I
suppose the same can be done for dfn is we want to keep the closure.

  class X
    name = self.name
    dfn x ; name ; end
  end

  X.new.x  #=> "X"

I think that solves just about all the signifficant issues related to
this. If Matz want's an '->' operator to basically mean 'dfn', that's
his call, but I think maybe most people will be happier with a word
form.

Sorry to go on so long, but I HTH.
T.