From: Jim Weirich <jweirich@...>
Date: 2003-02-15T08:50:31+09:00
Subject: Re: Lexical scope and closures

On Fri, 2003-02-14 at 05:11, Robert Klemme wrote:
> > Matz [mailto:matz@ruby-lang.org] wrote kindly:
> >
> > >   arr.each {|i|
> > >     let a = ..
> > >     let b = ..
> > >     c = ..
> > >     ...
> > >   }
> >
> > <grin> I like this, reminds me of basic. Or maybe ":=" wc reminds me of
> > pascal :-)
> 
> I remindes me more of the lisp 'let' - and I think this was intended. :-)

Actually, to me, it is the "local" command that reminds me of the
Lisp-ish let (despite the names).  In Lisp (IIRC) "let" is a macro that
expands into a lambda form with the variables as formal arguments in the
lambda.  This is exactly what the "local" method is doing.  In fact, I
recall the Lisp "let" macro allows initial values to be specified as
well.  To make the analogy complete, we could do ...

   arr.each {|i|
     local(2*i, i**2) { |a, b|
       # a is initialized to 2*i
       # b is initialized to i**2
     }
   }

-- 
-- Jim Weirich     jweirich@one.net    http://w3.one.net/~jweirich
---------------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct, 
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)