From: Sylvain Joyeux <sylvain.joyeux@...>
Date: 2006-10-28T22:02:04+09:00
Subject: Re: What are closures, continuations?

> The lambda calculus took it from the Greek Alphabet, who adapted it
> from the Phoenecian Alphabet, and so on (you could keep going
> forever). Actually closures are never called "lambdas", at least not
> in any writing I've read on Lisp, it's just a symbol used to denote a
> closure.
A lambda is not necessary a closure. A lambda is an anonymous function (and 
as you will see later, this is *not* a block or a Proc.new { ... })

The meaning of the lambda operator in languages like Ruby is "build an 
anonymous function", and it does come from lambda calculus. Lambda (in 
Ruby) is building a function (actually, a Proc) from a block. 
The "closure" part comes from the fact that blocks are closures. If blocks 
weren't closures, lambdas would not be either.

Calling 'return' in Proc.new { return }.call fails with LocalJumpError 
while it works in lambda { return }.call . Kernel#lambda really changed 
the block into a function.

My 2 cents
-- 
Sylvain Joyeux