Interesting: "Lisp as a competitive advantage"
Thu, 3 May 2001 16:25:45 -0400 (EDT)
(Drat. Sorry for the duplicate message. I just learned a new Emacs
keystroke by accident... Ever notice how you never make a mistakes like
that unless the audience is very large?)
Subject: Re: Interesting: "Lisp as a competitive advantage"
Date: Thu, 03 May 2001 10:16:37 -0400
From: Norman Ramsey <firstname.lastname@example.org>
When I compare Lisp and Haskell, the big question in my mind is this:
is lazy evaluation sufficient to make up for the lack of macros?
I would love to hear from a real Lisp macro hacker who has also done
lazy functional progrmaming.
The answer is: "almost". Simply having higher order functions eliminates a
lot of the need to macros. Common Lisp programmers could probably use a
lot fewer macros than they do in practice. Lazy evaluation eliminates
the need for another pile of macros. But there are still things you
need macros for.
Here's a macro I use in my Scheme code all the time. I write:
(assert (< x 3))
Which macro expands into:
(if (not (< x 3))
(assertion-failed '(< x 3)))
Where `assertion-failed' is a procedure that generates an appropriate error
message. The problem being solved here is getting the asserted expression
into that error message. I don't see how higher order functions or lazy
evaluation could be used to write an `assert' that behaves like this.