[racket] Formal Presentation and initial doubts.

> Does... CL have a pattern-based macro syntax like syntax-rules?

Not buit-in.

> If not, it seems surprising to argue that lisp macros would be easier to
learn. Can you give examples?

The explanation of CL macros and their application in On
Lisp<http://www.bookshelf.jp/texi/onlisp/onlisp.html> seems
more accessible, for example, than anything I've been able to lay my hands
on for the syntax-rules/case/parse.

Dan



On Sat, Mar 22, 2014 at 10:28 AM, John Clements
<clements at brinckerhoff.org>wrote:

>
> On Mar 21, 2014, at 3:49 PM, Daniel Prager <daniel.a.prager at gmail.com>
> wrote:
>
> > Thank-you for raising this topic.
> >
> > > I don't understand well its macros (are completely different for me
> than CL macros).
> >
> > Me neither. And I'm somewhat torn. The trade-off as I understand it is
> that CL-style macros are *much* easier to learn, but prone to aliasing
> while hygenic macros are technically superior because they compose better
> and you can't accidentally hit aliasing problems. But when it comes to
> learning, the advantages are reversed.
>
> Does... CL have a pattern-based macro syntax like syntax-rules? If not, it
> seems surprising to argue that lisp macros would be easier to learn. Can
> you give examples?
>
> John Clements
>
> >
> > William Byrd, in this 2012 interview with Michael Fogus, comments on
> some of these issues:
> > Clojure's macro system appears to me to be a kludge, trying to patch up
> Common Lisp's defmacro without going all the way to real hygienic macros. I
> don't mean to be overly critical--I'm not happy with the state of Scheme,
> either, which has not one but two hygienic macro systems, neither of which
> is ideal.
> >
> > The more powerful Scheme macro system, syntax-case, gives the programmer
> the full power of Scheme at macro expansion time, along with the ability to
> "bend" hygiene when desired. Syntax-case is powerful enough to define
> Common Lisp's defmacro (and almost certainly powerful enough to define
> Clojure's defmacro as well). Unfortunately, syntax-caseis notoriously
> complicated. As far as I can tell, mastering syntax-case requires a mental
> model equivalent in complexity to the macro expander's implementation. As a
> result, Dan, Oleg, and I refuse to use syntax-case.
> >
> > The other Scheme macro system, syntax-rules, is strictly less powerful
> than syntax-case, and can in fact be implemented in syntax-case. However,
> the mental model required to use syntax-rules is much simpler, as it is
> essentially a term-rewriting system with hygiene. For vanilla forms such as
> let, and, and or, syntax-rules works beautifully. For incredibly
> complicated macros, such as the match pattern matcher used in Kent Dybvig's
> compiler course at Indiana, the full power of syntax-case is probably
> required. For almost all other macros, it seems like a system with just a
> little more power than syntax-rules would be both sufficient and ideal. For
> example, often a macro writer wishes to concatenate two symbols--currently
> this requires using syntax-case, even if the rest of the macro is trivial.
> >
> > If a hygienic macro system that hits the sweet spot between syntax-rules
> and syntax-caseis created, I hope it will be adopted by Schemers and
> Clojurers alike. A few steps in this direction include the Dylan macro
> system and Ryan Culpepper's syntax-parse. Also needed is a way to learn how
> to write non-trivial hygienic macros that doesn't involve earning a PhD in
> programming languages from Indiana or Northeastern.
> >
> > The Racket and Scheme inner circle say that hygienic macros are the
> future, but I wonder whether a worse-is-better argument can be mounted for
> CL and/or Clojure macros.
> >
> > Personally, I only write Racket macros sparingly, but would like to
> develop my level of understanding of comfort.
> >
> > What are some good ways to smooth out the learning curve?
> >
> >
> > Dan
> >
> >
> >
> > On Sat, Mar 22, 2014 at 12:42 AM, Matthias Felleisen <
> matthias at ccs.neu.edu> wrote:
> >
> > Welcome.
> >
> > Why don't you take a look at Greg's macro write-up
> >
> >  http://www.greghendershott.com/fear-of-macros/
> >
> > and see whether this helps you wrap your head around macros.
> >
> >
> >
> >
> > On Mar 21, 2014, at 9:48 AM, Alejandro Zamora Fonseca <terefv at ltu.sld.cu>
> wrote:
> >
> > > Hi!!
> > > My name is
> > > Alejandro, i'm a Cuban Computer Scientist, new to Lisp(having 1 year
> using CL), and wishing change to Racket.
> > > I see the list and I hope make me a better Lisp programmer with your
> kindly help.
> > >
> > > I have Racket installed in my PC, I like the language and tools, but
> yet I don't understand well its macros(are completely different for me than
> CL macros) and continuations.
> > >
> > > Greetings for all.
> > >
> > > Alejandro
> > >
> > >
> > >
> > >
> > > --
> > >
> > > Este mensaje le ha llegado mediante el servicio de correo electronico
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> establecidas
> > >
> > > Infomed: http://www.sld.cu/
> > >
> > > ____________________
> > > Racket Users list:
> > > http://lists.racket-lang.org/users
> >
> >
> > ____________________
> >   Racket Users list:
> >   http://lists.racket-lang.org/users
> >
> >
> >
> > --
> > Daniel Prager
> > Agile/Lean Coaching, Software Development and Leadership
> > Startup: www.youpatch.com
> > Twitter: @agilejitsu
> > Blog: agile-jitsu.blogspot.com
> > ____________________
> >  Racket Users list:
> >  http://lists.racket-lang.org/users
>
>


-- 
*Daniel Prager*
Agile/Lean Coaching, Software Development and Leadership
Startup: www.youpatch.com
Twitter: @agilejitsu <https://twitter.com/agilejitsu>
Blog: agile-jitsu.blogspot.com
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