On Fri, May 31, 2013 at 4:42 PM, Ryan Culpepper wrote:
>
> Note, however, that the syntax class now uses #:attr instead of #:with.
> That's the main usability issue I'm worried about with this change.
> Following with-syntax's lead, a #:with clause automatically converts its
> right-hand side to s
On 05/31/2013 02:47 AM, Eric Dobson wrote:
I'm working on code (TR optimizer) that needs to match some
expressions and then compute an attribute based on the expression. I
would like to abstract this out as a syntax class. Example is below:
#lang racket
(require syntax/parse)
(define-syntax-cla
This might answer some of your questions:
http://macrologist.blogspot.com/2011/09/syntax-parse-and-literals.html
Ryan
On 05/31/2013 02:30 AM, Eric Dobson wrote:
Ok given the complexities of literal-sets and hygiene, I think I will
avoid them if I can. The issue is that I cannot seem to get th
You would have to implement laziness for attributes manually -- I think.
But I don't have time to play with code and get an example to work right
now. -- Matthias
On May 31, 2013, at 11:00 AM, Eric Dobson wrote:
> That seems like a a workable amount of overhead, but I'm not sure what
> you ar
That seems like more syntax in the use than just #`(complicated
#,((attribute e.v))), which I can get with just thunking the
computation. The thunk it self can manipulate a promise to make sure
the effects only happen once.
I'm pretty sure I could use a rename transformer struct property and a
cha
You could also make a compile-time macro that will introduce several identifier
macros to your syntax-class pattern right-hand-sides like
(define-lazy-syntax-class blah
(pattern pat #:lazy-wrap [complicated (e.v ...)] rhs ...) ...)
=>
;; generate ((force-e.v ...) ...)
(define-syntax-class bla
That seems like a a workable amount of overhead, but I'm not sure what
you are suggesting the v attribute to be bound as. It might have not
been obvious from my my example that its value depends on the slow
computation, so unless pattern variables can be mutated I'm not sure
how force-all can chang
Can you prefix the #'(complicated ..) expression with a form
that forces all lazy computations so that complicated itself
remains the same?
(let () (force-all) #'(complicated (form e.v)))
where force-all is defined via a begin in the slow syntax class?
-- Matthias
On May 31, 2013, at 2:4
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