| I've been wondering if it's possible to use the
Arc-style of web application development with Google
App Engine. [By the way, is there a name for this
style of web development?] I already have Jarc running on App Engine, but how
to deal with the closures? Since a compiler can
find all the closed-over variables, it should be
possible to syntactically transform: (defop hello req
(let name "Chris"
(w/link (pr "hello there, " name)
(pr "here"))))
into something like: (def /hello (req)
(let name "Chris"
(setAttribute req!Session "name" name)
(a href '/g17 (pr "here"))))
(def /g17 (req)
(pr "hello there, " (getAttribute req!Session "name")))
With intermediate functions this gets much harder. News
does something similar to this: (defop h1 req
(let x 12
(h2 (fn (req) ... x))))
(def h2 (f)
(taform nil
(fn (req) ... (f req))))
Now I can't just do a syntatic rewrite. I'd need
either:1) A function that takes a closure and returns the
list of closed-over variables and their values.
Then taform could find that the closure it gets
passed is closed over f. And then find out that f is
a closure and it is closed over x. Then it could
add the appropriate setAttribute calls. AND 1b) A way to change the closure code to replace x
with (getAttribute req!Session "x") OR 2) A way to serialize (and unserialize) closures. I think #2 would be easier to add to Jarc. At
closure time, just find all the free variables that
are bound in the current environment. Then the
serialized form is something like: (let name "Chris"
(fn (req) (pr "hello there, " name)))
Or in the more complicated example: (let f (let x 12 (fn (req) ... x))
(fn (req) ... (f req)))
I'm not sure this is worth the effort, but does this
seem like it would work? Or am I missing something? | 
