On the subject of porting #lang racket to #lang web-server code
I provide a few lessons learned for the archives for the next person to
attempt this.
1) Bindings, Serializability , and anonymous functions
1A) the predicate serializable? from racket/serializable is invaluable
#lang web-server code will not transform if there are non-serializable
constructs in the dynamic extent of the invocation of send/suspend
some minor surprises/lessons learned:
1B) anonymous functions are not serializable
(serializable? (λ (x) x)) ;->#f
1C) anonymous functions in a list are not serializable
(serializable? (car (list (λ (x) x) (λ (x) x)))) ;->#f
1D) once given a module-level binding, anonymous functions become
serializable
(define foo (list (λ (x) x) (λ (x) x)))
(serializable? (car foo)) ;->#t
1E) void is not serializable
(serializable? void) ;->#f
1F) anonymous functions bound within a letrec form are serializable
2) 'attempt to cross a continuation barrier' exceptions
invocations of native continuations reified with call/cc seemed to
frequently throw this error
I haven't done enough analysis to understand why and under what
conditions, but in all cases I was able to remediate by enclosing the
invocation as follows.
(call-with-continuation-prompt k (default-continuation-prompt-tag)
3) with-continuation-marks, continuation-marks, and
current-continuation-marks can be used to replace dynamic-wind
Again, thank you. I think the stateless web-language is important
technology and must have required an enormous amount of work to
implement.
Anedcotally, application speed seems at or better than the stateful
code.
R./
Zack
On Sun, Jan 1, 2012 at 4:36 PM, Jay McCarthy wrote:
On Sat, 31 Dec 2011 20:03:02 -0600,Robby Findler
<ro...@eecs.northwestern.edu> mumbled:
I'm not sure if the web-server supports continuation marks or not
The stateless transformation does support continuation marks, provided
the keys and values are serializable. (Parameters/exception handlers
are not supported because the key is not serializable.)
Jay
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