racket/collects/web-server/scribblings/closure.scrbl

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1.7 KiB
Racket

#lang scribble/doc
@(require "web-server.rkt")
@title[#:tag "closure"]{Serializable Closures}
@(require (for-label racket/serialize
web-server/lang/closure
web-server/lang/serial-lambda
web-server/private/define-closure))
The defunctionalization process of the Web Language (see @secref["stateless" #:doc '(lib "web-server/scribblings/web-server.scrbl")])
requires an explicit representation of closures that is serializable.
@defmodule[web-server/lang/serial-lambda]{
@defform[(serial-lambda formals body ...)]{
Returns @racket[(lambda formals body ...)], except it is serializable.
}
@defform[(serial-case-lambda [formals body ...] ...)]{
Returns @racket[(case-lambda [formals body ...] ...)], except it is serializable.
}
}
@section[#:style 'hidden]{Definition Syntax}
@defmodule[web-server/private/define-closure]{
@defform[(define-closure tag formals (free-var ...) body)]{
Defines a closure, constructed with @racket[make-tag] that accepts a closure that returns
@racket[freevar ...], that when invoked with @racket[formals]
executes @racket[body].
}
Here is an example:
@racketmod[
racket
(require racket/serialize)
(define-closure foo (a b) (x y)
(+ (- a b)
(* x y)))
(define f12 (make-foo (lambda () (values 1 2))))
(serialize f12)
#,(racketresult '((1) 1 (('page . foo:deserialize-info)) 0 () () (0 1 2)))
(f12 6 7)
#,(racketresult 1)
(f12 9 1)
#,(racketresult 10)
(define f45 (make-foo (lambda () (values 4 5))))
(serialize f45)
#,(racketresult '((1) 1 (('page . foo:deserialize-info)) 0 () () (0 4 5)))
(f45 1 2)
#,(racketresult 19)
(f45 8 8)
#,(racketresult 20)
]
}