181 lines
6.6 KiB
Racket
181 lines
6.6 KiB
Racket
#lang scribble/manual
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@(require (for-label racket
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syndicate/actor))
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@title{High Level Syntax for Syndicate}
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@defmodule[syndicate/actor]
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@section{Instantaneous Actions (I)}
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@defform[(actor I ...)]{
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Spawns an actor that executes each instantaneous action @racket[I] in
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sequence.}
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@defform[(dataspace I ...)]{
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Spawns a dataspace as a child of the dataspace enclosing the executing actor. The
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new dataspace executes each instantaneous action @racket[I].}
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@defproc[(send! [v any/c]
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[#:meta-level level natural-number/c 0])
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void?]{
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Sends a message with body @racket[v]. The message is sent @racket[level]
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dataspaces removed from the dataspace containing the actor performing the
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@racket[send!].}
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@defproc[(assert! [v any/c]
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[#:meta-level level natural-number/c 0])
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void?]{
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Asserts the value of @racket[v] until either explicitly retracted via
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@racket[retract!] or the immediately enclosing actor exits. @racket[level]
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specifies which dataspace the assertion should be made, in terms of relative
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distance from the dataspace containing the enclosing actor.}
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@defproc[(retract! [v any/c]
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[#:meta-level level natural-number/c 0])
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void?]{
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Retracts any assertions made by the immediately enclosing actor at
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@racket[level] dataspaces above the enclosing dataspace of the form @racket[v].}
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@section{Ongoing Behaviors (O)}
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@defform[(state maybe-init (maybe-bindings O ...) ([E I ...] ...))
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#:grammar
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[(maybe-init (code:line)
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(code:line #:init [I ...]))
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(maybe-bindings (code:line)
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(code:line #:collect ([id init] ...)))]
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#:contracts ([id identifier?])]{
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Spawns a new actor with ongoing behaviors @racket[O ...] that runs until a
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termination event is detected.
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The optional @racket[#:init [I ...]] provides a sequence of initialization
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actions. The initial actions are executed before the ongoing behaviors begin but
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after the interests of the state actor are established.
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The optional @racket[#:collect [(id init) ...]] clause introduces bindings that
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are visible within the body of the state actor. Each binding @racket[id] is
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initialized to the corresponding @racket[init] expression. The bindings are
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updated when an ongoing behavior executes an instantaneous event, such as the
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result of an @racket[on] behavior. The new bindings are in the form of a
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@racket[values] form, with the new values in the same order and number as in the
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@racket[#:collect].
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The ongoing behaviors @racket[O ...] are run simultaneously until the state
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actor exits.
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Each @racket[[E I ...]] specifies a termination event @racket[E] of the actor.
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When a termination event @racket[E] activates, the corresponding @racket[I]s are
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executed. The state actor then exits, with the same result of the final
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@racket[I] action.}
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@defform[(until E
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maybe-init
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maybe-bindings
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maybe-done
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O ...)
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#:grammar
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[(maybe-init (code:line)
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(code:line #:init [I ...]))
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(maybe-bindings (code:line)
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(code:line #:collect ([id init] ...)))
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(maybe-done (code:line)
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(code:line #:done [I ...]))]
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#:contracts ([id identifier?])]{
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An @racket[until] behavior corresponds to a @racket[state] behavior with only
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one termination event, given by @racket[E]. The final result of the
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@racket[until] behavior is the values of the @racket[#:collect] bindings in
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scope from any parent actors followed by the final values of the @racket[until]
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actor's bindings. The actions in a @racket[#:done] clause are executed after the
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termination event but before the @racket[until] actor exits.}
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@defform[(forever maybe-init
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maybe-bindings
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O ...)
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#:grammar
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[(maybe-init (code:line)
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(code:line #:init [I ...]))
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(maybe-bindings (code:line)
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(code:line #:collect ([id init] ...)))]
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#:contracts ([id identifier?])]{
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The @racket[forever] behavior is analogous to a @racket[state] form with no
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termination events.}
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@defform[(during pat O ...)]{
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Runs the behaviors @racket[O ...] for the duration of each assertion matching
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@racket[pat].
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Roughly equivalent to
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@racket[(on (asserted pat)
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(until (retracted pat)
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O ...))]
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where the @racket[pat] in the @racket[until] clause is specialized to the actual
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value matched by @racket[pat] in the @racket[asserted] clause.
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}
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@defform[(assert maybe-pred exp maybe-level)
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#:grammar
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[(maybe-pred (code:line)
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(code:line #:when pred))
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(maybe-level (code:line)
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(code:line #:meta-level level))]
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#:contracts ([pred boolean?]
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[level natural-number/c])]{
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Makes the assertion @racket[exp] while the enclosing actor is running. If a
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@racket[#:when] predicate is given, the assertion is made conditionally on the
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predicate expression evaluating to true.}
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@defform[(on E
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I ...)]{
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When the event @racket[E] becomes active, executes the instantaneous actions
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@racket[I ...] in the body. The result of the final action is the result of the
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entire behavior.}
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@section{Events (E)}
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@defform[(message pat)]{
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Activates when a message is received with a body matching @racket[pat].
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The message event establishes the enclosing actor's interest in @racket[pat].}
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@defform[(asserted pat)]{
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Activates when a patch is received with an added assertion matching
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@racket[pat]. Establishes the enclosing actor's interest in @racket[pat].}
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@defform[(retracted pat)]{
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Similar to @racket[asserted], except for assertions removed in a patch.}
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@defform[(rising-edge expr)]{
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Activates when @racket[expr] evaluates to anything besides @racket[#f] (having
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previously evaluated to @racket[#f]). The condition is checked after each
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received event, corresponding to after each instantaneous action is executed.}
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@section{Patterns}
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@(racketgrammar
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pat
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(code:line)
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(code:line _)
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(code:line $id)
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(code:line ($ id pat))
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(code:line (? pred pat))
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(code:line (ctor pat ...))
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(code:line expr))
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@racket[_] matches anything.
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@racket[$id] matches anything and binds the value to @racket[id].
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@racket[($ id pat)] matches values that match @racket[pat] and binds the value
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to @racket[id].
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@racket[(? pred pat)] matches values where @racket[(pred val)] is not
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@racket[#f] and that match @racket[pat].
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@racket[(ctor pat ...)] matches values built by applying the constructor
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@racket[ctor] to values matching @racket[pat ...].
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@racket[expr] patterns match values that are exactly equal to @racket[expr].
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