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renamed world to iworld, for internal

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svn: r13588
This commit is contained in:
Matthias Felleisen 2009-02-15 01:11:24 +00:00
parent 203ba8e2db
commit 4f24983d29
1 changed files with 40 additions and 41 deletions
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81
collects/teachpack/2htdp/scribblings/universe.scrbl
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@ -906,41 +906,41 @@ Understanding the server's event handling functions demands several data
data representation of the @tech{world}s that participate in the
universe.
@defproc[(world? [x any/c]) boolean?]{
determines whether @scheme[x] is a @emph{world}. Because the universe server
@defproc[(iworld? [x any/c]) boolean?]{
determines whether @scheme[x] is a @emph{iworld}. Because the universe server
represents worlds via structures that collect essential information about
the connections, the teachpack does not export any constructor or selector
functions on worlds.}
@defproc[(world=? [u world?][v world?]) boolean?]{
compares two @emph{world}s for equality.}
@defproc[(iworld=? [u iworld?][v iworld?]) boolean?]{
compares two @emph{iworld}s for equality.}
@defproc[(world-name [w world?]) symbol?]{
extracts the name from a @emph{world} structure.}
@defproc[(iworld-name [w iworld?]) symbol?]{
extracts the name from a @emph{iworld} structure.}
@defthing[world1 world?]{a world for testing your programs}
@defthing[world2 world?]{another world for testing your programs}
@defthing[world3 world?]{and a third one}
@defthing[iworld1 iworld?]{an @emph{iworld} for testing your programs}
@defthing[iworld2 iworld?]{another iworld for testing your programs}
@defthing[iworld3 iworld?]{and a third one}
The three sample worlds are provided so that you can test your functions
The three sample iworlds are provided so that you can test your functions
for universe programs. For example:
@schemeblock[
(check-expect (world=? world1 world2) false)
(check-expect (world=? world2 world2) true)
(check-expect (iworld=? iworld1 iworld2) false)
(check-expect (iworld=? iworld2 iworld2) true)
]
}
@item{Each event handler produces a @emph{bundle}, which is a structure
that contains the list of @emph{world}s to keep track of; the
that contains the list of @emph{iworld}s to keep track of; the
@tech{server}'s remaining state; and a list of mails to other
worlds:
@defproc[(bundle? [x any/c]) boolean?]{
determines whether @scheme[x] is a @emph{bundle}.}
@defproc[(make-bundle [low (listof world?)] [state any/c] [mails (listof mail?)]) bundle?]{
creates a @emph{bundle} from a list of worlds, a piece of data that represents a server
@defproc[(make-bundle [low (listof iworld?)] [state any/c] [mails (listof mail?)]) bundle?]{
creates a @emph{bundle} from a list of iworlds, a piece of data that represents a server
state, and a list of mails.}
A @emph{mail} represents a message from an event handler to a world. The
@ -949,8 +949,8 @@ teachpack provides only a predicate and a constructor for these structures:
@defproc[(mail? [x any/c]) boolean?]{
determines whether @scheme[x] is a @emph{mail}.}
@defproc[(make-mail [to world?] [content sexp?]) mail?]{
creates a @emph{mail} from a @emph{world} and an @tech{S-expression}.}
@defproc[(make-mail [to iworld?] [content sexp?]) mail?]{
creates a @emph{mail} from a @emph{iworld} and an @tech{S-expression}.}
}
]
@ -977,8 +977,7 @@ The @tech{server} itself is created with a description that includes the
@defform/subs[#:id universe
#:literals
(start stop max-worlds on-new on-msg on-tick
on-disconnect to-string)
(on-new on-msg on-tick on-disconnect to-string)
(universe state-expr clause ...)
([clause
(on-new new-expr)
@ -1012,10 +1011,10 @@ The mandatory clauses of a @scheme[universe] server description are
@item{
@defform[(on-new new-expr)
#:contracts
([new-expr (-> [listof world?] (unsyntax @tech{UniverseState}) world? bundle?)])]{
([new-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) iworld? bundle?)])]{
tell DrScheme to call the function @scheme[new-expr] every time another world joins the
universe. The event handler is called on the current list of worlds and the
joining world, which isn't on the list yet. In particular, the handler may
universe. The event handler is called on the current list of iworlds and the
joining iworld, which isn't on the list yet. In particular, the handler may
reject a @tech{world} program from participating in a @tech{universe},
simply by not including it in the resulting @scheme[bundle] structure. The
handler may still send one message to the world that attempts to join. }
@ -1024,7 +1023,7 @@ The mandatory clauses of a @scheme[universe] server description are
@item{
@defform[(on-msg msg-expr)
#:contracts
([msg-expr (-> [listof world?] (unsyntax @tech{UniverseState}) world? sexp? bundle?)])]{
([msg-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) iworld? sexp? bundle?)])]{
tell DrScheme to apply @scheme[msg-expr] to the list of currently
participating worlds @scheme[low], the current state of the universe, the world
@ -1055,7 +1054,7 @@ optional handlers:
@item{
@defform/none[(on-tick tick-expr)
#:contracts
([tick-expr (-> [listof world?] (unsyntax @tech{UniverseState}) bundle?)])]{
([tick-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) bundle?)])]{
tell DrScheme to apply @scheme[tick-expr] to the current list of
participating worlds and the current state of the
universe.
@ -1063,7 +1062,7 @@ optional handlers:
@defform/none[(on-tick tick-expr rate-expr)
#:contracts
([tick-expr (-> [listof world?] (unsyntax @tech{UniverseState}) bundle?)]
([tick-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) bundle?)]
[rate-expr natural-number/c])]{
tell DrScheme to apply @scheme[tick-expr] as above but use the specified
clock tick rate instead of the default.
@ -1074,7 +1073,7 @@ optional handlers:
@item{
@defform[(on-disconnect dis-expr)
#:contracts
([dis-expr (-> [listof world?] (unsyntax @tech{UniverseState}) world? bundle?)])]{
([dis-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) iworld? bundle?)])]{
tell DrScheme to invoke @scheme[dis-expr] every time a participating
@tech{world} drops its connection to the server. The first two arguments
are the current list of participating worlds and the state of the
@ -1085,7 +1084,7 @@ optional handlers:
@item{
@defform[(to-string render-expr)
#:contracts
([render-expr (-> [listof world?] (unsyntax @tech{UniverseState}) string?)])]{
([render-expr (-> [listof iworld?] (unsyntax @tech{UniverseState}) string?)])]{
tell DrScheme to render the state of the universe after each event and to
display this string in the universe console.
}
@ -1212,14 +1211,14 @@ translates into the design of two functions with the following headers,
#reader scribble/comment-reader
(schemeblock
;; Bundle is
;; (make-bundle [Listof world?] UniverseState [Listof mail?])
;; (make-bundle [Listof iworld?] UniverseState [Listof mail?])
;; [Listof world?] UniverseState world? -> Bundle
;; [Listof iworld?] UniverseState iworld? -> Bundle
;; compute next list of worlds and new @tech{UniverseState}
;; when world w is joining the universe, which is in state s;
(define (add-world s w) ...)
;; [Listof world?] UniverseState world? W2U -> Bundle
;; [Listof iworld?] UniverseState iworld? W2U -> Bundle
;; compute next list of worlds and new @tech{UniverseState}
;; when world w is sending message m to universe in state s
(define (process s p m) ...)
@ -1245,27 +1244,27 @@ As for the server's state, it must obviously keep track of all @tech{world}s tha
no @tech{world}s and, at that point, the server has nothing to track.
While there are many different useful ways of representing such a
@tech{universe}, we just use the list of @emph{worlds} that is handed to
@tech{universe}, we just use the list of @emph{iworlds} that is handed to
each handler and that handlers return via their bundles. The
@tech{UniverseState} itself is useless for this trivial example. We
interpret non-empty lists as those where the first @tech{world} is active
and the remainder are the passive @tech{world}s. As for the two possible
interpret non-empty lists as those where the first @emph{iworld} is active
and the remainder are the passive @emph{iworld}s. As for the two possible
events,
@itemize[
@item{it is natural to add new @tech{world}s to the end of the list; and}
@item{it is natural to add new @emph{iworld}s to the end of the list; and}
@item{it is natural to move an active @tech{world} that relinquishes its turn to
@item{it is natural to move an active @emph{iworld} that relinquishes its turn to
the end of the list, too.}
]
The server should send messages to the first @tech{world} of its list as
long as it wishes this @tech{world} to remain active. In turn, it should
expect to receive messages only from this one active @tech{world} and no
other @tech{world}. The content of these two messages is nearly irrelevant
because a message from the server to a @tech{world} means that it is the
@tech{world}'s turn and a message from the @tech{world} to the server
The server should send messages to the first @emph{iworld} of its list as
long as it wishes this @emph{iworld} to remain active. In turn, it should
expect to receive messages only from this one active @emph{iworld} and no
other @emph{iworld}. The content of these two messages is nearly irrelevant
because a message from the server to a @emph{iworld} means that it is the
@emph{iworld}'s turn and a message from the @emph{iworld} to the server
means that the turn is over. Just so that we don't confuse ourselves, we
use two distinct symbols for these two messages:
@itemize[