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Various typos, fixes PR 11189.

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This commit is contained in:
Eli Barzilay 2010-09-12 00:32:45 -04:00
parent 41812ace0f
commit 70a1733f7c
1 changed files with 31 additions and 31 deletions
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62
collects/teachpack/2htdp/scribblings/universe.scrbl
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@ -71,13 +71,13 @@ primitives.
The simplest kind of animated @tech{world} program is a time-based
simulation, which is a series of scenes. The programmer's task is to
supply a function that creates a scene for each natural number. By handing
this function to the teachpack displays the simulation.
supply a function that creates a scene for each natural number. Handing
this function to the teachpack displays the simulation.
@defproc[(animate [create-image (-> natural-number/c scene?)])
natural-number/c]{
opens a canvas and starts a clock that tick 28 times per second. Every
opens a canvas and starts a clock that ticks 28 times per second. Every
time the clock ticks, DrRacket applies @scheme[create-image] to the
number of ticks passed since this function call. The results of these
function calls are displayed in the canvas. The simulation runs until you
@ -196,7 +196,7 @@ The design of a world program demands that you come up with a data
#:contracts
([tick-expr (-> (unsyntax @tech{WorldState}) (unsyntax @tech{WorldState}))])]{
tell DrRacket to call the @scheme[tick-expr] function on the current
tells DrRacket to call the @scheme[tick-expr] function on the current
world every time the clock ticks. The result of the call becomes the
current world. The clock ticks at the rate of 28 times per second.}}
@ -206,7 +206,7 @@ current world. The clock ticks at the rate of 28 times per second.}}
#:contracts
([tick-expr (-> (unsyntax @tech{WorldState}) (unsyntax @tech{WorldState}))]
[rate-expr (and/c real? positive?)])]{
tell DrRacket to call the @scheme[tick-expr] function on the current
tells DrRacket to call the @scheme[tick-expr] function on the current
world every time the clock ticks. The result of the call becomes the
current world. The clock ticks at the rate of @scheme[rate-expr].}}
@ -228,11 +228,11 @@ For simplicity, we represent key events with strings, but not all strings
]
On rare occasions you may also encounter @scheme["\u007F"], which is the
string representing the delete key (aka rubout).
string representing the delete key (aka rubout).
Second, some keys have multiple-character string representations. Strings
with more than one character denotes arrow keys or other special events,
starting with the most important:
with more than one character denote arrow keys or other special events,
starting with the most important:
@itemize[
@item{@scheme["left"] is the left arrow;}
@item{@scheme["right"] is the right arrow;}
@ -313,7 +313,7 @@ Second, some keys have multiple-character string representations. Strings
@defform[(on-key key-expr)
#:contracts
([key-expr (-> (unsyntax @tech{WorldState}) key-event? (unsyntax @tech{WorldState}))])]{
tell DrRacket to call the @scheme[key-expr] function on the current world and a
tells DrRacket to call the @scheme[key-expr] function on the current world and a
@tech{KeyEvent} for every keystroke the user of the computer makes. The result
of the call becomes the current world.
@ -335,7 +335,7 @@ Second, some keys have multiple-character string representations. Strings
@defform[(on-release release-expr)
#:contracts
([release-expr (-> (unsyntax @tech{WorldState}) key-event? (unsyntax @tech{WorldState}))])]{
tell DrRacket to call the @scheme[release-expr] function on the current world and a
tells DrRacket to call the @scheme[release-expr] function on the current world and a
@tech{KeyEvent} for every release event on the keyboard. A release event
occurs when a user presses the key and then releases it. The second argument
indicates which key has been released. The result of the function call
@ -377,7 +377,7 @@ All @tech{MouseEvent}s are represented via strings:
(-> (unsyntax @tech{WorldState})
integer? integer? (unsyntax @tech{MouseEvent})
(unsyntax @tech{WorldState}))])]{
tell DrRacket to call @scheme[mouse-expr] on the current world, the current
tells DrRacket to call @scheme[mouse-expr] on the current world, the current
@scheme[x] and @scheme[y] coordinates of the mouse, and and a
@tech{MouseEvent} for every (noticeable) action of the mouse by the
computer user. The result of the call becomes the current world.
@ -398,7 +398,7 @@ All @tech{MouseEvent}s are represented via strings:
#:contracts
([render-expr (-> (unsyntax @tech{WorldState}) scene?)])]{
tell DrRacket to call the function @scheme[render-expr] whenever the
tells DrRacket to call the function @scheme[render-expr] whenever the
canvas must be drawn. The external canvas is usually re-drawn after DrRacket has
dealt with an event. Its size is determined by the size of the first
generated @tech{scene}.}
@ -410,7 +410,7 @@ All @tech{MouseEvent}s are represented via strings:
[width-expr natural-number/c]
[height-expr natural-number/c])]{
tell DrRacket to use a @scheme[width-expr] by @scheme[height-expr]
tells DrRacket to use a @scheme[width-expr] by @scheme[height-expr]
canvas instead of one determine by the first generated @tech{scene}.
}
@ -424,7 +424,7 @@ now.
@defform[(stop-when last-world?)
#:contracts
([last-world? (-> (unsyntax @tech{WorldState}) boolean?)])]{
tell DrRacket to call the @scheme[last-world?] function whenever the canvas is
tells DrRacket to call the @scheme[last-world?] function whenever the canvas is
drawn. If this call produces @scheme[true], the world program is shut
down. Specifically, the clock is stopped; no more
tick events, @tech{KeyEvent}s, or @tech{MouseEvent}s are forwarded to
@ -437,7 +437,7 @@ now.
#:contracts
([last-world? (-> (unsyntax @tech{WorldState}) boolean?)]
[last-picture (-> (unsyntax @tech{WorldState}) scene?)])]{
tell DrRacket to call the @scheme[last-world?] function whenever the canvas is
tells DrRacket to call the @scheme[last-world?] function whenever the canvas is
drawn. If this call produces @scheme[true], the world program is shut
down after displaying the world one last time, this time using the scene
rendered with @scheme[last-picture]. Specifically, the clock is stopped; no more
@ -462,7 +462,7 @@ and @scheme[big-bang] will close down all event handling.}
@defform[(check-with world-expr?)
#:contracts
([world-expr? (-> Any boolean?)])]{
tell DrRacket to call the @scheme[world-expr?] function on the result of
tells DrRacket to call the @scheme[world-expr?] function on the result of
every world handler call. If this call produces @scheme[true], the result
is considered a world; otherwise the world program signals an error.
}}
@ -472,7 +472,7 @@ and @scheme[big-bang] will close down all event handling.}
@defform[(record? boolean-expr)
#:contracts
([boolean-expr boolean?])]{
tell DrRacket to record all events and to enable a replay of the entire
tells DrRacket to record all events and to enable a replay of the entire
interaction. The replay action also generates one png image per scene and
an animated gif for the entire sequence.
}}
@ -482,7 +482,7 @@ and @scheme[big-bang] will close down all event handling.}
@defform[(state boolean-expr)
#:contracts
([boolean-expr boolean?])]{
tell DrRacket to display a separate window in which the current
tells DrRacket to display a separate window in which the current
state is rendered each time it is updated. This is useful for beginners
who wish to see how their world evolves---without having to design a
rendering function---plus for the debugging of world programs.
@ -543,7 +543,7 @@ Like the picture of the general workings of a @tech{world} program, this
closed (and unlocked), and open. The arrows specify how the door can go
from one state into another. For example, when the door is open, the
automatic door closer shuts the door as time passes. This transition is
indicated by the arrow labeled ``time passes.'' The other arrows represent
indicated by the arrow labeled ``time.'' The other arrows represent
transitions in a similar manner:
@itemize[
@ -772,7 +772,7 @@ The @scheme[on-receive] clause of a @scheme[big-bang] specifies the event handle
@defform[(on-receive receive-expr)
#:contracts
([receive-expr (-> (unsyntax @tech{WorldState}) sexp? (or/c (unsyntax @tech{WorldState}) package?))])]{
tell DrRacket to call @scheme[receive-expr] for every message receipt, on the current
tells DrRacket to call @scheme[receive-expr] for every message receipt, on the current
@tech{WorldState} and the received message. The result of the call becomes the current
@tech{WorldState}.
@ -798,7 +798,7 @@ When messages are sent from any of the worlds to the universe or vice versa,
there is no need for the sender and receiver to synchronize. Indeed, a sender
may dispatch as many messages as needed without regard to whether the
receiver has processed them yet. The messages simply wait in queue until
the receiving @tech{server} or @tech{world} program take care of them.
the receiving @tech{server} or @tech{world} program takes care of them.
@; -----------------------------------------------------------------------------
@section[#:tag "universe-server"]{The Universe Server}
@ -829,7 +829,7 @@ The teachpack provides a mechanism for designating event handlers for
@item{A server may play the role of a special-purpose arbiter, e.g., the referee
or administrator of a game. It may check that each world ``plays'' by the rules,
and it administrate the resources of the game.}
and it administrates the resources of the game.}
]
@ -855,7 +855,7 @@ Understanding the server's event handling functions demands several data
universe.
@defproc[(iworld? [x any/c]) boolean?]{
determines whether @scheme[x] is a @emph{iworld}. Because the universe server
determines whether @scheme[x] is an @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.}
@ -963,7 +963,7 @@ The mandatory clauses of a @scheme[universe] server description are
@defform[(on-new new-expr)
#:contracts
([new-expr (-> (unsyntax @tech{UniverseState}) iworld? bundle?)])]{
tell DrRacket to call the function @scheme[new-expr] every time another world joins the
tells DrRacket to call the function @scheme[new-expr] every time another world joins the
universe. The event handler is called with the current state 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},
@ -974,7 +974,7 @@ The mandatory clauses of a @scheme[universe] server description are
@defform[(on-msg msg-expr)
#:contracts
([msg-expr (-> (unsyntax @tech{UniverseState}) iworld? sexp? bundle?)])]{
tell DrRacket to apply @scheme[msg-expr] to the current state of the
tells DrRacket to apply @scheme[msg-expr] to the current state of the
universe, the world
@scheme[w] that sent the message, and the message itself.
}
@ -1003,14 +1003,14 @@ optional handlers:
(on-tick tick-expr)
#:contracts
([tick-expr (-> (unsyntax @tech{UniverseState}) bundle?)])]{
tell DrRacket to apply @scheme[tick-expr] to the current state of the universe.}
tells DrRacket to apply @scheme[tick-expr] to the current state of the universe.}
@defform/none[#:literals (on-tick)
(on-tick tick-expr rate-expr)
#:contracts
([tick-expr (-> (unsyntax @tech{UniverseState}) bundle?)]
[rate-expr (and/c real? positive?)])]{
tell DrRacket to apply @scheme[tick-expr] as above but use the specified
tells DrRacket to apply @scheme[tick-expr] as above but use the specified
clock tick rate instead of the default.}
}
@ -1018,7 +1018,7 @@ optional handlers:
@defform[(on-disconnect dis-expr)
#:contracts
([dis-expr (-> (unsyntax @tech{UniverseState}) iworld? bundle?)])]{
tell DrRacket to invoke @scheme[dis-expr] every time a participating
tells DrRacket to invoke @scheme[dis-expr] every time a participating
@tech{world} drops its connection to the server. The first argument
is the current state of the universe server, while the second argument is
the (representation of the) world that got disconnected. The resulting
@ -1030,7 +1030,7 @@ optional handlers:
@defform[(to-string render-expr)
#:contracts
([render-expr (-> (unsyntax @tech{UniverseState}) string?)])]{
tell DrRacket to render the state of the universe after each event and to
tells DrRacket to render the state of the universe after each event and to
display this string in the universe console.
}
}
@ -1048,7 +1048,7 @@ optional handlers:
@defform/none[(state boolean-expr)
#:contracts
([boolean-expr boolean?])]{
tell DrRacket to display a separate window in which the current
tells DrRacket to display a separate window in which the current
state is rendered each time it is updated. This is mostly useful for
debugging server programs.
}}
@ -1265,7 +1265,7 @@ 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
because a message from the server to an @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: