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rackety quick doc

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Matthew Flatt 2010-04-21 19:16:01 -06:00
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@ -1,6 +1,6 @@
#lang scribble/doc
@title{@bold{Quick}: An Introduction to PLT Scheme with Pictures}
@title{@bold{Quick}: An Introduction to Racket with Pictures}
@author["Matthew Flatt"]
@ -24,22 +24,22 @@
@; ----------------------------------------------------------------------
This tutorial provides a brief introduction to the PLT Scheme
This tutorial provides a brief introduction to the Racket
programming language by using one of its picture-drawing
libraries. Even if you don't intend to use Scheme for your artistic
libraries. Even if you don't intend to use Racket for your artistic
endeavours, the picture library supports interesting and enlightening
examples. After all, a picture is worth five hundred ``hello world''s.
Along the same lines, we assume that you will run the examples using
@link[url:download-drscheme]{DrScheme}. Using DrScheme is the fastest
@link[url:download-drscheme]{DrRacket}. Using DrRacket is the fastest
way to get a sense of what the language and system feels like, even if
you eventually use Scheme with Emacs, vi, or some other editor.
you eventually use Racket with Emacs, vi, or some other editor.
@; ----------------------------------------------------------------------
@section{Ready...}
@link[url:download-drscheme]{Download PLT Scheme}, install, and then
start DrScheme.
@link[url:download-drscheme]{Download Racket}, install, and then
start DrRacket.
@; ----------------------------------------------------------------------
@section{Set...}
@ -47,22 +47,22 @@ start DrScheme.
To draw pictures, we must first load some picture functions, which are
part of a library for creating slide presentations. Copy the
following into the @defterm{definitions area}, which is the top text
area that you see in DrScheme:
area that you see in DrRacket:
@schememod[slideshow]
Then click the @onscreen{Run} button. You'll see the text caret move
to the bottom text area, which is the @defterm{interactions area}.
If you've used DrScheme before, you might need to manually reset the
language to @onscreen{Module} via the @menuitem["Language" "Choose
Language..."] menu item before clicking @onscreen{Run}.
If you've used DrRacket before, you might need to reset DrRacket to
use the language declared in the source via the @menuitem["Language"
"Choose Language..."] menu item before clicking @onscreen{Run}.
@; ----------------------------------------------------------------------
@section{Go!}
When you type an expression after the @onscreen{>} in the interactions
window and hit Enter, DrScheme evaluates the expression and prints its
window and hit Enter, DrRacket evaluates the expression and prints its
result. An expression can be just a value, such as the number
@scheme[5] or the string @scheme["art gallery"]:
@ -87,12 +87,12 @@ what happens:
@mr-interaction[(circle 10 20)]
Note that DrScheme highlights in pink the expression that triggered
Note that DrRacket highlights in pink the expression that triggered
the error (but pink highlighting is not shown in this documentation).
In addition to basic picture constructors like @scheme[circle] and
@scheme[rectangle], there's a @scheme[hc-append] function that
combines pictures. When you start composing function calls in Scheme,
combines pictures. When you start composing function calls in Racket,
it looks like this:
@mr-interaction[(hc-append (circle 10) (rectangle 10 20))]
@ -105,7 +105,7 @@ because it combines pictures horizontally, and the next letter is
If you wonder what other functions exist---perhaps a way to stack
pictures vertically and left-aligned?---move the text caret to the
name @scheme[hc-append] and press the F1 key in DrScheme. A browser
name @scheme[hc-append] and press the F1 key in DrRacket. A browser
window will open, and it will give you a link to the documentation for
@scheme[hc-append]. Click the link, and you'll see lots of other
functions.
@ -183,7 +183,7 @@ bindings. For example, it can be used inside a function body:
(four (circle 10))
]
More typically, Schemers use the @scheme[let] or @scheme[let*] form
More typically, Racketeers use the @scheme[let] or @scheme[let*] form
for local binding. An advantage of @scheme[let] is that it can be used
in any expression position. Also, it binds many identifiers at once,
instead of requiring a separate @scheme[define] for each identifier:
@ -222,7 +222,7 @@ Instead of calling @scheme[circle] as a function, try evaluating just
That is, the identifier @scheme[circle] is bound to a function
(a.k.a. ``procedure''), just like @scheme[c] is bound to a
circle. Unlike a circle picture, there's not a simple way of
completely printing the function, so DrScheme just prints
completely printing the function, so DrRacket just prints
@procedure{circle}.
This example shows that functions are values, just like numbers and
@ -249,7 +249,7 @@ anonymous function:
The parenthesized names after a @scheme[lambda] are the arguments to
the function, and the expression after the argument names is the
function body. Using the word ``lambda'' instead of ``function'' or
``procedure'' is part of Scheme's history and culture.
``procedure'' is part of Racket's history and culture.
A @scheme[define] form for a function is really a shorthand for a
simple @scheme[define] using @scheme[lambda] as the value. For
@ -261,13 +261,13 @@ example, the @scheme[series] definition could be written as
(hc-append 4 (mk 5) (mk 10) (mk 20))))
]
Most Schemers prefer to use the shorthand function form with
Most Racketeers prefer to use the shorthand function form with
@scheme[define] instead of expanding to @scheme[lambda].
@; ----------------------------------------------------------------------
@section{Lexical Scope}
Scheme is a lexically scoped language, which means that whenever an
Racket is a lexically scoped language, which means that whenever an
identifier is used as an expression, something in the textual
environment of the expression determines the identifier's
binding. This rule applies to identifiers in a @scheme[lambda] body as
@ -308,9 +308,9 @@ different alignment of objects within the picture compared to using
@; ----------------------------------------------------------------------
@section{Lists}
Scheme inherits much of its style from the language Lisp, whose name
Racket inherits much of its style from the language Lisp, whose name
originally stood for ``LISt Processor,'' and lists remain an important
part of Scheme.
part of Racket.
The @scheme[list] function takes any number of arguments and returns
a list containing the given values:
@ -326,7 +326,7 @@ here, because parentheses are used for both expressions, such as
expressions and printed results is no coincidence, but we save that
bit of culture for @seclink[#:doc '(lib
"scribblings/guide/guide.scrbl") "quoting-lists"]{discussion
elsewhere}. In the documentation and in DrScheme, result parentheses
elsewhere}. In the documentation and in DrRacket, result parentheses
are printed in blue, unlike expression parentheses.
If you have a list, then you'll eventually want to do something with
@ -386,7 +386,7 @@ Modules are named and distributed in various ways:
@itemize[
@item{Some modules are packaged in the PLT Scheme distribution or
@item{Some modules are packaged in the Racket distribution or
otherwise installed into a hierarchy of
@defterm{collections}. For example, the module name
@schememodname[slideshow/flash] means ``the module implemented
@ -404,18 +404,18 @@ Modules are named and distributed in various ways:
(random-gaussian)
]
DrScheme automatically downloads version 1.0 of the
DrRacket automatically downloads version 1.0 of the
@filepath{random.plt} library and then imports the
@filepath{random.ss} module.}
@item{Some modules live relative to other modules, without
necessarily belonging to any particular collection or package.
For example, in DrScheme, if you save your definitions so far in a
For example, in DrRacket, if you save your definitions so far in a
file @filepath{quick.ss} and add the line
@schemeblock[(provide rainbow square)]
then you can open a new tab or window in DrScheme, type the new
then you can open a new tab or window in DrRacket, type the new
program @filepath{use.ss} in the same directory as
@filepath{quick.ss}:
@ -433,7 +433,7 @@ Modules are named and distributed in various ways:
]
Schemers typically write new programs and libraries as modules that
Racketeers typically write new programs and libraries as modules that
import each other through relative paths, and that use existing
libraries from collections and @scheme[planet]. When a program or
library developed this way seems useful to others, it can be uploaded
@ -462,7 +462,7 @@ This helps explain what we meant in the previous section when we said
that @schememodname[scheme] provides @scheme[require] and the
function-calling syntax. Libraries are not restricted to exporting
values, such as functions; they can also define new syntactic
forms. In this sense, Scheme isn't exactly a language at all; it's
forms. In this sense, Racket isn't exactly a language at all; it's
more of an idea for how to structure a language so that you can extend
it or create entirely new languages.
@ -489,27 +489,27 @@ is @scheme[(hc-append 10 expr (code expr))]. In particular,
Of course, the sword of syntactic extension cuts both ways: inventing
a new language can make it easier to say what you want, but harder for
others to understand. As it happens, the developers of PLT Scheme are
constantly giving talks and writing papers that involve Scheme code,
others to understand. As it happens, the developers of Racket are
constantly giving talks and writing papers that involve Racket code,
and it's worthwhile for everyone who works on those products to know
about @scheme[code].
In fact, you might want to take a look at the @keep-file["quick.scrbl"]
@link["quick.scrbl"]{source of this document}. You'll see that it
starts with @schemefont{#lang}, but otherwise doesn't look a lot
like Scheme; nevertheless, we build this document by running its
source as a PLT Scheme program. We have to use a lot more than
@scheme[syntax-rules] to extend Scheme's syntax enough for writing
documents, but Scheme's syntactic extension can take you a long way.
like Racket; nevertheless, we build this document by running its
source as a Racket program. We have to use a lot more than
@scheme[syntax-rules] to extend Racket's syntax enough for writing
documents, but Racket's syntactic extension can take you a long way.
@; ----------------------------------------------------------------------
@section{Objects}
An object system is another example of a sophisticated language
extension that is worth learning and using for Scheme users. Objects
extension that is worth learning and using for Racket users. Objects
are sometimes better than functions, even when you have
@scheme[lambda], and objects work especially well for graphical user
interfaces. The API for Scheme's GUI and graphics system is expressed
interfaces. The API for Racket's GUI and graphics system is expressed
in terms of objects and classes.
The class system itself is implemented by the
@ -568,18 +568,18 @@ that's how a frame manages its children by default.
@; ----------------------------------------------------------------------
@section{Where to Go From Here}
This introduction to PLT Scheme purposely avoids many of the
traditional ways of introducing and distinguishing Lisp or Scheme:
This introduction to Racket purposely avoids many of the
traditional ways of introducing and distinguishing Lisp or Racket:
prefix arithmetic notation, symbols, quoting and quasiquoting lists,
@scheme[eval], first-class continuations, and the idea that all syntax
is really just a @scheme[lambda] in disguise. While those are all part
of PLT Scheme, they are not the main ingredients of day-to-day programming
in PLT Scheme.
of Racket, they are not the main ingredients of day-to-day programming
in Racket.
Instead, PLT Scheme programmers typically program with functions,
Instead, Racket programmers typically program with functions,
records, objects, exceptions, regular expressions, modules, and
threads. That is, instead of a ``minimalist'' language---which is the
way that Scheme is often described---PLT Scheme offers a rich language
way that Racket is often described---Racket offers a rich language
with an extensive set of libraries and tools.
If you are new to programming or if you have the patience to work
@ -589,10 +589,10 @@ have already read it, or if you want to see where the book will take
you, then see @other-manual['(lib
"web-server/scribblings/tutorial/continue.scrbl")].
For experienced programmers, to continue touring PLT Scheme from a
For experienced programmers, to continue touring Racket from a
systems-oriented perspective instead of pictures, your next stop is
@other-manual['(lib "scribblings/more/more.scrbl")].
To instead start learning about the full PLT Scheme language and tools
To instead start learning about the full Racket language and tools
in depth, move on to @other-manual['(lib "guide.scrbl"
"scribblings/guide")].