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add and use at-exp meta-language

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svn: r13731

original commit: 128d5287f7791c69634519438af43c0b29c35f1c
This commit is contained in:
Matthew Flatt 2009-02-18 23:14:18 +00:00
parent 00623a67ae
commit c3b18904af
1 changed files with 26 additions and 4 deletions
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30
collects/scribblings/scribble/reader.scrbl
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@ -23,13 +23,16 @@ You can use the reader via MzScheme's @schemefont{#reader} form:
#reader scribble/reader @foo{This is free-form text!} #reader scribble/reader @foo{This is free-form text!}
}|] }|]
or use the @scheme[at-exp] meta-language as described in
@secref["at-exp-lang"].
Note that the Scribble reader reads @"@"-forms as S-expressions. This Note that the Scribble reader reads @"@"-forms as S-expressions. This
means that it is up to you to give meanings for these expressions in means that it is up to you to give meanings for these expressions in
the usual way: use Scheme functions, define your functions, or require the usual way: use Scheme functions, define your functions, or require
functions. For example, typing the above into MzScheme is likely functions. For example, typing the above into MzScheme is likely
going to produce a ``reference to undefined identifier'' error --- you going to produce a ``reference to undefined identifier'' error, unless
can use @scheme[string-append] instead, or you can define @scheme[foo] @scheme[foo] is defined. You can use @scheme[string-append] instead,
as a function (with variable arity). or you can define @scheme[foo] as a function (with variable arity).
A common use of the Scribble @"@"-reader is when using Scribble as a A common use of the Scribble @"@"-reader is when using Scribble as a
documentation system for producing manuals. In this case, the manual documentation system for producing manuals. In this case, the manual
@ -37,7 +40,7 @@ text is likely to start with
@schememod[scribble/doc] @schememod[scribble/doc]
which installs the @"@" reader starting in ``text mode'', wraps the which installs the @"@" reader starting in ``text mode,'' wraps the
file content afterward into a MzScheme module where many useful Scheme file content afterward into a MzScheme module where many useful Scheme
and documentation related functions are available, and parses the body and documentation related functions are available, and parses the body
into a document using @schememodname[scribble/decode]. See into a document using @schememodname[scribble/decode]. See
@ -833,6 +836,25 @@ is an example of this.
}) })
] ]
@;--------------------------------------------------------------------
@section[#:tag "at-exp-lang"]{Adding @"@"-expressions to a Language}
@defmodulelang[at-exp]{The @schememodname[at-exp] language installs
@"@"-reader support in the readtable, and then chains to the reader of
another language that is specified immediate after
@schememodname[at-exp].}
For example, @scheme[#, @hash-lang[] at-exp scheme/base] adds @"@"-reader
support to @scheme[scheme/base], so that
@schememod[
at-exp scheme/base
(define (greet who) #, @elem{@tt["@"]@scheme[string-append]@schemeparenfont["{"]@schemevalfont{Hello, }@tt["@|"]@scheme[who]@tt["|"]@schemevalfont{.}@schemeparenfont["}"]})
(greet "friend")]
reports @scheme["Hello, friend."].
@;-------------------------------------------------------------------- @;--------------------------------------------------------------------
@section{Interface} @section{Interface}