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much revised code, matching doc.txt and tests

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svn: r6830

original commit: 11feb6010e5a5ef159d767292f8f2851c0308729
This commit is contained in:
Eli Barzilay 2007-07-07 06:27:23 +00:00
parent edb25384b7
commit 04836721c3
1 changed files with 455 additions and 260 deletions
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collects/scribble/doc.txt
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@ -1,32 +1,4 @@
The _Scribble_ Collection
=========================
The Scribble collection contains a few libraries that can be used to
create documents from Scheme. It is made of independently usable
parts. For example, the reader can be used in any situation that
requires lots of free-form text, or you can use the rendering portion
directly to generate documents.
Running Scribble
----------------
To process a Scribble document, use the `scribble' command-line utility
(use `scribble -h' to see usage information). This is implemented by
the "run-scribble.ss" module, which can be used directly:
> (render-file input output format)
Renders the given `input' file to the `output' file using the given
format specification. The input and output files are used as is (no
suffixes are added). The `output' argument can be #f, which will render
the input to the current output port. `format' is a symbol that
specifies the kind of output rendering (use the `scribble' commad to
find the list of available formatters).
A Scribble document is a MzScheme module file, which provides a
`content' binding.
(The rest of the Scribble documentation is now a separate manual.)
The Scribble Reader
-------------------
@ -71,12 +43,16 @@ Informally, the concrete syntax of @-forms is:
where all three parts after "@" are optional, but at least one should
be present. (Note that spaces are not allowed between the three
parts.) @litchar["@"] is set as a non-terminating reader macro, so it
can be used as usual in Scheme identifiers unless you want to use it
as a first character of an identifier; in this case you need to quote
with a backslash (`\@foo@') or quote the whole identifier with bars
(`|@foo|'). Of course, "@" is not treated specially in Scheme
strings, character constants, etc.
parts.) "@" is set as a non-terminating reader macro, so it can be
used as usual in Scheme identifiers unless you want to use it as a
first character of an identifier; in this case you need to quote with
a backslash (`\@foo@') or quote the whole identifier with bars
(`|@foo|').
(define |@foo| '\@bar@baz)
Of course, "@" is not treated specially in Scheme strings, character
constants, etc.
Roughly, a form matching the above grammar is read as
@ -87,322 +63,541 @@ input. Thus, the initial <cmd> determines the Scheme code that the
input is translated into. The common case is when <cmd> is a Scheme
identifier, which generates a plain Scheme form.
A <text-body> is made of character sequences, newlines, and nested
@-forms. Note that the syntax for @-forms is the same in a
<text-body> context as in a Scheme context. A <text-body> that isn't
an @-form is converted to a string expression for its <parsed-body>,
and newlines are converted to "\n" expressions:
A <text-body> is made of text, newlines, and nested @-forms. Note
that the syntax for @-forms is the same in a <text-body> context as in
a Scheme context. A <text-body> that isn't an @-form is converted to
a string expression for its <parsed-body>, and newlines are converted
to "\n" expressions:
@foo{bar baz
blah}
--is-read-as-->
--reads-as-->
(foo "bar baz" "\n" "blah")
@foo{bar @baz[3]
blah}
--is-read-as-->
(foo (baz 3) "\n" "blah")
--reads-as-->
(foo "bar " (baz 3) "\n" "blah")
@foo{bar @baz{3}
blah}
--is-read-as-->
--reads-as-->
(foo "bar " (baz "3") "\n" "blah")
@foo{bar @baz[2 3]{4 5}
blah}
--is-read-as-->
--reads-as-->
(foo "bar " (baz 2 3 "4 5") "\n" "blah")
Note that spaces are not allowed before a "[" or a "{", or they will
be part of the following text (or Scheme code). (More on using braces
in body texts below.)
@foo{bar @baz[2 3] {4 5}}
--reads-as-->
(foo "bar " (baz 2 3) " {4 5}")
When the above @-forms appear in a Scheme expression context, the
context must provide bindings for `foo' (as a procedure or macro). To
just see the read result for an @-form, you can always a Scheme
`quote':
lexical environment must provide bindings for `foo' (as a procedure or
a macro).
(let* ([formatter (lambda (fmt)
(lambda args (format fmt (apply string-append args))))]
[bf (formatter "*~a*")]
[it (formatter "/~a/")]
[ul (formatter "_~a_")]
[text string-append])
@text{@it{Note}: @bf{This is @ul{not} a pipe}.})
--> "/Note/: *This is _not_ a pipe*."
If you want to see the expression that is actually being read, you can
use Scheme's `quote'.
'@foo{bar}
** Concrete Syntax: The Command Part
Besides being a Scheme identifier, the <cmd> part of an @-form can be
any Scheme expression. The expression can have Scheme punctuation
prefixes, which will end up wrapping the *whole* expression.
Besides being a Scheme identifier, the <cmd> part of an @-form can
have Scheme punctuation prefixes, which will end up wrapping the
*whole* expression.
@`',@foo{blah}
--is-read-as-->
`',@(foo "blah")
@`',@foo{blah} --reads-as--> `',@(foo "blah")
When writing Scheme code, this means that @`',@foo{blah} is exactly
the same as `@',@foo{blah} and `',@@foo{blah}, but unlike the latter
two, the first construct can appear in body texts with the same
meaning, whereas the other two would not work (see below).
As mentioned above, the command itself is not limited to a Scheme
identifier; it can be any Scheme expression.
@(lambda (x) x){blah}
--is-read-as-->
((lambda (x) x) "blah")
After the optional punctuation prefix, the <cmd> itself is not limited
to identifiers -- it can be *any* Scheme expression.
@(lambda (x) x){blah} --reads-as--> ((lambda (x) x) "blah")
@`(unquote foo){blah} --reads-as--> `(,foo "blah")
In addition, the command can be omitted altogether, which will omit it
from the translation, resulting in an s-expression that usually contains
just strings:
from the translation, resulting in an S-expression that usually
contains, say, just strings:
@{foo bar --is-read-as--> ("foo bar" "\n" "baz")
@{foo bar --reads-as--> ("foo bar" "\n" "baz")
baz}
@'{foo bar --is-read-as--> '("foo bar" "\n" "baz")
@'{foo bar --reads-as--> '("foo bar" "\n" "baz")
baz}
If the command part begins with a ";" (with no newline between the "@"
and the ";"), then the construct is a comment. There are two comment
forms, one for arbitrary-text and possibly nested comments, and another
one for a -to-the-end-of-the-line comment:
forms, one for arbitrary-text and possibly nested comments, and
another one for a line comments:
@;{ ...any-text-including-tested-scribble-pieces... }
@;{<anything> ...}
@; <anything-that-doesn't-begin-with-a-brace-to-the-end-of-the-line>
@;<anything-else-without-newline>
Note that the first form is analogous to a "#;" comment: the commented
body must still parse correctly. Also note that in the second form all
text from the "@;" to the end of the line and all following
(non-newline) whitespaces are part of the comment (as with TeX `%'
comments). For example:
In the first form, the commented body must still parse correctly; see
the description of the body syntax below. In the second form, all
text from the "@;" to the end of the line *and* all following spaces
(or tabs) are part of the comment (similar to "%" comments in TeX).
@foo{bar @; comment --is-read-as--> (foo "bar baz")
@foo{bar @; comment --reads-as--> (foo "bar baz")
baz}
Tip: if you're editing in a Scheme-aware editor, it is useful to comment
out blocks like this:
@;
{
...
}
or
Tip: if you're editing in a Scheme-aware editor (like DrScheme or
Emacs), it is useful to comment out blocks like this:
@;{
...
;}
otherwise you will probably confuse the editor into treating the file as
having imbalanced parenthesis.
so the editor does not treat the file as having unbalanced
parenthesis.
If only the command part is specified, then the result is the command
part only, without an extra set of parenthesis. This makes it suitable
for Scheme escapes in body texts. More below, in the description of the
body part.
If only the <cmd> part of an @-form is specified, then the result is
the command part only, without an extra set of parenthesis. This
makes it suitable for Scheme escapes in body texts. (More on this
below, in the description of the body part.)
Finally, note that there are no special rules for using "@" in the
command itself, which can lead to things like:
@foo{x @y z} --reads-as--> (foo "x " y " z")
@foo{x @(* y 2) z} --reads-as--> (foo "x " (* y 2) " z")
@{@foo bar} --reads-as--> (foo " bar")
@@foo{bar}{baz} --is-read-as--> ((foo "bar") "baz")
Finally, note that there are currently no special rules for using "@"
in the command itself, which can lead to things like:
To use "@" as in plain Scheme code, you need to quote it as you would
quote other characters, for example:
@@foo{bar}{baz} --reads-as--> ((foo "bar") "baz")
(define |@foo| '\@bar)
** Concrete Syntax: The Datum Part
** Concrete Syntax: the body part
The datum part can contains arbitrary Scheme expressions, which are
simply stacked before the body text arguments:
The syntax of the body part is intended to be as convenient as possible
for writing free text. It can contain almost any text -- the only
character with special meaning is "@", in addition, braces, "|", and
backslash can have special meanings but only in a few contexts. As
described above, the text turns to a sequence of string arguments for
the resulting form. Spaces at the beginning of lines are discarded (but
see the information about indentation below), and newlines turn to
individual "\n" strings. (Spaces are preserved on a single-line text.)
As part of trying to do the `right thing', an empty line at the
beginning and at the end are discarded, so
@foo[1 (* 2 3)]{bar} --reads-as--> (foo 1 (* 2 3) "bar")
@foo[@bar{...}]{blah} --reads-as--> (foo (bar "...") "blah")
The body part can still be omitted, which is essentially an
alternative syntax for plain (non-textual) S-expressions:
@foo[bar] --reads-as--> (foo bar)
@foo{bar @f[x] baz} --reads-as--> (foo "bar " (f x) " baz")
The datum part can be empty, which makes no difference, except when
the body is omitted. It is more common, however, to use an empty body
for the same purpose.
@foo[]{bar} --reads-as--> (foo "bar")
@foo[] --reads-as--> (foo)
@foo --reads-as--> foo
@foo{} --reads-as--> (foo)
The most common use of the datum part is for Scheme forms that expect
keyword-value arguments that precede the body of text arguments.
@foo[#:style 'big]{bar} --reads-as--> (foo #:style 'big "bar")
** Concrete Syntax: The Body Part
The syntax of the body part is intended to be as convenient as
possible for free text. It can contain almost any text -- the only
characters with special meaning is "@" for sub forms, and "}" for the
end of the text. In addition, a "{" is allowed as part of the text,
and it makes the matching "}" be part of the text too -- so balanced
braces are valid text.
@foo{f{o}o} --reads-as--> (foo "f{o}o")
@foo{{{}}{}} --reads-as--> (foo "{{}}{}")
As described above, the text turns to a sequence of string arguments
for the resulting form. Spaces at the beginning and end of lines are
discarded, and newlines turn to individual "\n" strings (i.e., they
are not merged with other body parts). (See also the information
about newlines and indentation below.) Spaces are *not* discarded if
they appear after the open "{" (before the closing "}") when there is
also text that follows (precedes) it; specifically, they are preserved
in a single-line body.
@foo{bar} --reads-as--> (foo "bar")
@foo{ bar } --reads-as--> (foo " bar ")
@foo[1]{ bar } --reads-as--> (foo 1 " bar ")
If "@" appears in a body, then it is interpreted as Scheme code, which
means that the @-reader is applied recursively, and the resulting
syntax appears as part of the S-expression, among other string
contents.
@foo{a @bar{b} c} --reads-as--> (foo "a " (bar "b") " c")
If the nested "@" construct has only a command -- no body or datum
parts -- it will not appear in a subform. Given that the command part
can be any Scheme expression, this makes "@" a general escape to
arbitrary Scheme code.
@foo{a @bar c} --reads-as--> (foo "a " bar " c")
@foo{a @(bar 2) c} --reads-as--> (foo "a " (bar 2) " c")
This is particularly useful with strings, which can be used to include
arbitrary text.
@foo{This @"}" is a closing brace}
--reads-as-->
(foo "This } is a closing brace")
Note that the escaped string is (intentionally) merged with the rest
of the text. This works for "@" too:
@foo{The command prefix is @"@".}
--reads-as-->
(foo "The command prefix is @.")
@foo{@"@foo{bar}" reads as (foo "bar")}
--reads-as-->
(foo "@foo{bar} reads as (foo \"bar\")")
* Concrete Syntax: Alternative Body Syntax
In addition, there is an alternative syntax for the body, one that
specifies a new marker for its end: use "|{" for the opening marker to
have the text terminated by a "}|".
@foo|{...}|
--reads-as-->
(foo "...")
@foo|{close with "}", open with "{"}|
--reads-as-->
(foo "close with \"}\", open with \"{\"")
@foo|{Nesting |{is}| ok}|
--reads-as-->
(foo "Nesting |{is}| ok")
This applies to sub-@-forms too -- the "@" must be prefixed with a
"|":
@foo|{Maze
|@bar{is}
Life!}|
--reads-as-->
(foo "Maze" "\n" (bar "is") "Life!")
@foo|{Works for |@bar|{subforms}| too}|
--reads-as-->
(foo "Works for " (bar "subforms") " too")
Note that the subform uses its own delimiters, "{...}" or "|{...}|".
This means that you can copy and paste Scribble text with @-forms
freely, just prefix the "@" if the immediate surrounding text has a
prefix.
For even better control, you can add characters in the opening
delimiter, between the "|" and the "{". Characters that are put there
(non alphanumeric ASCII characters only, excluding "{" and "@") should
also be used for sub-@-forms, and the end-of-body marker should have
these characters in reverse order with paren-like characters ("(",
"[", "<") mirrored.
@foo|<<<{Some @x{more} |@{text}|.}>>>|
--reads-as-->
(foo "Some @x{more} |@{text}|.")
@foo|!!{Blah |!!@bold{blah}...}!!|
--reads-as-->
(foo "Blah " (bold "blah") "...")
Finally, remember that you can use an expression escape with a Scheme
string for confusing situations. This works well when you only need
to quote short pieces, and the above works well when you have larger
multi-line body texts.
* Concrete Syntax: Scheme Expression Escapes
In some cases, you may want to use a Scheme identifier (or a number or
a boolean etc.) in a position that touches the following text; in
these situations you should surround the escaped Scheme expression by
a pair of "|" characters. The text inside the bars is parsed as a
Scheme expression.
@foo{foo@bar.} --reads-as--> (foo "foo" bar.)
@foo{foo@|bar|.} --reads-as--> (foo "foo" bar ".")
@foo{foo@3.} --reads-as--> (foo "foo" 3.0)
@foo{foo@|3|.} --reads-as--> (foo "foo" 3 ".")
This form is a generic Scheme expression escape, there is no body text
or datum part when you use this form.
@foo{foo@|(f 1)|{bar}} --reads-as--> (foo "foo" (f 1) "{bar}")
@foo{foo@|bar|[1]{baz}} --reads-as--> (foo "foo" bar "[1]{baz}")
This works for string expressions too, but not that unlike the above,
the string is (intentionally) not merged with the rest of the text:
@foo{x@"y"z} --reads-as--> (foo "xyz")
@foo{x@|"y"|z} --reads-as--> (foo "x" "y" "z")
Expression escapes also work with *any* number of expressions,
@foo{x@|1 (+ 2 3) 4|y} --reads-as--> (foo "x" 1 (+ 2 3) 4 "y")
@foo{x@|* --reads-as--> (foo "x" * * "y")
*|y}
It seems that "@||" has no purpose -- but remember that these escapes
are never merged with the surrounding text, which can be useful when
you want to control the sub expressions in the form.
@foo{Alice@||Bob@| --reads-as--> (foo "Alice" "Bob" "Carol")
|Carol}
Note that "@|{...}|" can be parsed as either an escape expression or
as a no-command @-form. The latter is used in this case (since there
is little point in Scheme code that uses braces.
@|{blah}| --is-read-as--> ("blah")
* Concrete Syntax: Comments
As noted above, there are two kinds of Scribble comments: "@;{...}" is
a (nestable) comment for a whole body of text (following the same
rules for @-forms), and "@;..." is a line-comment.
@foo{First line@;{there is still a
newline at this point;}
Second line}
--reads-as-->
(foo "First line" "\n" "Second line")
One useful property of line-comments is that they continue to the end
of the line *and* all following spaces (or tabs). Using this, you can
get further control of the subforms.
@foo{This is @;
a pretty long @;
single string-@;
argument.}
--reads-as-->
(foo "This is a pretty long single string-argument.")
Note how this is different from using "@||"s in that strings around it
are not merged.
* Concrete Syntax: Spaces, Newlines, and Indentation
The Scribble syntax treats spaces and newlines in a special way is
meant to be sensible for dealing with text. As mentioned above,
spaces at the beginning and end of body lines are discarded, except
for spaces between a "{" and text, or between text and a "}".
@foo{bar} --reads-as--> (foo "bar")
@foo{ bar } --reads-as--> (foo " bar ")
@foo{ bar --reads-as--> (foo " bar" "\n" "baz ")
baz }
A single newline that follows an open brace or precedes a closing brace is
discarded, unless there are only newlines in the body; other newlines
are read as a "\n" string
@foo{bar --reads-as--> (foo "bar")
}
@foo{
bar --is-read-as--> (foo "bar") <--is-read-as-- @foo{bar}
bar --reads-as--> (foo "bar")
}
@foo{ bar } --is-read-as--> (foo " bar ")
@foo{
If an "@" appears in the input, then it is interpreted as Scheme code,
which means that the at-reader will be applied recursively, and the
resulting syntax will appear as an argument, among other string
contents. For example:
bar --reads-as--> (foo "\n" "bar" "\n")
@foo{a @bar{b} c} --is-read-as--> (foo "a " (bar "b") " c")
}
If the nested "@" construct has only a command -- no body part, then it
does not appear in a subform. Given that the command part can be any
Scheme expression, this makes "@" a general escape to arbitrary Scheme
code:
@foo{
bar
--reads-as--> (foo "bar" "\n" "\n" "baz")
baz
}
@foo{a @bar c} --is-read-as--> (foo "a " bar " c")
@foo{ --reads-as--> (foo "\n")
}
@foo{a @(bar 2) c} --is-read-as--> (foo "a " (bar 2) " c")
@foo{
--reads-as--> (foo "\n" "\n")
}
In some cases, you may want to use a Scheme identifier (or a number or a
boolean) in a position that touches other text that can make an
identifier -- in these situations you should surround the Scheme
identifier (/number/boolean) by a pair of bar characters. The text
inside the bars is parsed as a Scheme expression, but if that fails, it
is used as a quoted identifier -- do not rely on this behavior, and
avoid using whitespace inside the bars. Also, if bars are used, then no
body text is used even if they are followed by braces (see the next
paragraph). Examples:
@foo{ bar --reads-as--> (foo " bar" "\n" "baz ")
baz }
@foo{foo @bar foo} --is-read-as--> (foo "foo " bar " foo")
In the parsed S-expression syntax, a single newline string is used for
all newlines; you can use `eq?' to identify this line. This can be
used to identify newlines in the original <text-body>.
@foo{foo@bar.} --is-read-as--> (foo "foo" bar.)
(let ([nl (car @'{
})])
(for-each (lambda (x) (display (if (eq? x nl) "\n... " x)))
@`{foo
@,@(list "bar" "\n" "baz")
blah})
(newline))
--prints-->
foo
... bar
baz
... blah
@foo{foo@|bar|.} --is-read-as--> (foo "foo" bar ".")
Spaces at the beginning of body lines do not appear in the resulting
S-expressions, but the column of each line is noticed, and all-space
indentation strings are added so the result has the same indentation.
A indentation string is added to each line according to its distance
from the leftmost syntax object (except for empty lines). (Note: if
you try these examples on a mzscheme REPL, you should be aware that
the reader does not know about the "> " prompt.)
@foo{foo@3.} --is-read-as--> (foo "foo" 3.0)
@foo{ --reads-as--> (foo "bar" "\n"
bar "baz" "\n"
baz "blah")
blah
}
@foo{foo@|3|.} --is-read-as--> (foo "foo" 3 ".")
@foo{ --reads-as--> (foo "begin" "\n"
begin " " "x++;" "\n"
x++; "end")
end}
@foo{foo@|(f 1)|{bar}.} --is-read-as--> (foo "foo" (f 1) "{bar}.")
@foo{ --reads-as--> (foo " " "a" "\n"
a " " "b" "\n"
b "c")
c}
Braces are only problematic because a "}" is used to mark the end of the
text. They are therefore allowed, as long as they are balanced. For
example:
If the first string came from the openning "{" line, it is not
prepended with an indentation (but it can affect the leftmost syntax
object used for indentation). This makes sense when formatting
structured code as well as text (see the last example in the following
block).
@foo{f{o}o} --is-read-as--> (foo "f{o}o")
There is also an alternative syntax for the body, one that specifies a
new marker for the end. To do this, use "|{" for the openning marker,
optionally with additional characters between them (excluding "{",
whitespace, and alphanumerics) -- the matching closing marker should be
the mirrored form of the openning marker (reverse the characters and
swap round, square, curly, and angle parentheses). For example:
@foo|{...}| --is-read-as--> (foo "...")
@foo|{foo{{{bar}| --is-read-as--> (foo "foo{{{bar")
@foo|<{{foo{{{bar}}>| --is-read-as--> (foo "{foo{{{bar}")
* Concrete Syntax: quoting in body texts
To quote braces or "@", precede them with a backslash. Note that this
is an irregular use of backslash quoting! To use "\@" in your text,
simply precede it with a backslash. The general rule is that to use N
backslashes-and-a-special-character, you should precede it with one
extra backslash. Any other use of a backslash (one that is not followed
by more back-slashes and a special character) is preserved in the text
as usual. Examples:
@foo{b\@ar} --is-read-as--> (foo "b@ar")
@foo{b\\@ar} --is-read-as--> (foo "b\\@ar")
@foo{b\\\@ar} --is-read-as--> (foo "b\\\\@ar")
@foo{b\{\@\@ar} --is-read-as--> (foo "b{@@ar")
@foo{b\ar} --is-read-as--> (foo "b\\ar")
@foo{b\\ar} --is-read-as--> (foo "b\\\\ar")
* Concrete Syntax: newlines and indentation
When indentation is used, all-space indentation string syntaxes are
perpended to the beginning of each line. The rule for adding these
string is:
- A spaces-string is added to each line according to its distance from
the leftmost syntax object;
- The first string is not prepended with indentation if it appears on
the first line of output.
Examples:
@foo{ --is-read-as--> (foo "bar" "\n"
bar " " "baz" "\n"
baz "bbb")
bbb}
@foo{bar --is-read-as--> (foo "bar" "\n"
@foo{bar --reads-as--> (foo "bar" "\n"
baz " " "baz" "\n"
bbb} "bbb")
@foo{ bar --is-read-as--> (foo " bar" "\n"
@foo{ bar --reads-as--> (foo " bar" "\n"
baz " " "baz" "\n"
bbb} " " "bbb")
@foo{bar --is-read-as--> (foo "bar" "\n"
@foo{bar --reads-as--> (foo "bar" "\n"
baz "baz" "\n"
bbb} "bbb")
@foo{ bar --is-read-as--> (foo " bar" "\n"
@foo{ bar --reads-as--> (foo " bar" "\n"
baz "baz" "\n"
bbb} "bbb")
@foo{ bar --is-read-as--> (foo " bar" "\n"
@foo{ bar --reads-as--> (foo " bar" "\n"
baz "baz" "\n"
bbb} " " "bbb")
Additional notes:
- You can identify indentation strings at the syntax level by the fact
that they have the same location information as the following syntax
object;
- This mechanism depends on line and column number information
(`use-at-readtable' turns them on for the current input port);
- To use this mechanism with nested commands that should preserve
indentation, you will need to do some additional work since the nested
use will have only its own indentation;
- When using it on a command-line, you note that the reader is not aware
of the "> " prompt, which might lead to confusing results.
@text{Some text@footnote{And a
footnote comment.}. More text.}
--reads-as-->
(text "Some text"
(footnote "And a" "\n" "footnote comment.")
". More text.")
[The following is likely to change.]
For situations where spaces at the beginning of lines matter (various
verbatim environments), you should begin a line with a "|". It has no
other special meaning -- so to use a "|" as the first character in the
text, simply use another before it.
Note that each @-form is parsed to an S-expression that has its own
indentation. This means that Scribble source can be indented like
code, but if indentation matters then you may need to apply
indentation of the outer item to all lines of the inner one. For
example, in
@code{
|(define (foo x) --is-read-as--> (code "(define (foo x)" "\n"
| |error|) " |error|)")
begin
i = 1, r = 1
@bold{while i < n do
r *= i++
done}
end
}
--reads-as-->
(code "begin" "\n"
" " "i = 1, r = 1" "\n"
" " (bold "while i < n do" "\n"
" " "r *= i++" "\n"
"done") "\n"
"end")
In other situations, newlines matter -- you might want to avoid a
newline token in some place. To avoid a newline and still break the
source line, use a line comment. As in TeX, these will consume text
up-to and including the end of the line and all following whitespace.
Example:
a formatter will need to apply the 2-space indentation to the
rendering of the `bold' body.
@foo{bar @;
baz@; --is-read-as--> (foo "bar baz.")
.}
Note that to get a first-line text to be counted as a leftmost line,
line and column accounting should be on for the input port
(`use-at-readtable' turns them on for the current input port).
Without this,
A "|" that follows this is still used for marking the beginning of the
text:
@foo{x1
x2
x3}
@foo{bar @;
baz@; --is-read-as--> (foo "bar baz .")
| .}
will not have 2-space indentations in the parsed S-expression if
source accounting is not on, but
** Concrete Syntax: the keyword-value part
@foo{x1
x2
x3}
The keyword-value part can contain arbitrary Scheme expressions, which
are simply stacked before the body text arguments:
will (due to the last line).
@foo[1 (* 2 3)]{bar} --is-read-as--> (foo 1 (* 2 3) "bar")
@foo[@bar{...}]{blah} --is-read-as--> (foo (bar "...") "blah")
For rare situations where spaces at the beginning (or end) of lines
matter, you can begin (or end) a line with a "@||".
But there is one change that makes it easy to use for keyword/values:
(a) "=" is a terminating character in the textual scope, (b) if there is
a "<identifier>=<expr>" sequence (spaces optional), then it is converted
to "#:identifier <expr>":
@foo{
@|| bar @|| --reads-as--> (foo " bar " "\n" " baz")
@|| baz}
@foo[(* 2 3) a=b]{bar} --is-read-as--> (foo (* 2 3) #:a b "bar")
Finally, you might be need a verbatim-like environment, where the
parsed body matches exactly the textual source. To make this
possible, the @-parser uses syntax properties on the resulting syntax
values. All items that are not physically in the Scribble source --
newlines and indentation-spaces -- have a 'scribble property. An
indentation string will have 'indentation as the value of this
property, and a newline will have a '(newline S) value where S is the
original newline string including spaces that precede and follow it
(which includes the indentation for the following item). To implement
a verbatim environment you need to drop indentation strings, and use
the original newline strings instead of the single-newline string.
Here is an example of this.
*** How should this be used?
This facility can be used in any way you want. All you need is to use
function names that you bind. You can even use quasi-quotes, skipping
the need for functions, for example:
> (define (important . text) @`b{@u{@big{@,@text}}})
> (important @`p{This is an important announcement!
Read it!})
(b (u (big (p "This is an important announcement!" "\n" "Read it!"))))
(define-syntax (verb stx)
(syntax-case stx ()
[(_ cmd item ...)
#`(cmd .
#,(let loop ([items (syntax->list #'(item ...))])
(if (null? items)
'()
(let* ([fst (car items)]
[prop (syntax-property fst 'scribble)]
[rst (loop (cdr items))])
(cond [(not prop) (cons fst rst)]
[(eq? prop 'indentation) rst]
[else (cons (datum->syntax-object
fst (cadr prop) fst)
rst)])))))]))
@verb[string-append]{
foo
bar
}