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Document R6RS hex escapes

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* doc/ref/api-data.texi (Characters, String Syntax): document r6rs hex
  escapes

* doc/ref/api-options.texi (Reader Options): document r6rs-hex-escapes
  reader option
This commit is contained in:
Michael Gran 2010-01-13 07:26:10 -08:00
parent 898a0b5a2e
commit 6ea3048785
2 changed files with 32 additions and 2 deletions
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26
doc/ref/api-data.texi
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@ -1764,6 +1764,18 @@ Characters may also be written using their code point values. They can
be written with as an octal number, such as @code{#\10} for
@code{#\bs} or @code{#\177} for @code{#\del}.
When the @code{r6rs-hex-escapes} reader option is enabled, there is an
additional syntax for character escapes: @code{#\xHHHH} -- the letter 'x'
followed by a hexadecimal number of one to eight digits.
@lisp
(read-enable 'r6rs-hex-escapes)
@end lisp
Enabling this option will also change the hex escape format for strings. More
on string escapes can be found at (@pxref{String Syntax}). More on reader
options in general can be found at (@pxref{Reader options}).
@rnindex char?
@deffn {Scheme Procedure} char? x
@deffnx {C Function} scm_char_p (x)
@ -2675,6 +2687,20 @@ The following are examples of string literals:
"\"Hi\", he said."
@end lisp
The three escape sequences @code{\xHH}, @code{\uHHHH} and @code{\UHHHHHH} were
chosen to not break compatibility with code written for previous versions of
Guile. The R6RS specification suggests a different, incompatible syntax for hex
escapes: @code{\xHHHH;} -- a character code followed by one to eight hexadecimal
digits terminated with a semicolon. If this escape format is desired instead,
it can be enabled with the reader option @code{r6rs-hex-escapes}.
@lisp
(read-enable 'r6rs-hex-escapes)
@end lisp
Enabling this option will also change the hex escape format for characters.
More on character escapes can be found at (@pxref{Characters}). More on
reader options in general can be found at (@pxref{Reader options}).
@node String Predicates
@subsubsection String Predicates

6
doc/ref/api-options.texi
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@ -1,6 +1,6 @@
@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009
@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010
@c Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
@ -510,6 +510,7 @@ keywords #f Style of keyword recognition: #f, 'prefix or 'postfix
case-insensitive no Convert symbols to lower case.
positions yes Record positions of source code expressions.
copy no Copy source code expressions.
r6rs-hex-escapes no Use R6RS-style string and character hex escapes
@end smalllisp
Notice that while Standard Scheme is case insensitive, to ease
@ -522,6 +523,9 @@ To make Guile case insensitive, you can type
(read-enable 'case-insensitive)
@end lisp
For more information on the effect of the @code{r6rs-hex-escapes} option, see
(@pxref{Characters}) and (@pxref{String Syntax}).
@node Printing options
@subsubsection Printing options