Vicare Scheme: scheme lex syntax characters

Characters are represented using the notation #\<character> or #\<character name> or #\x<hex scalar value>.

#\a             lower case letter a
#\A             upper case letter A
#\(             left parenthesis
#\              space character
#\nul           U+0000
#\alarm         U+0007
#\backspace     U+0008
#\tab           U+0009
#\linefeed      U+000A
#\newline       U+000A
#\vtab          U+000B
#\page          U+000C
#\return        U+000D
#\esc           U+001B
#\space         U+0020 preferred way to write a space
#\delete        U+007F
#\xFF           U+00FF
#\x03BB         U+03BB
#\x00006587     U+6587
#\x0001z        &lexical exception
#\alarmx        &lexical exception
#\alarm x       U+0007 followed by x
#\Alarm         &lexical exception
#\alert         &lexical exception
#\xA            U+000A
#\xFF           U+00FF
#\xff           U+00FF
#\x ff          U+0078 followed by another datum, ff
#\x(ff)         U+0078 followed by another datum, a parenthesized ff
#\(x)           &lexical exception
#\(x            &lexical exception
#\((x)          U+0028 followed by another datum, parenthesized x
#\x00110000     &lexical exception out of range
#\x000000001    U+0001
#\xD800         &lexical exception in excluded range

(The notation &lexical means that the line in question is a lexical syntax violation.)

Case is significant in #\<character>, and in

#\<character
name>

, but not in the <hex scalar value> of

#\x<hex scalar
value>

. A ?character must be followed by a ?delimiter or by the end of the input. This rule resolves various ambiguous cases involving named characters, requiring, for example, the sequence of characters #\space to be interpreted as the space character rather than as the character #\s followed by the identifier pace.

3.4.3.6 Characters