@iftex
@finalout
@end iftex
-@comment $Id: scheme.texinfo,v 1.96 2001/11/14 05:53:37 cph Exp $
+@comment $Id: scheme.texinfo,v 1.97 2001/11/16 20:04:02 cph Exp $
@comment %**start of header (This is for running Texinfo on a region.)
@setfilename scheme.info
@settitle MIT Scheme Reference
@titlepage
@title{MIT Scheme Reference Manual}
-@subtitle Edition 1.94
-@subtitle for Scheme Release 7.5
-@subtitle 16 July 2001
+@subtitle Edition 1.95
+@subtitle for Scheme Release 7.6.0
+@subtitle 16 November 2001
@author by Chris Hanson
@author the MIT Scheme Team
@author and a cast of thousands
* Comparison of Characters::
* Miscellaneous Character Operations::
* Internal Representation of Characters::
-* ASCII Characters::
+* ISO-8859-1 Characters::
* Character Sets::
Strings
When compiled, they do not check the types of their arguments.
@end deffn
+@deffn {procedure+} flo:finite? flonum
+@vindex +inf
+@vindex -inf
+@vindex NaN
+@cindex positive infinity (@code{+inf})
+@cindex negative infinity (@code{-inf})
+@cindex not a number (@code{NaN})
+The @acronym{IEEE} floating-point number specification supports three
+special ``numbers'': positive infinity (@code{+inf}), negative infinity
+(@code{-inf}), and not-a-number (@code{NaN}). This predicate returns
+@code{#f} if @var{flonum} is one of these objects, and @code{#t} if it
+is any other floating-point number.
+@end deffn
+
@deffn {procedure+} flo:negate flonum
This procedure returns the negation of its argument. When compiled, it
does not check the type of its argument. Equivalent to @code{(flo:- 0.
@cindex character (defn)
Characters are objects that represent printed characters, such as
letters and digits.@footnote{Some of the details in this section depend
-on the fact that the underlying operating system uses the @acronym{ASCII}
-character set. This may change when someone ports MIT Scheme to a
-non-@acronym{ASCII} operating system.}
+on the fact that the underlying operating system uses the
+@acronym{ASCII} character set. This may change when someone ports MIT
+Scheme to a non-@acronym{ASCII} operating system.}
@menu
* External Representation of Characters::
* Comparison of Characters::
* Miscellaneous Character Operations::
* Internal Representation of Characters::
-* ASCII Characters::
+* ISO-8859-1 Characters::
* Character Sets::
@end menu
A character name may include one or more @dfn{bucky bit} prefixes to
indicate that the character includes one or more of the keyboard shift
keys Control, Meta, Super, Hyper, or Top (note that the Control bucky
-bit prefix is not the same as the @acronym{ASCII} control key). The bucky
-bit prefixes and their meanings are as follows (case is not
+bit prefix is not the same as the @acronym{ASCII} control key). The
+bucky bit prefixes and their meanings are as follows (case is not
significant):
@example
@cindex character, standard
@findex char-standard?
In addition, MIT Scheme orders those characters that satisfy
-@code{char-standard?} the same way that @acronym{ASCII} does. Specifically,
-all the digits precede all the uppercase letters, and all the upper-case
-letters precede all the lowercase letters.
+@code{char-standard?} the same way that @acronym{ISO-8859-1} does.
Characters are ordered by first comparing their bucky bits part and then
their code part. In particular, characters without bucky bits come
@end example
@end deffn
-@node Internal Representation of Characters, ASCII Characters, Miscellaneous Character Operations, Characters
+@node Internal Representation of Characters, ISO-8859-1 Characters, Miscellaneous Character Operations, Characters
@section Internal Representation of Characters
@cindex internal representation, for character
such characters as @code{#\C-SOH}.}
MIT Scheme uses a 16-bit character code with 5 bucky bits. Normally,
-Scheme uses the least significant 7 bits of the character code to
-contain the @acronym{ASCII} representation for the character. The
-representation is expanded in order to allow for future accomodation of
-international character sets.
+Scheme uses the least significant 8 bits of the character code to
+contain the @acronym{ISO-8859-1} representation for the character. The
+representation is expanded in order to allow for the use of
+@acronym{UTF-16} in the future.
@deffn {procedure+} make-char code bucky-bits
@cindex construction, of character
(exclusive).
@end defvr
-@node ASCII Characters, Character Sets, Internal Representation of Characters, Characters
-@section ASCII Characters
+@node ISO-8859-1 Characters, Character Sets, Internal Representation of Characters, Characters
+@section ISO-8859-1 Characters
-MIT Scheme internally uses @acronym{ASCII} codes for @sc{i/o}, and stores
-character objects in a fashion that makes it convenient to convert
-between @acronym{ASCII} codes and characters. Also, character strings are
-implemented as byte vectors whose elements are @acronym{ASCII} codes; these
-codes are converted to character objects when accessed. For these
-reasons it is sometimes desirable to be able to convert between
-@acronym{ASCII} codes and characters.
+MIT Scheme internally uses @acronym{ISO-8859-1} codes for @sc{i/o}, and
+stores character objects in a fashion that makes it convenient to
+convert between @acronym{ISO-8859-1} codes and characters. Also,
+character strings are implemented as byte vectors whose elements are
+@acronym{ISO-8859-1} codes; these codes are converted to character
+objects when accessed. For these reasons it is sometimes desirable to
+be able to convert between @acronym{ISO-8859-1} codes and characters.
-@cindex ASCII character (defn)
-@cindex character, ASCII (defn)
-Not all characters can be represented as @acronym{ASCII} codes. A character
-that has an equivalent @acronym{ASCII} representation is called an @dfn{ASCII
-character}.
+@cindex ISO-8859-1 character (defn)
+@cindex character, ISO-8859-1 (defn)
+Not all characters can be represented as @acronym{ISO-8859-1} codes. A
+character that has an equivalent @acronym{ISO-8859-1} representation is
+called an @dfn{ISO-8859-1 character}.
+
+For historical reasons, the procedures that manipulate
+@acronym{ISO-8859-1} characters use the word ``@acronym{ASCII}'' rather
+than ``@acronym{ISO-8859-1}''.
@deffn {procedure+} char-ascii? char
-Returns the @acronym{ASCII} code for @var{char} if @var{char} has an
-@acronym{ASCII} representation; otherwise returns @code{#f}.
+Returns the @acronym{ISO-8859-1} code for @var{char} if @var{char} has an
+@acronym{ISO-8859-1} representation; otherwise returns @code{#f}.
-@findex char-bits
In the current implementation, the characters that satisfy this
-predicate are those in which the Control, Super, Hyper, and Top bucky
-bits are turned off. All characters for which the @code{char-bits}
-procedure returns @code{0} or @code{1} (i.e.@: no bucky bits, or just
-Meta) count as legal @acronym{ASCII} characters.
+predicate are those in which the bucky bits are turned off, and for
+which the character code is less than 256.
@end deffn
@deffn {procedure+} char->ascii char
-Returns the @acronym{ASCII} code for @var{char}. An error
+Returns the @acronym{ISO-8859-1} code for @var{char}. An error
@code{condition-type:bad-range-argument} is signalled if @var{char}
-doesn't have an @acronym{ASCII} representation.
+doesn't have an @acronym{ISO-8859-1} representation.
@findex condition-type:bad-range-argument
@end deffn
@deffn {procedure+} ascii->char code
-@var{Code} must be the exact integer representation of an @acronym{ASCII}
-code. This procedure returns the character corresponding to @var{code}.
+@var{Code} must be the exact integer representation of an
+@acronym{ISO-8859-1} code. This procedure returns the character
+corresponding to @var{code}.
@end deffn
-@node Character Sets, , ASCII Characters, Characters
+@node Character Sets, , ISO-8859-1 Characters, Characters
@section Character Sets
@cindex character set
@cindex set, of characters
MIT Scheme's character-set abstraction is used to represent groups of
characters, such as the letters or digits. Character sets may contain
-only @acronym{ASCII} characters; in the future this may be changed to
-allow the full range of characters.
+only @acronym{ISO-8859-1} characters; in the future this may be changed
+to allow the full range of characters.
There is no meaningful external representation for character sets; use
@code{char-set-members} to examine their contents. There is (at
@deffn {procedure+} char-set char @dots{}
@cindex construction, of character set
-Returns a character set consisting of the specified @acronym{ASCII}
+Returns a character set consisting of the specified @acronym{ISO-8859-1}
characters. With no arguments, @code{char-set} returns an empty
character set.
@end deffn
@deffn {procedure+} chars->char-set chars
Returns a character set consisting of @var{chars}, which must be a list
-of @acronym{ASCII} characters. This is equivalent to @code{(apply char-set
-@var{chars})}.
+of @acronym{ISO-8859-1} characters. This is equivalent to @code{(apply
+char-set @var{chars})}.
@end deffn
@deffn {procedure+} string->char-set string
@deffn {procedure+} ascii-range->char-set lower upper
@var{Lower} and @var{upper} must be exact non-negative integers
-representing @acronym{ASCII} character codes, and @var{lower} must be less
-than or equal to @var{upper}. This procedure creates and returns a new
-character set consisting of the characters whose @acronym{ASCII} codes are
-between @var{lower} (inclusive) and @var{upper} (exclusive).
+representing @acronym{ISO-8859-1} character codes, and @var{lower} must
+be less than or equal to @var{upper}. This procedure creates and
+returns a new character set consisting of the characters whose
+@acronym{ISO-8859-1} codes are between @var{lower} (inclusive) and
+@var{upper} (exclusive).
+
+For historical reasons, the name of this procedure refers to
+``@acronym{ASCII}'' rather than ``@acronym{ISO-8859-1}''.
@end deffn
@deffn {procedure+} predicate->char-set predicate
@var{Predicate} must be a procedure of one argument.
@code{predicate->char-set} creates and returns a character set
-consisting of the @acronym{ASCII} characters for which @var{predicate} is
-true.
+consisting of the @acronym{ISO-8859-1} characters for which
+@var{predicate} is true.
@end deffn
@deffn {procedure+} char-set-difference char-set1 char-set2
@end deffn
@deffn {procedure+} char-set-invert char-set
-Returns a character set consisting of the @acronym{ASCII} characters that are
-not in @var{char-set}.
+Returns a character set consisting of the @acronym{ISO-8859-1}
+characters that are not in @var{char-set}.
@end deffn
@node Strings, Lists, Characters, Top
@findex #\newline
@findex #\page
The effect of a backslash that doesn't precede a double quote or
-backslash is unspecified in standard Scheme, but MIT Scheme
-specifies the effect for three other characters: @code{\t}, @code{\n},
-and @code{\f}. These escape sequences are respectively translated into
-the following characters: @code{#\tab}, @code{#\newline}, and
-@code{#\page}. Finally, a backslash followed by exactly three octal
-digits is translated into the character whose @acronym{ASCII} code is those
+backslash is unspecified in standard Scheme, but MIT Scheme specifies
+the effect for three other characters: @code{\t}, @code{\n}, and
+@code{\f}. These escape sequences are respectively translated into the
+following characters: @code{#\tab}, @code{#\newline}, and @code{#\page}.
+Finally, a backslash followed by exactly three octal digits is
+translated into the character whose @acronym{ISO-8859-1} code is those
digits.
If a string literal is continued from one line to another, the string
@deffn procedure list->string char-list
@cindex list, converting to string
@findex string->list
-@var{Char-list} must be a list of @acronym{ASCII} characters.
+@var{Char-list} must be a list of @acronym{ISO-8859-1} characters.
@code{list->string} returns a newly allocated string formed from the
elements of @var{char-list}. This is equivalent to @code{(apply string
@var{char-list})}. The inverse of this operation is
@cindex vector, byte
@findex string-ref
-MIT Scheme implements strings as packed vectors of 8-bit @acronym{ASCII}
-bytes. Most of the string operations, such as @code{string-ref}, coerce
-these 8-bit codes into character objects. However, some lower-level
-operations are made available for use.
+MIT Scheme implements strings as packed vectors of 8-bit
+@acronym{ISO-8859-1} bytes. Most of the string operations, such as
+@code{string-ref}, coerce these 8-bit codes into character objects.
+However, some lower-level operations are made available for use.
@deffn {procedure+} vector-8b-ref string k
-Returns character @var{k} of @var{string} as an @acronym{ASCII} code.
-@var{K} must be a valid index of @var{string}.
+Returns character @var{k} of @var{string} as an @acronym{ISO-8859-1}
+code. @var{K} must be a valid index of @var{string}.
@example
@group
-(vector-8b-ref "abcde" 2) @result{} 99 @r{; ascii for `c'}
+(vector-8b-ref "abcde" 2) @result{} 99 @r{;c}
@end group
@end example
@end deffn
-@deffn {procedure+} vector-8b-set! string k ascii
-Stores @var{ascii} in element @var{k} of @var{string} and returns an
+@deffn {procedure+} vector-8b-set! string k code
+Stores @var{code} in element @var{k} of @var{string} and returns an
unspecified value. @var{K} must be a valid index of @var{string}, and
-@var{ascii} must be a valid @acronym{ASCII} code.
+@var{code} must be a valid @acronym{ISO-8859-1} code.
@end deffn
-@deffn {procedure+} vector-8b-fill! string start end ascii
-Stores @var{ascii} in elements @var{start} (inclusive) to @var{end}
+@deffn {procedure+} vector-8b-fill! string start end code
+Stores @var{code} in elements @var{start} (inclusive) to @var{end}
(exclusive) of @var{string} and returns an unspecified value.
-@var{Ascii} must be a valid @acronym{ASCII} code.
+@var{Code} must be a valid @acronym{ISO-8859-1} code.
@end deffn
-@deffn {procedure+} vector-8b-find-next-char string start end ascii
-@deffnx {procedure+} vector-8b-find-next-char-ci string start end ascii
-Returns the index of the first occurrence of @var{ascii} in the given
-substring; returns @code{#f} if @var{ascii} does not appear. The index
+@deffn {procedure+} vector-8b-find-next-char string start end code
+@deffnx {procedure+} vector-8b-find-next-char-ci string start end code
+Returns the index of the first occurrence of @var{code} in the given
+substring; returns @code{#f} if @var{code} does not appear. The index
returned is relative to the entire string, not just the substring.
-@var{Ascii} must be a valid @acronym{ASCII} code.
+@var{Code} must be a valid @acronym{ISO-8859-1} code.
@code{vector-8b-find-next-char-ci} doesn't distinguish uppercase and
lowercase letters.
@end deffn
-@deffn {procedure+} vector-8b-find-previous-char string start end ascii
-@deffnx {procedure+} vector-8b-find-previous-char-ci string start end ascii
-Returns the index of the last occurrence of @var{ascii} in the given
-substring; returns @code{#f} if @var{ascii} does not appear. The index
+@deffn {procedure+} vector-8b-find-previous-char string start end code
+@deffnx {procedure+} vector-8b-find-previous-char-ci string start end code
+Returns the index of the last occurrence of @var{code} in the given
+substring; returns @code{#f} if @var{code} does not appear. The index
returned is relative to the entire string, not just the substring.
-@var{Ascii} must be a valid @acronym{ASCII} code.
+@var{Code} must be a valid @acronym{ISO-8859-1} code.
@code{vector-8b-find-previous-char-ci} doesn't distinguish uppercase and
lowercase letters.
@end deffn
@deffn procedure length list
-Returns the length of @var{list}.
+Returns the length of @var{list}. Signals an error if @var{list} isn't
+a proper list.
@example
@group
is an alias for @code{delete-matching-items}.
@end deffn
+@deffn {procedure+} keep-matching-items! list predicate
+@deffnx {procedure+} delete-matching-items! list predicate
+These procedures are exactly like @code{keep-matching-items} and
+@code{delete-matching-items}, respectively, except that they
+destructively modify the @var{list} argument rather than allocating a
+new result.
+@end deffn
+
@deffn {procedure+} delq element list
@deffnx {procedure+} delv element list
@deffnx {procedure+} delete element list
@code{console-i/o-port}, but Scheme provides procedures that let you
change the current output port to be a file or string.
-All ports read or write only @acronym{ASCII} characters.
+All ports read or write only @acronym{ISO-8859-1} characters.
Every port is either an input port, an output port, or both. The
following predicates distinguish all of the possible cases.
projects / mit-scheme.git / commitdiff