CLHS: Issue CHARACTER-PROPOSAL Writeup

Issue CHARACTER-PROPOSAL Writeup

This is KMP's plain-text transcription of the issues which comprise

the Character Proposal. This isn't what was voted on, but it may be

easier to use than the one that was, since it's not full of TeX codes.

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Proposal 2.0.1: [Passed 03/89]

The terminology introduced in this proposal will be included

in the language specification at the discretion of the editor.

Proposal 2.1.1: [Alternative A, Passed as Modified 03/89]

Remove all discussion of attributes from

the language specification. Add the following discussion:

``Earlier versions of Common LISP incorporated FONT and BITS as

attributes of character objects. These and other supported

attributes are considered implementation-defined attributes and

if supported by an implementation effect the action of selected

functions.''

All types, constants and functions dealing with the BITS and

FONT attributes are either removed or modified as follows:

* Modify CHAR-=: If two characters differ in any implementation-defined

attributes, then they are not CHAR-=.

* Modify CHAR-<: If two characters have identical implementation-defined

attributes, then their ordering by CHAR< is consistent with the

numerical ordering by the predicate < on their code. (Similarly for

CHAR>, CHAR>= and CHAR<=.)

* Modify CHAR-EQUAL: The effect, if any, on CHAR-EQUAL of each

implementation-defined attribute has to be specified as part of the

definition of that attribute (and similarly for CHAR-NOT-EQUAL,

CHAR-LESSP, CHAR-GREATERP, CHAR-NOT-GREATERP, CHAR-NOT-LESSP).

* Modify CHAR-UPCASE and CHAR-DOWNCASE: The effect of CHAR-UPCASE and

CHAR-DOWNCASE is to preserve implementation-defined attributes.

* Modify READ: It is implementation dependent which attributes are

removed from symbol names. It is implementation dependent which

attributes are removed from characters within double quotes.

* Modify INTERN: It is implementation dependent which

implementation-defined attributes are removed.

* Modify DIGIT-CHAR: remove the optional FONT argument.

* Modify CODE-CHAR: remove the optional FONT and BIT arguments.

* Remove CHAR-FONT-LIMIT

* Remove CHAR-BITS-LIMIT

* Remove INT-CHAR

* Remove CHAR-INT

<<This removal is later rescinded by 2.1.2. See below. -kmp 2-Aug-89>>

* Remove CHAR-BITS

* Remove CHAR-FONT

* Remove MAKE-CHAR

* Remove CHAR-CONTROL-BIT

* Remove CHAR-META-BIT

* Remove CHAR-SUPER-BIT

* Remove CHAR-HYPER-BIT

* Remove CHAR-BIT

* Remove SET-CHAR-BIT

* Remove STRING-CHAR and STRING-CHAR-P

* Modify readtable: If implementation-defined attributes are supported,

an implementation need not (but may) allow for such characters to have

syntax descriptions in the readtable. Otherwise, all characters are

representable in the readtable.

Proposal 2.1.2: [Alternative B, Passed as Modified 03/89]

This is identical to all of Alternative A (above) except that the function

CHAR-INT is retained. CHAR-INT returns a non-negative integer encoding the

character object. The manner in which the integer is computed is

implementation dependent. In contrast to SXHASH, the result is not

guaranteed independent of the particular "incarnation" or "core image".

Proposal 2.2.1: [Passed 03/89]

The discussion of standard characters is replaced by the following:

Common LISP requires all implementations to support and document

a STANDARD character subrepertoire. The Common LISP standard character

subrepertoire consists of a newline, #\Newline; the graphic space

character #\Space; and the following additional ninety-four graphic

characters or their equivalents:

Note: #\Space and #\Newline are omitted. Graphic labels and

descriptions are from ISO 6937/2. The first letter of the

graphic Id categorizes the character as follows:

L - Latin, N - Numeric, S - Special.

Id Glyph Name or description Id Glyph Name or description

LA01 a small a ND01 1 digit 1

LA02 A capital A ND02 2 digit 2

LB01 b small b ND03 3 digit 3

LB02 B capital B ND04 4 digit 4

LC01 c small c ND05 5 digit 5

LC02 C capital C ND06 6 digit 6

LD01 d small d ND07 7 digit 7

LD02 D capital D ND08 8 digit 8

LE01 e small e ND09 9 digit 9

LE02 E capital E ND10 0 digit 0

LF01 f small f SC03 $ dollar sign

LF02 F capital F SP02 ! exclamation mark

LG01 g small g SP04 " quotation mark

LG02 G capital G SP05 ' apostrophe

LH01 h small h SP06 ( left parenthesis

LH02 H capital H SP07 ) right parenthesis

LI01 i small i SP08 , comma

LI02 I capital I SP09 _ low line

LJ01 j small j SP10 - hyphen or minus sign

LJ02 J capital J SP11 . full stop, period

LK01 k small k SP12 / solidus

LK02 K capital K SP13 : colon

LL01 l small l SP14 ; semicolon

LL02 L capital L SP15 ? question mark

LM01 m small m SA01 + plus sign

LM02 M capital M SA03 < less-than sign

LN01 n small n SA04 = equals sign

LN02 N capital N SA05 > greater-than sign

LO01 o small o SM01 # number sign

LO02 O capital O SM02 % percent sign

LP01 p small p SM03 & ampersand

LP02 P capital P SM04 * asterisk

LQ01 q small q SM05 @ commercial at

LQ02 Q capital Q SM06 [ left square bracket

LR01 r small r SM07 \ reverse solidus

LR02 R capital R SM08 ] right square bracket

LS01 s small s SM11 { left curly bracket

LS02 S capital S SM13 | vertical bar

LT01 t small t SM14 } right curly bracket

LT02 T capital T SD13 ` grave accent

LU01 u small u SD15 ^ circumflex accent

LU02 U capital U SD19 ~ tilde

LV01 v small v

LV02 V capital V

LW01 w small w

LW02 W capital W

LX01 x small x

LX02 X capital X

LY01 y small y

LY02 Y capital Y

LZ01 z small z

LZ02 Z capital Z

Proposal 2.3.1: [Passed as Modified 03/89]

The following type definitions are added:

Define BASE-CHARACTER as (UPGRADED-ARRAY-ELEMENT-TYPE 'STANDARD-CHAR)

and EXTENDED-CHARACTER as type (AND CHARACTER (NOT BASE-CHARACTER)).

Characters of type BASE-CHARACTER are referred to as ``base characters''.

Characters of type EXTENDED-CHARACTER are referred to as

``extended characters.''

Proposal 2.3.2: [Passed 03/89]

The STRING type is defined as a union type. More precisely, a string

is a specialized vector whose elements are of type CHARACTER or a

subtype of CHARACTER. STRING used as a type specifier for object

creation means (VECTOR CHARACTER).

Proposal 2.3.3: [Passed as Modified 03/89]

The following string subtypes are distinguished with standardized names.

* BASE-STRING is equivalent to (VECTOR BASE-CHARACTER).

Strings of type BASE-STRING are referred to as ``base strings.''

* BASE-STRING is valid as a type specifier that abbreviates.

Proposal 2.3.4: [Passed as Modified 03/89]

Define SIMPLE-STRING as a union type. A simple string is a specialized

simple one dimensional array whose elements are of type CHARACTER or a

subtype of CHARACTER. SIMPLE-STRING used as a type specifier for object

creation means (SIMPLE-ARRAY CHARACTER size).

Proposal 2.3.5: [Passed as Modified 03/89]

The following simple string subtypes are distinguished with standardized

names:

* SIMPLE-BASE-STRING is equivalent to (SIMPLE-ARRAY BASE-CHARACTER (*)).

SIMPLE-BASE-STRING is a subtype of BASE-STRING.

* SIMPLE-BASE-STRING is valid as a type specifier that abbreviates.

Proposal 2.3.6: [Passed 03/89]

Extend the MAKE-STRING function to allow an ELEMENT-TYPE keyword argument:

* MAKE-STRING size &KEY :initial-element :element-type [Function]

This returns a simple string of length SIZE, each of whose characters

has been initialized to the :INITIAL-ELEMENT argument. If an

:INITIAL-ELEMENT argument is not specified, then the string will be

initialized in an implementation-dependent way. The :ELEMENT-TYPE

argument names the type of the elements of the string; a string is

constructed of the most specialized type that can accommodate elements

of the given type. If :ELEMENT-TYPE is omitted, the type CHARACTER

is the default.

Proposal 2.4.1: [Passed 03/89]

Common LISP character codes are composed from a character script and

a character label. The convention by which a character label and

character script compose a character code is implementation dependent.

Proposal 2.4.2: [Passed as Modified 06/89]

An implementation must document the scripts it supports. For each script

supported the documentation must include at least the following:

* Character Labels, Glyphs, and Descriptions. Character labels must

be uniquely named using only Latin capital letters A-Z, hyphen and

digits 0-9.

* Effect of CHAR-UPCASE and CHAR-DOWNCASE.

* Reader canonicalization and format directives.

Note: Any mechanisms by which the READ function treats distinct

characters as equivalent.

* Effect of character predicates. In particular,

- CHAR-EQUAL and other case-insensitive character predicates.

* Interaction with File I/O. In particular, the coded character

sets (e.g., ISO8859/1-1987) and external encoding schemes

supported are documented.

Proposal 2.4.3: [Passed as Modified 06/89]

Every character repertoire name is a type specifier and a subtype of

type CHARACTER.

Proposal 2.5.2: [Passed as Modified 06/89]

Add an additional keyword argument to OPEN and a new function to query

external file format:

* :EXTERNAL-FORMAT keyword argument on OPEN which specifies an

implementation recognized scheme for representing characters in files.

The default value is :DEFAULT and is implementation defined but must

support the base characters.

If the argument is not recognized by the implementation, an error is

signalled. This argument is provided for input, output, and bidirectional

streams. It is an error to write a character which cannot be represented

using the given file format. (This excludes the #\Newline character.

Implementations must provide appropriate line division behavior for all

character streams.)

* STREAM-EXTERNAL-FORMAT stream [Function]

STREAM-EXTERNAL-FORMAT returns the implementation recognized format of

the specified file.

Proposal 2.5.4: [Alternative A, Passed 06/89]

The default for the :ELEMENT-TYPE argument of OPEN is CHARACTER.

Proposal 2.5.6: [Passed as Modified 06/89]

Modify the following functions:

* WITH-OUTPUT-TO-STRING. A new keyword argument :ELEMENT-TYPE is added

which defaults to CHARACTER. If a string argument is provided, the

:ELEMENT-TYPE argument is ignored. A string argument of NIL means

no initial string argument is provided. If no string argument is

provided, produces a stream that accepts all characters of the

indicated type and returns a string of the indicated element type.

* MAKE-STRING-OUTPUT-STREAM. A new keyword argument :ELEMENT-TYPE is

added which defaults to CHARACTER. MAKE-STRING-OUTPUT-STREAM returns

an output stream that accepts all characters of the indicated type

and returns (via GET-OUTPUT-STREAM-STRING) a string of the indicated

type.

Proposal 2.5.7: [Passed as Modified 06/89]

Add the following function:

* FILE-STRING-LENGTH file-stream object [Function]

FILE-STRING-LENGTH returns a non-negative integer which represents

the difference between what (FILE-POSITION file-stream) would be

after writing the OBJECT and its current value, or NIL if this cannot

be determined. OBJECT must be a string or character.

This return value depends on the current state of the stream, that

is, two calls to FILE-STRING-LENGTH with the same stream and object

may return different values.

Misc effects on CLtL...

Proposal 2.6.1: [Passed 03/89]

Chapter 2 Data Types (Page 12)

Replace:

provides for a

rich character set, including ways to represent characters of various

type styles.

with:

provides support for international language characters as well

as characters used in specialized arenas, eg. mathematics.

Proposal 2.6.2: [Passed as Modified 03/89]

Chapter 2 Symbols (Page 25)

Clarify:

A symbol may have any character in its print name.

Proposal 2.6.3: [Passed 03/89]

Chapter 10 Symbols (Page 163)

Replace:

It is ordinarily not permitted to alter a symbol's print name.

with:

It is an error to alter a symbol's print name.

Proposal 2.6.4: [Passed 03/89]

Chapter 10 The Print Name (Page 168)

Replace:

It is an extremely bad idea to modify a string being used

as the print name of a symbol.

with:

It is an error to modify a string being used

as the print name of a symbol.

Proposal 2.6.5: [Passed 03/89]

Chapter 14 Simple Sequence Functions (Page 249, make-sequence)

Append:

If type STRING is specified, the result is equivalent to MAKE-STRING.