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Index
Constituent Characters Character Syntax Types Invalid Characters

Constituent Traits

Every character has one or more constituent traits that define how the character is to be interpreted by the Lisp reader when the character is a constituent character. These constituent traits are alphabetic_2, digit, package marker, plus sign, minus sign, dot, decimal point, ratio marker, exponent marker, and invalid. Figure~2–8 shows the constituent traits of the standard characters and of certain semi-standard characters; no mechanism is provided for changing the constituent trait of a character. Any character with the alphadigit constituent trait in that figure is a digit if the current input base is greater than that character’s digit value, otherwise the character is alphabetic_2. Any character quoted by a single escape is treated as an alphabetic_2 constituent, regardless of its normal syntax.

Character Constituent traits Character Constituent traits
 Backspaceinvalid{alphabetic_2
 Tabinvalid*}alphabetic_2
 Newlineinvalid*+alphabetic_2, plus sign
 Linefeedinvalid*-alphabetic_2, minus sign
 Pageinvalid*.alphabetic_2, dot, decimal point
 Returninvalid*/alphabetic_2, ratio marker
 Spaceinvalid*A, aalphadigit
 !alphabetic_2B, balphadigit
 "alphabetic_2*C, calphadigit
 #alphabetic_2*D, dalphadigit, double-float exponent marker
 $alphabetic_2E, ealphadigit, float exponent marker
 %alphabetic_2F, falphadigit, single-float exponent marker
 &alphabetic_2G, galphadigit
 ’alphabetic_2*H, halphadigit
 (alphabetic_2* I, ialphadigit
 )alphabetic_2* J, jalphadigit
 *alphabetic_2K, kalphadigit
 ,alphabetic_2* L, lalphadigit, long-float exponent marker
 0-9alphadigitM, malphadigit
 :package markerN, nalphadigit
 ;alphabetic_2* O, oalphadigit
 <alphabetic_2P, palphadigit
 =alphabetic_2Q, qalphadigit
 >alphabetic_2R, ralphadigit
 ?alphabetic_2S, salphadigit, short-float exponent marker
 @alphabetic_2T, talphadigit
 [alphabetic_2U, ualphadigit
 \alphabetic_2* V, valphadigit
 ]alphabetic_2W, walphadigit
 ^alphabetic_2X, xalphadigit
 _alphabetic_2Y, yalphadigit
 ‘alphabetic_2*  Z, zalphadigit
 |alphabetic_2* Ruboutinvalid
 ~alphabetic_2
Figure 2–8: Constituent Traits of Standard Characters and Semi-Standard Characters

The interpretations in this table apply only to characters whose syntax type is constituent. Entries marked with an asterisk (*) are normally shadowed_2 because the indicated characters are of syntax type whitespace_2, macro character, single escape, or multiple escape; these constituent traits apply to them only if their syntax types are changed to constituent.

Backlinks

Character Syntax Types, set-syntax-from-char