char-upcase, char-downcase, char-foldcase, char-titlecase - case conversion

---

LIBRARY

(import (rnrs))                     ;R6RS
(import (rnrs unicode))             ;R6RS
(import (scheme r5rs))              ;R7RS
(import (scheme char))              ;R7RS

SYNOPSIS

(char-upcase char)
(char-downcase char)
(char-foldcase char)
(char-titlecase char)               ;R6RS

DESCRIPTION

char-downcase

If the argument is an upper-case or title-case character, and if there is a single character that is its lower-case form, then char-downcase returns that character.

char-upcase

If the argument is a lower-case or title-case character, and there is a single character that is its upper-case form, then char-upcase returns that character.

char-foldcase

If the character has a case-folded character, then char-foldcase returns that character. Otherwise the character returned is the same as the argument. For Turkic characters İ (#\x130) and ı (#\x131), char-foldcase behaves as the identity function; otherwise char-foldcase is the same as char-downcase composed with char-upcase.

char-titlecase

If the argument is a lower-case or upper-case character, and there is a single character that is its title-case form, then char-titlecase returns that character. If the argument is not a title-case character and there is no single character that is its title-case form, then char-titlecase returns the upper-case form of the argument.

R7RS notes that language-sensitive folding and casing pairs are not used.

RETURN VALUES

EXAMPLES

(char-upcase #\i)     =>  #\I
(char-downcase #\i)   =>  #\i
(char-titlecase #\i)  =>  #\I
(char-foldcase #\i)   =>  #\i
;; The following might not be supported in R7RS implementations.
(char-upcase #\ß)     =>  #\ß
(char-downcase #\ß)   =>  #\ß
(char-titlecase #\ß)  =>  #\ß
(char-foldcase #\ß)   =>  #\ß
(char-upcase #\Σ)     =>  #\Σ
(char-downcase #\Σ)   =>  #\σ
(char-titlecase #\Σ)  =>  #\Σ
(char-foldcase #\Σ)   =>  #\σ
(char-upcase #\ς)     =>  #\Σ
(char-downcase #\ς)   =>  #\ς
(char-titlecase #\ς)  =>  #\Σ
(char-foldcase #\ς)   =>  #\σ

COMPATIBILITY

In R6RS implementations and other implementations that support Unicode, the behavior of these procedures depends on the supported Unicode version.

ERRORS

&assertion (R6RS)

The wrong number of arguments was passed or an argument was outside its domain.

R7RS

The assertions described above are errors. Implementations may signal an error, extend the procedure's domain of definition to include such arguments, or fail catastrophically.

SEE ALSO

STANDARDS

HISTORY

AUTHORS