t3x.org / sketchy / library / s-cieqp.html
SketchyLISP
Reference
  Copyright (C) 2006
Nils M Holm

string-ci=?

Conformance: R5RS

Purpose: Case-insensitively test whether two strings are equal.

Arguments:
X - string
Y - string

Implementation:

(define (string-ci=? x y)
  (letrec
    ((ci-eq? (lambda (x y)
      (cond ((null? x) (null? y))
        ((null? y) #f)
        ((char-ci=? (car x) (car y))
          (ci-eq? (cdr x) (cdr y)))
        (#t #f)))))
    (ci-eq? (string->list x)
            (string->list y))))

Example:

(string-ci=? "xyz" "XYZ") 
=> #t

See also:
string=?, string-ci<?, string-ci>?, string-ci<=?, string-ci>=?, char-ci=?, equal?.