(string-contains-ci str pattern)

string-contains-ci return the index of the first case-insensitive occurrence of pattern in str

Parameter	Description
str	Input string
pattern	The pattern string to look for

Example

Example 1: String comparisons performed in a search field of an application

(if (fx= (string-length text) 1)  
  ;; If only one character, just display things that start with it
  (lambda (str1 str2) (string-ci=? (substring str1 0 1) str2))
  ;; Otherwise display all that contain it
  (lambda (str1 str2) (string-contains-ci str1 str2))))