anchor.diff:  
   (defun prefix-length (x y)
     "Calculates length of common prefix for strings X and Y."
  -  (declare (type (simple-array character) x y)
  +  (declare (type simple-string x y)
              (inline length)
              (optimize (safety 0) (speed 3) (space 3)))
     (let ((x-len (length x))
  
positive.code: (defun overlap (x y)
    "This function calculates overlap coefficient between two given
  strings. Returned value is in range from 0 (no similarity) to 1 (exact match)."
    (declare (type (simple-array character) x y)
             (inline string-to-set intersection-length)
             (optimize (safety 0) (speed 3) (space 3)))
    (let ((x (string-to-set x))
  
negative.code: (defun jaro (x y)
    "Calculates Jaro distance between two strings. Returned value is in range
  from 0 (no similarity) to 1 (exact match)."
    (declare (type simple-string x y)
             (inline length fast-find)
             (optimize (safety 0) (speed 1) (space 3)))
    (let* ((x-len (length x))
  