ANSI Common Lisp ![]() ![]() ![]() 6.1.6.1 Examples of WHEN clause;; Signal an exceptional condition. (loop for item in '(1 2 3 a 4 5) when (not (numberp item)) return (cerror "enter new value" "non-numeric value: ~s" item)) Error: non-numeric value: A ;; The previous example is equivalent to the following one. (loop for item in '(1 2 3 a 4 5) when (not (numberp item)) do (return (cerror "Enter new value" "non-numeric value: ~s" item))) Error: non-numeric value: A
;; This example parses a simple printed string representation from ;; BUFFER (which is itself a string) and returns the index of the ;; closing double-quote character. (let ((buffer "\"a\" \"b\"")) (loop initially (unless (char= (char buffer 0) #\") (loop-finish)) for i of-type fixnum from 1 below (length (the string buffer)) when (char= (char buffer i) #\") return i)) |