(examples-for detect
  ("returns first matching item in a list"
   (detect (fn (x) (eq? (len x) 2))
           (list "foo" "bar" "xx" "pp"))
   "xx")

  ("returns nil when nothing matches"
   (detect (fn (x) (eq? (len x) 20))
           (list "foo" "bar" "xx" "pp"))
   nil)

  ;; kind of pointless
  ("returns nil if nil is the matching item"
   (detect no (list "foo" "bar" nil "pp"))
   nil)

  ("returns item if it's an atom and matches"
   (detect (fn (x) (eq? (len x) 2)) "zz")
   "zz")

  ("returns nil if it's an atom and doesn't match"
   (detect (fn (x) (eq? (len x) 20))
           "zz")
   nil))