Getting Clojure

Staying Out of Trouble

One thing to keep in mind as you dive into Java interop is that while we can use .method and class/staticMethod in place of functions, they are not functions. They are, instead, special forms, more or less hardwired into Clojure. In particular, you cannot bind a method name:

;; Nope. Nope. Nope.

(def count-method .count)

All is not lost, however: you can use the built-in memfn function to turn a method name into a function. For example, while .exists is not a function, (memfn exists) is. This can be useful when you need a function value. If, for instance, you had a collection of File instances:

(def files [(File. "authors.txt") (File. "titles.txt")])

and you needed the parallel collection of Booleans indicating ...