Monads

Demonstrate in your programming language the following:

 1. Construct a Monad (preferably the Option/Maybe Monad)
 2. Make two functions, each which take a number and return a wrapped number
 3. Compose the two functions with bind

Clojure

List Monad:

<lang clojure> (defn bind [coll f] (apply vector (mapcat f coll))) (defn unit [e] (vector e))

(def vecstr (comp vector str)) (defn doubler [n] [n n])

(bind (bind [3 4 5] vecstr) doubler) ; evaluates to ["3" "3" "4" "4" "5" "5"] (-> [3 4 5]

 (bind vecstr)
 (bind doubler)) ; also evaluates to ["3" "3" "4" "4" "5" "5"]

</lang>