Higher Order functions

Functions can be used as an arguments to other functions. This is possible because a function always evaluates to a value.

It is also stated that higher order functions should return a function, usually when thinking in typed lambda calculus although some dispute this requirement.

Note Create a named function as a higher order function, which adds a value to a number twice

(defn twice [function x]
  (function (function x)))

(twice #(+ % 3) 7) ;13

Note Return the even numbers from 1 to 10

(filter
 even?
 (range 1 10))

References

• Writing Elegant Clojure code using Higher Order functions