ClassCastException java.lang.Long cannot be cast to clojure.lang.IFn

Question

I have a function that takes the number of years and salary, then recursively doubles the salary until years is exhausted. However, I keep getting this error:

Answer 1

You need to remove the brackets from around salary in your if condition:

(if (= years 0)
        salary
        (calculate-salary (- years 1) (* salary 2))

the form (f arg1 arg2 ..) attempts to call f as a function with arg1, arg2 ... as arguments. Therefore (salary) attempts to invoke salary (a long) as a function with no arguments, hence the error.