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:
ClassCastException java.lang.Long cannot be cast to clojure.lang.IFn
The Code
(defn calculate-salary
[years salary]
(if (= years 0)
(salary)
(calculate-salary (- years 1) (* salary 2))))
I'm very new to Clojure so I'm sure its something simple, but I just can't seem to figure it out.
The error's meaning shouldn't be too hard to sort out: a number is being used where a function is expected.
Parenthesis in Clojure are not a grouping construct, they are used primarily to invoke function calls. If you change (salary) to salary you will return the number rather than attempting to call it as a no-argument function.
(repeatedly (read)) instead of (repeatedly read).Since you are new I rewrote your function to be a bit more idiomatic. Also, it uses recur so it will not consume the call stack.
(defn calculate-salary
[years salary]
(if (zero? years)
salary
(recur (dec years) (* salary 2))))
Notice the use of the zero? predicate, recur, and dec
EDIT: typos and grammar
This
(salary)
is a function call, but salary is not a function -- it's a number.
The solution is to not wrap it in parentheses:
(if (= years 0) salary (calculate-salary (- years 1) (* salary 2)))
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.
