cond

The if function takes one condition. If there are multiple conditions to test for then if is not the best option.

cond function can evaluate multiple conditions

(cond
  predicate1 expression-to-evaluate-when-predicate1-is-true
  predicate2 expression-to-evaluate-when-predicate2-is-true
  ...
  :else      expression-to-evaluate-when-all-above-are-false)

Reference: Conditional cond

To create the position function with cond

(def number 0)

(cond
  (= number 1) "1st"
  (= number 2) "2nd"
  (= number 3) "3rd"
  :else   (str number "th"))

Here is another example of using cond

(def x 0)

(cond
  (< x 10)    "x is smaller than 10"
  (< 10 x 20) "x is between 10 and 20"
  (< 20 x 30) "x is between 20 and 30"
  (< 30 x 40) "x is between 30 and 40"
  :else       "x is bigger than 40")