(defn two-sum [nums target]
  (let [map (zipmap nums (range))]
    (loop [i 0]
      (if-let [idx (get map (- target (nums i)))]
        [i idx]
        (if (< (inc i) (count nums))
          (recur (inc i))
          [-1 -1]))))))

The code defines a function two-sum that takes a vector of numbers nums and a target number target. The function finds two numbers in the nums vector that add up to the target number and returns their indices as a vector.

The function starts by creating a map where the keys are the numbers in the nums vector and the values are their corresponding indices using the zipmap function.

Then, it enters a loop that iterates over the indices of the nums vector. Inside the loop, it checks if there is an index idx in the map corresponding to the difference between the target number and the number at the current index i in the nums vector. If such an index exists, it means that there are two numbers in the nums vector that add up to the target number. In this case, it returns a vector containing the current index i and the found index idx.

If there is no such index, it checks if the current index i is less than the total count of numbers in the nums vector. If it is, it increments i and continues to the next iteration of the loop.

If the loop finishes without finding a solution, it returns the vector [-1 -1] to indicate that no two numbers in the nums vector add up to the target number.

Testing:

(def nums [2 7 11 15])
(def target 9)

(two-sum nums target)
; [0 1]

In the given example, the nums vector is [2 7 11 15] and the target number is 9. The function finds that the numbers at indices 0 and 1 in the nums vector (2 and 7) add up to 9, so it returns the vector [0 1] as the result.