Macro to retry executing some code in case of an exception

with-retries.clj

(ns test)

(defn try-times
  "Try executing a thunk `retries` times."
  [retries thunk]
  (if-let [res (try
                 [(thunk)]
                 (catch Exception e ; can be any exception
                   (when (zero? retries)
                     (throw e))))]
    (res 0)
    (recur (dec retries) thunk)))


(defmacro with-retries
  "Try executing `body`. In case of an exception, retry max `retries` times."
  [retries & body]
  `(try-times ~retries (fn [] ~@body)))


(comment
(defn some-io-operation
  "Some read I/O operation that could throw an IOException."
  []
  (println "WOULD do a read operation"))

(with-retries 10 (some-io-operation))
)

Out of interest, why do you evaluate the thunk within a vector on line 7? Is it necessary?

Sam, yes, it's required. Otherwise, it won't work for functions that return nil.