let% provides a mixed let + letfn macro. No mutual recursion tho

letletfn.clj

;; largely @emccue's implementation in https://clojurians-log.clojureverse.org/clojure on 2021-05-04
;; with a few fixes and adjustments

(defmacro let% [clauses & body]
  (loop [clauses clauses
         bindings []]
    (if (empty? clauses)
      `(let ~bindings ~@body)
      (let [[fc & rcs] clauses]
        (if (list? fc)
          (recur rcs
                 (-> bindings
                     (conj (first fc))
                     (conj (cons `fn fc))))
          (if (>= (count clauses) 2)
            (recur (rest rcs)
                   (-> bindings
                       (conj fc)
                       (conj (second clauses))))
            (throw (ex-info "Not enough clauses in let%" {:clauses clauses}))))))))

(let% [bar           1
       (foo [x y z] [x y z])
       {:keys [baz]} {:baz 2}
       [_ _ qux]     [0 0 3 4]]

      (foo bar baz qux))
  
;; => [1 2 3]