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;; Copyright (c) Stephen C. Gilardi. All rights reserved. The use and
;; distribution terms for this software are covered by the Eclipse Public
;; License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can
;; be found in the file epl-v10.html at the root of this distribution. By
;; using this software in any fashion, you are agreeing to be bound by the
;; terms of this license. You must not remove this notice, or any other,
;; from this software.
;;
;; File: cond.clj
;;
;; scgilardi (gmail)
;; 2 October 2008

(ns ^{:author "Stephen C. Gilardi"
       :doc "Extensions to the basic cond function."}
  clojure.contrib.cond)

(defmacro cond-let
  "Takes a binding-form and a set of test/expr pairs. Evaluates each test
one at a time. If a test returns logical true, cond-let evaluates and
returns expr with binding-form bound to the value of test and doesn't
evaluate any of the other tests or exprs. To provide a default value
either provide a literal that evaluates to logical true and is
binding-compatible with binding-form, or use :else as the test and don't
refer to any parts of binding-form in the expr. (cond-let binding-form)
returns nil."
  [bindings & clauses]
  (let [binding (first bindings)]
    (when-let [[test expr & more] clauses]
      (if (= test :else)
        expr
        `(if-let [~binding ~test]
           ~expr
           (cond-let ~bindings ~@more))))))
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