Mercurial > lasercutter

     1 ;;  Copyright (c) Stephen C. Gilardi. All rights reserved.  The use and

     2 ;;  distribution terms for this software are covered by the Eclipse Public

     3 ;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can

     4 ;;  be found in the file epl-v10.html at the root of this distribution.  By

     5 ;;  using this software in any fashion, you are agreeing to be bound by the

     6 ;;  terms of this license.  You must not remove this notice, or any other,

     7 ;;  from this software.

     8 ;;

     9 ;;  File: cond.clj

    10 ;;

    11 ;;  scgilardi (gmail)

    12 ;;  2 October 2008

    13 

    14 (ns ^{:author "Stephen C. Gilardi"

    15        :doc "Extensions to the basic cond function."} 

    16   clojure.contrib.cond)

    17 

    18 (defmacro cond-let

    19   "Takes a binding-form and a set of test/expr pairs. Evaluates each test

    20   one at a time. If a test returns logical true, cond-let evaluates and

    21   returns expr with binding-form bound to the value of test and doesn't

    22   evaluate any of the other tests or exprs. To provide a default value

    23   either provide a literal that evaluates to logical true and is

    24   binding-compatible with binding-form, or use :else as the test and don't

    25   refer to any parts of binding-form in the expr. (cond-let binding-form)

    26   returns nil."

    27   [bindings & clauses]

    28   (let [binding (first bindings)]

    29     (when-let [[test expr & more] clauses]

    30       (if (= test :else)

    31         expr

    32         `(if-let [~binding ~test]

    33            ~expr

    34            (cond-let ~bindings ~@more))))))
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
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