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;; Copyright (c) Jason Wolfe. 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.
;;
;; map_utils.clj
;;
;; Utilities for operating on Clojure maps.
;;
;; jason at w01fe dot com
;; Created 25 Feb 2009
(ns clojure.contrib.map-utils)
(defmacro lazy-get
"Like get, but doesn't evaluate not-found unless it is needed."
[map key not-found]
`(if-let [pair# (find ~map ~key)]
(val pair#)
~not-found))
(defn safe-get
"Like get, but throws an exception if the key is not found."
[map key]
(lazy-get map key
(throw (IllegalArgumentException. (format "Key %s not found in %s" key map)))))
(defn safe-get-in
"Like get-in, but throws an exception if any key is not found."
[map ks]
(reduce safe-get map ks))
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