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;; Various useful macros
;;
;; Everybody is invited to add their own little macros here!
;;
;; 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.
(ns clojure.contrib.macros)
;; By Konrad Hinsen
(defmacro const
"Evaluate the constant expression expr at compile time."
[expr]
(eval expr))
;; By Konrad Hinsen
(defmacro letfn
"A variant of let for local function definitions. fn-bindings consists
of name/args/body triples, with (letfn [name args body] ...)
being equivalent to (let [name (fn name args body)] ...)."
[fn-bindings & exprs]
(let [makefn (fn [[name args body]] (list name (list 'fn name args body)))
fns (vec (apply concat (map makefn (partition 3 fn-bindings))))]
`(let ~fns ~@exprs)))
;; By Konrad Hinsen
(defmacro lazy-and-standard-branch
"Comile the first expression in the lazy branch of Clojure, and the second
one in the standard branch."
[lazy-expr standard-expr]
(if (find (ns-map (find-ns 'clojure.core)) 'lazy-seq)
lazy-expr
standard-expr))
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