comparison src/clojure/contrib/macros.clj @ 10:ef7dbbd6452c

added clojure source goodness
author Robert McIntyre <rlm@mit.edu>
date Sat, 21 Aug 2010 06:25:44 -0400
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9:35cf337adfcf 10:ef7dbbd6452c
1 ;; Various useful macros
2 ;;
3 ;; Everybody is invited to add their own little macros here!
4 ;;
5 ;; The use and distribution terms for this software are covered by the
6 ;; Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
7 ;; which can be found in the file epl-v10.html at the root of this
8 ;; distribution. By using this software in any fashion, you are
9 ;; agreeing to be bound by the terms of this license. You must not
10 ;; remove this notice, or any other, from this software.
11
12 (ns
13 ^{:author "Konrad Hinsen"
14 :doc "Various small macros"}
15 clojure.contrib.macros)
16
17 ;; By Konrad Hinsen
18 (defmacro const
19 "Evaluate the constant expression expr at compile time."
20 [expr]
21 (eval expr))
22
23 ;; By Konrad Hinsen
24 ; This macro is made obsolete by Clojure's built-in letfn. I renamed it to
25 ; letfn- (to avoid a name clash) but leave it in for a while, since its
26 ; syntax is not quite the same as Clojure's. Expect this to disappear
27 ; in the long run!
28 (defmacro letfn-
29 "OBSOLETE: use clojure.core/letfn
30 A variant of let for local function definitions. fn-bindings consists
31 of name/args/body triples, with (letfn [name args body] ...)
32 being equivalent to (let [name (fn name args body)] ...)."
33 [fn-bindings & exprs]
34 (let [makefn (fn [[name args body]] (list name (list 'fn name args body)))
35 fns (vec (apply concat (map makefn (partition 3 fn-bindings))))]
36 `(let ~fns ~@exprs)))
37
38 ;; By Konrad Hinsen
39
40 (defn- unqualified-symbol
41 [s]
42 (let [s-str (str s)]
43 (symbol (subs s-str (inc (.indexOf s-str (int \/)))))))
44
45 (defn- bound-var?
46 [var]
47 (try
48 (do (deref var) true)
49 (catch java.lang.IllegalStateException e false)))
50
51 (defn- fns-from-ns
52 [ns ns-symbol]
53 (apply concat
54 (for [[k v] (ns-publics ns)
55 :when (and (bound-var? v)
56 (fn? @v)
57 (not (:macro (meta v))))]
58 [k (symbol (str ns-symbol) (str k))])))
59
60 (defn- expand-symbol
61 [ns-or-var-sym]
62 (if (= ns-or-var-sym '*ns*)
63 (fns-from-ns *ns* (ns-name *ns*))
64 (if-let [ns (find-ns ns-or-var-sym)]
65 (fns-from-ns ns ns-or-var-sym)
66 (list (unqualified-symbol ns-or-var-sym) ns-or-var-sym))))
67
68 (defmacro with-direct-linking
69 "EXPERIMENTAL!
70 Compiles the functions in body with direct links to the functions
71 named in symbols, i.e. without a var lookup for each invocation.
72 Symbols is a vector of symbols that name either vars or namespaces.
73 A namespace reference is replaced by the list of all symbols in the
74 namespace that are bound to functions. If symbols is not provided,
75 the default value ['clojure.core] is used. The symbol *ns* can be
76 used to refer to the current namespace."
77 {:arglists '([symbols? & body])}
78 [& body]
79 (let [[symbols body] (if (vector? (first body))
80 [(first body) (rest body)]
81 [['clojure.core] body])
82 bindings (vec (mapcat expand-symbol symbols))]
83 `(let ~bindings ~@body)))
84