macro_example.clj

;;; unless
user> (defmacro unless [cond then]
        `(if (not ~cond)
           ~then))
#'user/unless
user> (macroexpand-1 '(unless foo? bar))
(if (clojure.core/not foo?) bar)
;;; case
user> (defmacro case-table [k m]
        `(case ~k
           ~@(apply concat (eval m))))
#'user/case-table
user> 
user> (def table (atom {}))
#'user/table
user> (swap! table assoc :foo '(hoge "foo"))
{:foo (hoge "foo")}
user> (swap! table assoc :bar '(hoge "bar!"))
{:foo (hoge "foo"), :bar (hoge "bar!")}
user> (defn hoge [s] ,,,)
#'user/hoge
user> 
user> (defn fun1 [x]
        (let [y (case-table x @table)]
          ,,,))
#'user/fun1
user> (macroexpand-1 '(case-table x @table))
(clojure.core/case x :foo (hoge "foo") :bar (hoge "bar!"))
user> 
user> (swap! table dissoc :bar)
{:foo (hoge "foo")}
user> (swap! table assoc :baz '(hoge "baz!"))
{:foo (hoge "foo"), :baz (hoge "baz!")}
user> 
user> (defn fun2 [x]
        (let [y (case-table x @table)]
          ,,,))
#'user/fun2
user> (macroexpand-1 '(case-table x @table))
(clojure.core/case x :foo (hoge "foo") :baz (hoge "baz!"))

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