add lesson 25

Author: astynax

otus-25/project.clj

@@ -0,0 +1,9 @@
+(defproject otus-25 "0.1.0-SNAPSHOT"
+  :description "FIXME: write description"
+  :url "http://example.com/FIXME"
+  :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
+            :url "https://www.eclipse.org/legal/epl-2.0/"}
+  :dependencies [[org.clojure/clojure "1.11.1"]]
+  :target-path "target/%s"
+  :profiles {:uberjar {:aot :all
+                       :jvm-opts ["-Dclojure.compiler.direct-linking=true"]}})

otus-25/src/otus_25/core.clj

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+(ns otus-25.core
+  (:require [clojure.walk :refer [macroexpand-all]])
+  (:gen-class))
+
+;; * Макросы
+
+;; ** quote и eval
+
+(quote (asd qwe hjk [123 :foo (asd)]))
+
+(eval (concat (quote (+ 1) (list 2 3))))
+
+;; ** defmacro
+
+;; (append-2-3 (+ 1)) => (+ 1 2 3)
+;; (append-2-3 (println)) => (println 2 3)
+(defmacro append-2-3 [expr]
+  (concat expr (list 2 3)))
+
+;; ** Отладка
+
+(macroexpand-1 '(append-2-3 (println)))
+(macroexpand '(append-2-3 (println)))
+
+(macroexpand-1 '(append-2-3 (when true)))
+(macroexpand '(append-2-3 (when true)))
+
+(macroexpand-all '(cond (< 1 2) 42
+                        nil :foo
+                        true :oops))
+
+;; ** syntax-quote
+
+(let [x 42] `(+ ~(+ 3 4) ~x ~x))
+
+(defmacro append-2-3 [expr]
+  `(~@expr 2 3))
+
+(defmacro when? [cond & body]
+  `(if ~cond
+     (do ~@(apply concat (map (fn [_] body)) [1 2 3]))))
+
+(macroexpand-1 (when? true
+                 (println 1)
+                 (println 2)))
+
+;; ** анафорические макросы
+
+(defmacro inject-x [& body]
+  `(let [~'x 42] ~@body))
+
+(comment
+  (inject-x (println x)))
+
+;; ** gensym и #
+
+(defmacro tap [expr]
+  (let [name (gensym)]
+    `(let [~name ~expr]
+       (println '~expr "=>" ~name)
+       ~name)))
+
+(comment
+  (tap (+ 1 2)))
+
+(defmacro tap [expr]
+  `(let [name# ~expr]
+     (println '~expr "=>" name#)
+     name#))
+
+(macroexpand-1
+ '(tap (+ 1 3)))
+
+;; ** &env и &form
+
+(comment
+  (@#some-macro '(some-macro x) {'x nil} 'x))