From 0c0ab4e45772af361b3c3581d3215605256e8ee4 Mon Sep 17 00:00:00 2001
From: Jaskirat <me@jaskirat.info>
Date: Tue, 8 Feb 2011 17:21:11 +0530
Subject: [PATCH] Added macros.clj and updated the path_to_answer_sheet &
 path_to_enlightenment for the same.

---
 src/koans/macros.clj          | 47 +++++++++++++++++++++++++++++++++++
 src/path_to_answer_sheet.clj  | 10 ++++++++
 src/path_to_enlightenment.clj |  3 ++-
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 src/koans/macros.clj

diff --git a/src/koans/macros.clj b/src/koans/macros.clj
new file mode 100644
index 0000000..a72d835
--- /dev/null
+++ b/src/koans/macros.clj
@@ -0,0 +1,47 @@
+"Macros are also just functions!"
+(defmacro hello [x]
+  (str "Hello, " x))
+
+  "Create a list and use it to be eval-ed at run time"
+(defmacro infix [form]
+  (list (second form) (first form) (nth form 2)))
+
+"Sometimes it is easier to handcraft it ..."
+(defmacro infix-better [form]
+  `(~(second form)
+    __
+    __ ))
+
+"Macro in a macro until you get a stack overflow! ;)"
+(defmacro r-infix [form]
+  (list (second form)
+        (if (instance? clojure.lang.PersistentList (first form))
+            `(r-infix ~(first form))
+            (first form))
+        (if (instance? clojure.lang.PersistentList (nth form 2))
+            `(r-infix ~(nth form 2))
+            (nth form 2))
+        ))
+
+
+(meditations
+ "Macros are just function eval-ed at compile time"
+ (= "Hello, Macros!" (hello "Macros!"))
+ 
+ "Can I haz some infix?"
+ (= __ (infix (9 + 1)))
+ 
+ "Remember these are nothing but code transformations"
+ (= __ (macroexpand '(infix (9 + 1))))
+
+ "You can do better than that, hand crafting ftw"
+ (= __ (macroexpand '(infix-better (10 * 2))))
+ 
+ "Things dont always work as you would like them to... "
+ (= __ (macroexpand '(infix-better ( 10 + (2 * 3)))))
+
+ "Really, you dont understand recursion until you understand recursion"
+ (= __ (r-infix (10 + (2 * 3))))
+ 
+ )
+
diff --git a/src/path_to_answer_sheet.clj b/src/path_to_answer_sheet.clj
index 63844ad..3ea42e9 100644
--- a/src/path_to_answer_sheet.clj
+++ b/src/path_to_answer_sheet.clj
@@ -133,6 +133,16 @@
                  ]
            "___" ['(comp exclamator exclamator exclamator)
                   '(fn [x] (+ 20 x))]}
+
+      "macros" {"__" ['~(first form)
+                   '~(nth form 2)
+                   10
+                   ''(+ 9 1)
+                   ''(* 10 2)
+                   ''(+ 10 (2 * 3))
+                   16
+                   ]
+             }
    })
 
 (defn replace-with [s k replacements]
diff --git a/src/path_to_enlightenment.clj b/src/path_to_enlightenment.clj
index 9941bae..f70bf52 100644
--- a/src/path_to_enlightenment.clj
+++ b/src/path_to_enlightenment.clj
@@ -29,7 +29,8 @@
       "creating_functions"
       "recursion"
       "destructuring"
-      "refs"])
+      "refs"
+      "macros"])
 
 (defn require-version [[required-major required-minor]]
   (let [{:keys [major minor]} *clojure-version*]