From daa6443e7cec13167110a947076f0e8e90409526 Mon Sep 17 00:00:00 2001
From: "Paul R. Tagliamonte" <paultag@debian.org>
Date: Tue, 12 Mar 2013 22:04:51 -0400
Subject: [PATCH] Adding in a Threading macro (->)

---
 hy/core/bootstrap.py           | 12 ++++++++++++
 tests/native_tests/language.hy |  5 +++++
 2 files changed, 17 insertions(+)

diff --git a/hy/core/bootstrap.py b/hy/core/bootstrap.py
index 2e7dd3d..18f4cd5 100644
--- a/hy/core/bootstrap.py
+++ b/hy/core/bootstrap.py
@@ -45,3 +45,15 @@ def cond_macro(tree):
         ret = n
 
     return root
+
+
+@macro("_>")
+def threading_macro(tree):
+    tree.pop(0)  # ->
+    tree.reverse()
+    ret = tree.pop(0)
+    root = ret
+    for node in tree:
+        ret.insert(1, node)
+        ret = node
+    return root
diff --git a/tests/native_tests/language.hy b/tests/native_tests/language.hy
index 9c079f4..1d78333 100644
--- a/tests/native_tests/language.hy
+++ b/tests/native_tests/language.hy
@@ -131,3 +131,8 @@
   (def foo "3")
   (assert (= *foo* FOO))
   (assert (!= *foo* foo)))
+
+(defn test-threading []
+  "NATIVE: test threading macro"
+  (assert (= (-> (.upper "a b c d") (.replace "A" "X") (.split))
+             ["X" "B" "C" "D"])))