From 9038939bd1233a47e7691e0c4b259bb68a31622c Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Thu, 10 Oct 2013 17:06:26 +0900
Subject: [PATCH] add some pair functions

---
 include/picrin.h |  4 ++++
 src/pair.c       | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 src/pair.c

diff --git a/include/picrin.h b/include/picrin.h
index 047dea57..6dcc8afe 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -13,4 +13,8 @@ void pic_free(pic_state *, void *);
 pic_state *pic_open();
 void pic_close(pic_state *);
 
+pic_value pic_cons(pic_state *pic, pic_value, pic_value);
+pic_value pic_car(pic_state *pic, pic_value);
+pic_value pic_cdr(pic_state *pic, pic_value);
+
 #endif
diff --git a/src/pair.c b/src/pair.c
new file mode 100644
index 00000000..3b4c4ad2
--- /dev/null
+++ b/src/pair.c
@@ -0,0 +1,33 @@
+#include "picrin.h"
+
+pic_value
+pic_cons(pic_state *pic, pic_value car, pic_value cdr)
+{
+  struct pic_pair *pair;
+
+  pair = (struct pic_pair *)pic_gc_alloc(pic, sizeof(struct pic_pair), PIC_TT_PAIR);
+  pair->car = car;
+  pair->cdr = cdr;
+
+  return pic_obj_value(pair);
+}
+
+pic_value
+pic_car(pic_state *pic, pic_value obj)
+{
+  struct pic_pair *pair;
+
+  pair = (struct pic_pair *)obj->u->data;
+
+  return pair->car;
+}
+
+pic_value
+pic_cdr(pic_state *pic, pic_value obj)
+{
+  struct pic_pair *pair;
+
+  pair = (struct pic_pair *)obj->u->data;
+
+  return pair->cdr;
+}