From e87f6323273e077d4453758511009be92c14c77c Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Thu, 17 Oct 2013 22:42:20 +0900
Subject: [PATCH] writer writes lists in short form

---
 include/picrin/value.h |  3 ++-
 src/gc.c               |  4 ++--
 src/port.c             | 23 ++++++++++++++++++++---
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/include/picrin/value.h b/include/picrin/value.h
index e752f36a..743e04dd 100644
--- a/include/picrin/value.h
+++ b/include/picrin/value.h
@@ -50,7 +50,7 @@ struct pic_symbol {
 
 struct pic_proc;
 
-#define pic_object_ptr(o) ((struct pic_object *)o.u.data)
+#define pic_obj_ptr(o) ((struct pic_object *)o.u.data)
 #define pic_pair_ptr(o) ((struct pic_pair *)o.u.data)
 #define pic_symbol_ptr(o) ((struct pic_symbol *)o.u.data)
 
@@ -70,5 +70,6 @@ pic_value pic_float_value(double);
 #define pic_true_p(v) ((v).type == PIC_VTYPE_TRUE)
 #define pic_false_p(v) ((v).type == PIC_VTYPE_FALSE)
 #define pic_undef_p(v) ((v).type == PIC_VTYPE_UNDEF)
+#define pic_pair_p(v) (pic_type(v) == PIC_TT_PAIR)
 
 #endif
diff --git a/src/gc.c b/src/gc.c
index 7902a92e..436fbcc6 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -78,7 +78,7 @@ pic_gc_protect(pic_state *pic, pic_value v)
   if (v.type != PIC_VTYPE_HEAP) {
     return;
   }
-  obj = pic_object_ptr(v);
+  obj = pic_obj_ptr(v);
 
   gc_protect(pic, obj);
 }
@@ -160,7 +160,7 @@ gc_mark(pic_state *pic, pic_value v)
 
   if (v.type != PIC_VTYPE_HEAP)
     return;
-  obj = pic_object_ptr(v);
+  obj = pic_obj_ptr(v);
 
   gc_mark_object(pic, obj);
 }
diff --git a/src/port.c b/src/port.c
index 457bd004..f4e5de2b 100644
--- a/src/port.c
+++ b/src/port.c
@@ -4,6 +4,8 @@
 #include "picrin.h"
 #include "picrin/proc.h"
 
+static void write_pair(pic_state *pic, struct pic_pair *pair);
+
 static void
 write(pic_state *pic, pic_value obj)
 {
@@ -19,9 +21,7 @@ write(pic_state *pic, pic_value obj)
     break;
   case PIC_TT_PAIR:
     printf("(");
-    write(pic, pic_car(pic, obj));
-    printf(" . ");
-    write(pic, pic_cdr(pic, obj));
+    write_pair(pic, pic_pair_ptr(obj));
     printf(")");
     break;
   case PIC_TT_SYMBOL:
@@ -39,6 +39,23 @@ write(pic_state *pic, pic_value obj)
   }
 }
 
+static void
+write_pair(pic_state *pic, struct pic_pair *pair)
+{
+  write(pic, pair->car);
+
+  if (pic_nil_p(pair->cdr)) {
+    return;
+  }
+  if (pic_pair_p(pair->cdr)) {
+    printf(" ");
+    write_pair(pic, pic_pair_ptr(pair->cdr));
+    return;
+  }
+  printf(" . ");
+  write(pic, pair->cdr);
+}
+
 void
 pic_debug(pic_state *pic, pic_value obj)
 {