From d67676c7a607a64266f90fc6db6e2d83abd9147c Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Wed, 22 Jul 2015 23:01:35 -0400
Subject: [PATCH] Working on type validation for apply

---
 include/cyclone/types.h |  3 ++-
 runtime.c               | 35 ++++++++++++++++++++++++++++++++---
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index a76b9971..434b275c 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -55,7 +55,8 @@ typedef long tag_type;
 #define check_overflow(x,y) ((x) > (y))
 #endif
 
-/* Define tag values. Could be an enum... */
+/* Define tag values. Could be an enum...
+   Remember to update tag_names in runtime.c when adding new tags */
 #define cons_tag 0
 #define symbol_tag 1
 #define forward_tag 2
diff --git a/runtime.c b/runtime.c
index 94b6cc58..57106ca1 100644
--- a/runtime.c
+++ b/runtime.c
@@ -9,7 +9,29 @@
 #include "cyclone/types.h"
 #include "cyclone/runtime.h"
 
-/* TODO: working on validation for applying functions */
+const char *tag_names[20] = { \
+   "pair" \
+ , "symbol" \
+ , "" \
+ , "closure" \
+ , "closure" \
+ , "closure" \
+ , "closure" \
+ , "closure" \
+ , "closure" \
+ , "integer" \
+ , "double" \
+ , "string" \
+ , "primitive" \
+ , "eof" \
+ , "port" \
+ , "boolean" \
+ , "C primitive" \
+ , "vector" \
+ , "" \
+ , "" };
+
+/* Error handling section */
 #define Cyc_check_num_args(fnc_name, num_args, args) { \
   integer_type l = Cyc_length(args); \
   if (num_args > l.value) { \
@@ -19,6 +41,12 @@
   } \
 }
 
+void Cyc_invalid_type_error(int tag, object found) {
+  char buf[256];
+  snprintf(buf, 255, "Invalid type: expected %s, found", tag_names[tag]);
+  Cyc_rt_raise2(buf, found);
+}
+
 /* Funcall section, these are hardcoded here to support
    functions in this module. */
 #define funcall1(cfn,a1) if (type_of(cfn) == cons_tag || prim(cfn)) { Cyc_apply(0, (closure)a1, cfn); } else { ((cfn)->fn)(1,cfn,a1);}
@@ -1231,8 +1259,9 @@ void _Cyc_91global_91vars(object cont, object args){
     return_funcall1(cont, Cyc_global_variables); } 
 void _car(object cont, object args) { 
     Cyc_check_num_args("car", 1, args);
-    //Cyc_check_type("car", 
-    return_funcall1(cont, car(car(args))); }
+    { object var = car(args);
+      if (eq(boolean_f, Cyc_is_cons(var))) Cyc_invalid_type_error(cons_tag, var);
+      return_funcall1(cont, car(var)); }}
 void _cdr(object cont, object args) { 
     Cyc_check_num_args("cdr", 1, args);
     return_funcall1(cont, cdr(car(args))); }