1 files changed, 40 insertions, 17 deletions

diff --git a/src/bootstrap/primitives.c b/src/bootstrap/primitives.c
index 6300067..806656e 100644
--- a/src/bootstrap/primitives.c
+++ b/src/bootstrap/primitives.c
@@ -300,49 +300,72 @@ proc_print(Object *args) {
 
 Object *
 proc_is_boolean(Object *args) {
-    Object *obj = NULL;
-    if (args->type == OBJ_TYPE_PAIR) {
-        obj = eval(args->car);
-    } else {
-        obj = eval(args);
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
     }
+    Object *obj = eval(args->car);
     return (obj == obj_true || obj == obj_false) ? obj_true : obj_false;
 }
 
 Object *
 proc_is_null(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj == obj_nil ? obj_true : obj_false;
 }
 
 Object *
 proc_is_symbol(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj->type == OBJ_TYPE_SYMBOL ? obj_true : obj_false;
 }
 
 Object *
 proc_is_string(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj->type == OBJ_TYPE_STRING ? obj_true : obj_false;
 }
 
 Object *
 proc_is_fixnum(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj->type == OBJ_TYPE_FIXNUM ? obj_true : obj_false;
 }
 
 Object *
 proc_is_pair(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj->type == OBJ_TYPE_PAIR ? obj_true : obj_false;
 }
 
 Object *
 proc_is_procedure(Object *args) {
-    // TODO: stub
-    return NULL;
+    if (args->type != OBJ_TYPE_PAIR) {
+        fprintf(stderr, "error: wrong number of arguments.\n");
+        return NULL;
+    }
+    Object *obj = eval(args->car);
+    return obj->type == OBJ_TYPE_PROCEDURE ? obj_true : obj_false;
 }
 
 //