first evaluator draft

wscm.h

@@ -2,6 +2,8 @@
 #include <stdint.h>
 
 // common types
+typedef void V;
+
 typedef uintptr_t U;
 typedef intptr_t I;
 
@@ -16,7 +18,13 @@ typedef uintptr_t O;
 // cons pair
 typedef struct C C;
 struct C {
-  O head, tail;
+  O car, cdr;
+};
+
+// lambda
+typedef struct L L;
+struct L {
+  O args, body, env;
 };
 
 // symbol
@@ -35,9 +43,32 @@ struct St {
   S **data;
 };
 
-// gc header
-enum { OBJ_CONS, OBJ_SYM, OBJ_FWD };
+#define TYPE_MASK 7
 
+enum {
+  TAG_GC = 0,   // GC-managed object
+  TAG_NUM = 1,  // Immediate number
+  TAG_SYM = 2,  // Pointer to symbol
+  TAG_PRIM = 4, // Pointer to primitive
+};
+
+enum {
+  KIND_NIL = 0,
+  KIND_NUM = 1,
+  KIND_SYM = 2,
+  KIND_PRIM = 4,
+  KIND_CONS = 5,
+  KIND_CLOS = 6,
+  KIND__MAX,
+};
+
+#define TYPE(x) (((U)(x)) & TYPE_MASK)
+#define UNTAG(x) (((U)(x)) & ~TYPE_MASK)
+#define TAG(x, t) (void *)(((U)(x)) | t)
+
+enum { OBJ_CONS = 5, OBJ_CLOS = 6, OBJ_FWD = 7 };
+
+// gc header
 typedef struct H H;
 struct H {
   I type;
@@ -57,15 +88,28 @@ struct E {
   O **roots;
 };
 
+// primitive
+typedef struct P P;
+struct P {
+  const char *name;
+  O (*fn)(O, O);
+};
+
 extern E heap;
 extern St syms;
 
+#define ALIGN(n) (((n) + 7) & ~7)
+#define INFROM(x)                                                              \
+  (((const U8 *)x) >= heap.from.start && ((const U8 *)x) < heap.from.end)
+
 #define IMM(x) ((x) & 1)
-#define NUM(x) (((O)((I)(x) << 1)) | (V)1)
+#define NUM(x) (((O)((I)(x) << 1)) | (O)1)
 #define ORD(x) ((I)(x) >> 1)
 #define BOX(x) ((O)(x))
 #define UNBOX(x) ((H *)(x))
 
+#define SYM(s) BOX(TAG(intern(s, -1), TAG_SYM))
+
 #define NIL ((O)0)
 #define GC_HEAP_BYTES (1024 * 1024)
 
@@ -78,11 +122,17 @@ H *alloc(Z sz);
 void gcinit(void);
 void gcfinalize(void);
 
+I kind(O obj);
+const char *kindname(I k);
+
 S *intern(const char *str, I len);
 O mksym(const char *str);
 
 O cons(O head, O tail);
 C *uncons(O obj);
 
+V setupenv(O *env);
+O eval(O obj, O env);
+
 void print(O obj);
 void println(O obj);