Update function call stuff

src/lisp.c

@@ -75,14 +75,14 @@ static inline LispVal *lookup_variable(LispSymbol *name, LispVal *lexenv) {
     if (lexval != Qunbound) {
         return lexval;
     }
-    if (name->value == Qunbound) {
+    if (SYMBOL_VALUE(name) == Qunbound) {
         // TODO better error
         printf("Unbound symbol: ");
         debug_print(stdout, name);
         fputc('\n', stdout);
         abort();
     }
-    return name->value;
+    return SYMBOL_VALUE(name);
 }
 
 DEFUN(eval, "eval", (LispVal * form, LispVal *lexenv),
@@ -131,6 +131,7 @@ DEFSPECIAL(progn, "progn", (LispVal * forms), "(&rest forms)", "") {
 DEFSPECIAL(let, "let", (LispVal * bindings, LispVal *body),
            "(bindings &rest body)", "") {
     CHECK_LISTP(bindings);
+    StackFrame *stack_ref = LISP_STACK_REF();
     LispVal *lexenv = Vlexical_environment;
     DOLIST(binding, bindings) {
         if (SYMBOLP(binding)) {
@@ -145,7 +146,43 @@ DEFSPECIAL(let, "let", (LispVal * bindings, LispVal *body),
         }
     }
     push_dynamic_binding(Qlexical_environment, lexenv);
-    return Fprogn(body);
+    return UNWIND_AND_RETURN(stack_ref, Fprogn(body));
+}
+
+DEFSPECIAL(if, "if", (LispVal * cond, LispVal *then, LispVal *otherwise),
+           "(cond then &rest else)", "") {
+    StackFrame *stack_ref = LISP_STACK_REF();
+    LispVal *res = Feval(cond, Vlexical_environment);
+    if (!NILP(res)) {
+        return UNWIND_AND_RETURN(stack_ref, Feval(then, Vlexical_environment));
+    } else {
+        return UNWIND_AND_RETURN(stack_ref, Fprogn(otherwise));
+    }
+}
+
+DEFSPECIAL(and, "and", (LispVal * forms), "(&rest forms)", "") {
+    LispVal *res = Qt;
+    DOLIST(form, forms) {
+        res = Feval(form, Vlexical_environment);
+        if (NILP(res)) {
+            return Qnil;
+        }
+    }
+    return res;
+}
+
+DEFSPECIAL(or, "or", (LispVal * forms), "(&rest forms)", "") {
+    DOLIST(form, forms) {
+        LispVal *res = Feval(form, Vlexical_environment);
+        if (!NILP(res)) {
+            return res;
+        }
+    }
+    return Qnil;
+}
+
+DEFUN(null, "null", (LispVal * datum), "(datum)", "") {
+    return NILP(datum) ? Qt : Qnil;
 }
 
 void debug_print(FILE *file, LispVal *obj) {