X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=src%2Flisp%2Fao_lisp_eval.c;h=a5c742503f89452271a5dfb2c3124d63659ff212;hb=6e5c1308ce33a864095eae02e7db18b0e043ab6e;hp=6eef1f23d148f08c1b5ac4c094be412b472ef209;hpb=11cb03b1d336ee90c422be27588f57be573a9546;p=fw%2Faltos

diff --git a/src/lisp/ao_lisp_eval.c b/src/lisp/ao_lisp_eval.c
index 6eef1f23..a5c74250 100644
--- a/src/lisp/ao_lisp_eval.c
+++ b/src/lisp/ao_lisp_eval.c
@@ -14,188 +14,496 @@
 
 #include "ao_lisp.h"
 
-/*
- * Non-recursive eval
- *
- * Plan: walk actuals, construct formals
- *
- * stack >  save  > actuals > actual_1
- *           v         v
- *	   formals     .    > actual_2
- */
-
-static struct ao_lisp_cons	*stack;
-static struct ao_lisp_cons	*actuals;
-static struct ao_lisp_cons	*formals;
-static struct ao_lisp_cons	*formals_tail;
-static uint8_t been_here;
-
 #if 0
-#define DBG(...) printf(__VA_ARGS__)
-#define DBG_CONS(a)	ao_lisp_cons_print(a)
+#define DBG_CODE	1
+static int stack_depth;
+#define DBG_INDENT()	do { int _s; for(_s = 0; _s < stack_depth; _s++) printf("  "); } while(0)
+#define DBG_IN()	(++stack_depth)
+#define DBG_OUT()	(--stack_depth)
+#define DBG(...) 	printf(__VA_ARGS__)
+#define DBGI(...)	do { DBG_INDENT(); DBG("%4d: ", __LINE__); DBG(__VA_ARGS__); } while (0)
+#define DBG_CONS(a)	ao_lisp_cons_print(ao_lisp_cons_poly(a))
 #define DBG_POLY(a)	ao_lisp_poly_print(a)
+#define OFFSET(a)	((a) ? (int) ((uint8_t *) a - ao_lisp_pool) : -1)
 #else
+#define DBG_INDENT()
+#define DBG_IN()
+#define DBG_OUT()
 #define DBG(...)
+#define DBGI(...)
 #define DBG_CONS(a)
 #define DBG_POLY(a)
 #endif
 
+enum eval_state {
+	eval_sexpr,
+	eval_val,
+	eval_formal,
+	eval_exec,
+	eval_exec_direct,
+	eval_cond,
+	eval_cond_test
+};
+
+struct ao_lisp_stack {
+	ao_poly			prev;
+	uint8_t			state;
+	uint8_t			macro;
+	ao_poly			actuals;
+	ao_poly			formals;
+	ao_poly			formals_tail;
+	ao_poly			frame;
+};
+
+static struct ao_lisp_stack *
+ao_lisp_poly_stack(ao_poly p)
+{
+	return ao_lisp_ref(p);
+}
+
+static ao_poly
+ao_lisp_stack_poly(struct ao_lisp_stack *stack)
+{
+	return ao_lisp_poly(stack, AO_LISP_OTHER);
+}
+
+static int
+stack_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_stack);
+}
+
+static void
+stack_mark(void *addr)
+{
+	struct ao_lisp_stack	*stack = addr;
+	for (;;) {
+		ao_lisp_poly_mark(stack->actuals, 0);
+		ao_lisp_poly_mark(stack->formals, 0);
+		/* no need to mark formals_tail */
+		ao_lisp_poly_mark(stack->frame, 0);
+		stack = ao_lisp_poly_stack(stack->prev);
+		if (ao_lisp_mark_memory(stack, sizeof (struct ao_lisp_stack)))
+			break;
+	}
+}
+
+static const struct ao_lisp_type ao_lisp_stack_type;
+
+#if DBG_CODE
+static void
+stack_validate_tail(struct ao_lisp_stack *stack)
+{
+	struct ao_lisp_cons *head = ao_lisp_poly_cons(stack->formals);
+	struct ao_lisp_cons *tail = ao_lisp_poly_cons(stack->formals_tail);
+	struct ao_lisp_cons *cons;
+	for (cons = head; cons && cons->cdr && cons != tail; cons = ao_lisp_poly_cons(cons->cdr))
+		;
+	if (cons != tail || (tail && tail->cdr)) {
+		if (!tail) {
+			printf("tail null\n");
+		} else {
+			printf("tail validate fail head %d actual %d recorded %d\n",
+			       OFFSET(head), OFFSET(cons), OFFSET(tail));
+			abort();
+		}
+	}
+}
+#else
+#define stack_validate_tail(s)
+#endif
+
+static void
+stack_move(void *addr)
+{
+	struct ao_lisp_stack	*stack = addr;
+
+	while (stack) {
+		void	*prev;
+		int	ret;
+		(void) ao_lisp_poly_move(&stack->actuals, 0);
+		(void) ao_lisp_poly_move(&stack->formals, 0);
+		(void) ao_lisp_poly_move(&stack->formals_tail, 0);
+		(void) ao_lisp_poly_move(&stack->frame, 0);
+		prev = ao_lisp_poly_stack(stack->prev);
+		ret = ao_lisp_move(&ao_lisp_stack_type, &prev);
+		if (prev != ao_lisp_poly_stack(stack->prev))
+			stack->prev = ao_lisp_stack_poly(prev);
+		stack_validate_tail(stack);
+		if (ret)
+			break;
+		stack = ao_lisp_poly_stack(stack->prev);
+	}
+}
+
+static const struct ao_lisp_type ao_lisp_stack_type = {
+	.size = stack_size,
+	.mark = stack_mark,
+	.move = stack_move
+};
+
+static struct ao_lisp_stack	*ao_lisp_stack;
+static ao_poly			ao_lisp_v;
+static uint8_t been_here;
+
+#if DBG_CODE
+static void
+stack_validate_tails(void)
+{
+	struct ao_lisp_stack	*stack;
+
+	for (stack = ao_lisp_stack; stack; stack = ao_lisp_poly_stack(stack->prev))
+		stack_validate_tail(stack);
+}
+#else
+#define stack_validate_tails(s)
+#endif
+
 ao_poly
-ao_lisp_eval(ao_poly v)
+ao_lisp_set_cond(struct ao_lisp_cons *c)
 {
-	struct ao_lisp_cons	*formal;
-	int			cons = 0;
+	ao_lisp_stack->state = eval_cond;
+	ao_lisp_stack->actuals = ao_lisp_cons_poly(c);
+	return AO_LISP_NIL;
+}
 
-	if (!been_here) {
-		been_here = 1;
-		ao_lisp_root_add(&ao_lisp_cons_type, &stack);
-		ao_lisp_root_add(&ao_lisp_cons_type, &actuals);
-		ao_lisp_root_add(&ao_lisp_cons_type, &formals);
-		ao_lisp_root_add(&ao_lisp_cons_type, &formals_tail);
+void
+ao_lisp_stack_reset(struct ao_lisp_stack *stack)
+{
+	stack->state = eval_sexpr;
+	stack->macro = 0;
+	stack->actuals = AO_LISP_NIL;
+	stack->formals = AO_LISP_NIL;
+	stack->formals_tail = AO_LISP_NIL;
+	stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
+	stack_validate_tails();
+}
+
+int
+ao_lisp_stack_push(void)
+{
+	stack_validate_tails();
+	if (ao_lisp_stack) {
+		DBGI("formals "); DBG_POLY(ao_lisp_stack->formals); DBG("\n");
+		DBGI("actuals "); DBG_POLY(ao_lisp_stack->actuals); DBG("\n");
 	}
-	stack = 0;
-	actuals = 0;
-	formals = 0;
-	formals_tail = 0;
-	for (;;) {
+	DBGI("stack push\n");
+	DBG_IN();
+	struct ao_lisp_stack	*stack = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
+	if (!stack)
+		return 0;
+	stack->prev = ao_lisp_stack_poly(ao_lisp_stack);
+	ao_lisp_stack = stack;
+	ao_lisp_stack_reset(stack);
+	stack_validate_tails();
+	return 1;
+}
 
-	restart:
-		/* Build stack frames for each list */
-		while (ao_lisp_poly_type(v) == AO_LISP_CONS) {
-			if (v == AO_LISP_NIL)
-				break;
+void
+ao_lisp_stack_pop(void)
+{
+	if (!ao_lisp_stack)
+		return;
+	stack_validate_tails();
+	DBG_OUT();
+	DBGI("stack pop\n");
+	ao_lisp_stack = ao_lisp_poly_stack(ao_lisp_stack->prev);
+	if (ao_lisp_stack)
+		ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->frame);
+	else
+		ao_lisp_frame_current = NULL;
+	if (ao_lisp_stack) {
+		DBGI("formals "); DBG_POLY(ao_lisp_stack->formals); DBG("\n");
+		DBGI("actuals "); DBG_POLY(ao_lisp_stack->actuals); DBG("\n");
+	}
+}
+
+static void
+ao_lisp_stack_clear(void)
+{
+	stack_validate_tails();
+	ao_lisp_stack = NULL;
+	ao_lisp_frame_current = NULL;
+}
 
-			/* Push existing frame on the stack */
-			if (cons++) {
-				struct ao_lisp_cons *frame;
+static ao_poly
+func_type(ao_poly func)
+{
+	struct ao_lisp_cons	*cons;
+	struct ao_lisp_cons	*args;
+	int			f;
 
-				frame = ao_lisp_cons_cons(ao_lisp_cons_poly(actuals), formals);
-				stack = ao_lisp_cons_cons(ao_lisp_cons_poly(frame), stack);
+	DBGI("func type "); DBG_POLY(func); DBG("\n");
+	if (func == AO_LISP_NIL)
+		return ao_lisp_error(AO_LISP_INVALID, "func is nil");
+	if (ao_lisp_poly_type(func) == AO_LISP_BUILTIN) {
+		struct ao_lisp_builtin *b = ao_lisp_poly_builtin(func);
+		return b->args;
+	} else if (ao_lisp_poly_type(func) == AO_LISP_CONS) {
+		cons = ao_lisp_poly_cons(func);
+		if (!ao_lisp_check_argc(_ao_lisp_atom_lambda, cons, 3, 3))
+			return AO_LISP_NIL;
+		if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, cons, 0, AO_LISP_ATOM, 0))
+			return AO_LISP_NIL;
+		if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, cons, 1, AO_LISP_CONS, 1))
+			return AO_LISP_NIL;
+		args = ao_lisp_poly_cons(ao_lisp_arg(cons, 1));
+		f = 0;
+		while (args) {
+			if (ao_lisp_poly_type(args->car) != AO_LISP_ATOM) {
+				return ao_lisp_error(ao_lisp_arg(cons, 0), "formal %d is not an atom", f);
 			}
-			actuals = ao_lisp_poly_cons(v);
-			formals = NULL;
-			formals_tail = NULL;
-			v = actuals->car;
-
-			DBG("start: stack"); DBG_CONS(stack); DBG("\n");
-			DBG("start: actuals"); DBG_CONS(actuals); DBG("\n");
-			DBG("start: formals"); DBG_CONS(formals); DBG("\n");
+			args = ao_lisp_poly_cons(args->cdr);
+			f++;
 		}
+		return ao_lisp_arg(cons, 0);
+	} else {
+		ao_lisp_error(AO_LISP_INVALID, "not a func");
+		abort();
+		return AO_LISP_NIL;
+	}
+}
 
-		/* Evaluate primitive types */
+static int
+ao_lisp_cons_length(struct ao_lisp_cons *cons)
+{
+	int	len = 0;
+	while (cons) {
+		len++;
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	return len;
+}
 
-		DBG ("actual: "); DBG_POLY(v); DBG("\n");
+static ao_poly
+ao_lisp_lambda(struct ao_lisp_cons *cons)
+{
+	ao_poly			type;
+	struct ao_lisp_cons	*lambda;
+	struct ao_lisp_cons	*args;
+	struct ao_lisp_frame	*next_frame;
+	int			args_wanted;
+	int			args_provided;
 
-		switch (ao_lisp_poly_type(v)) {
-		case AO_LISP_INT:
-		case AO_LISP_STRING:
-			break;
-		case AO_LISP_ATOM:
-			v = ao_lisp_atom_get(v);
-			break;
+	lambda = ao_lisp_poly_cons(ao_lisp_arg(cons, 0));
+	DBGI("lambda "); DBG_CONS(lambda); DBG("\n");
+	type = ao_lisp_arg(lambda, 0);
+	args = ao_lisp_poly_cons(ao_lisp_arg(lambda, 1));
+
+	args_wanted = ao_lisp_cons_length(args);
+
+	/* Create a frame to hold the variables
+	 */
+	if (type == _ao_lisp_atom_lambda)
+		args_provided = ao_lisp_cons_length(cons) - 1;
+	else
+		args_provided = 1;
+	if (args_wanted != args_provided)
+		return ao_lisp_error(AO_LISP_INVALID, "need %d args, not %d", args_wanted, args_provided);
+	next_frame = ao_lisp_frame_new(args_wanted);
+//	DBGI("new frame %d\n", OFFSET(next_frame));
+	switch (type) {
+	case _ao_lisp_atom_lambda: {
+		int			f;
+		struct ao_lisp_cons	*vals = ao_lisp_poly_cons(cons->cdr);
+
+		for (f = 0; f < args_wanted; f++) {
+			next_frame->vals[f].atom = args->car;
+			next_frame->vals[f].val = vals->car;
+			args = ao_lisp_poly_cons(args->cdr);
+			vals = ao_lisp_poly_cons(vals->cdr);
 		}
+		break;
+	}
+	case _ao_lisp_atom_lexpr:
+	case _ao_lisp_atom_nlambda:
+		next_frame->vals[0].atom = args->car;
+		next_frame->vals[0].val = cons->cdr;
+		break;
+	case _ao_lisp_atom_macro:
+		next_frame->vals[0].atom = args->car;
+		next_frame->vals[0].val = ao_lisp_cons_poly(cons);
+		break;
+	}
+	next_frame->next = ao_lisp_frame_poly(ao_lisp_frame_current);
+	ao_lisp_frame_current = next_frame;
+	ao_lisp_stack->frame = ao_lisp_frame_poly(next_frame);
+	return ao_lisp_arg(lambda, 2);
+}
+
+ao_poly
+ao_lisp_eval(ao_poly _v)
+{
+	ao_poly			formal;
+
+	ao_lisp_v = _v;
+	if (!been_here) {
+		been_here = 1;
+		ao_lisp_root_add(&ao_lisp_stack_type, &ao_lisp_stack);
+		ao_lisp_root_poly_add(&ao_lisp_v);
+	}
+
+	if (!ao_lisp_stack_push())
+		goto bail;
 
-		if (!cons)
+	for (;;) {
+		if (ao_lisp_exception)
+			goto bail;
+		switch (ao_lisp_stack->state) {
+		case eval_sexpr:
+			DBGI("sexpr: "); DBG_POLY(ao_lisp_v); DBG("\n");
+			switch (ao_lisp_poly_type(ao_lisp_v)) {
+			case AO_LISP_CONS:
+				if (ao_lisp_v == AO_LISP_NIL) {
+					ao_lisp_stack->state = eval_exec;
+					break;
+				}
+				ao_lisp_stack->actuals = ao_lisp_v;
+				DBGI("actuals now "); DBG_POLY(ao_lisp_v); DBG("\n");
+				ao_lisp_stack->state = eval_formal;
+				if (!ao_lisp_stack_push())
+					goto bail;
+				ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
+				stack_validate_tails();
+				break;
+			case AO_LISP_ATOM:
+				ao_lisp_v = ao_lisp_atom_get(ao_lisp_v);
+				/* fall through */
+			case AO_LISP_INT:
+			case AO_LISP_STRING:
+			case AO_LISP_BUILTIN:
+				ao_lisp_stack->state = eval_val;
+				break;
+			}
+			break;
+		case eval_val:
+			DBGI("val: "); DBG_POLY(ao_lisp_v); DBG("\n");
+			ao_lisp_stack_pop();
+			if (!ao_lisp_stack)
+				return ao_lisp_v;
+			DBGI("..state %d\n", ao_lisp_stack->state);
 			break;
 
-		for (;;) {
-			DBG("add formal: "); DBG_POLY(v); DBG("\n");
-
-			if (formals == NULL) {
-				if (ao_lisp_poly_type(v) == AO_LISP_BUILTIN) {
-					struct ao_lisp_builtin *b = ao_lisp_poly_builtin(v);
-					switch (b->args) {
-					case AO_LISP_NLAMBDA:
-						v = ao_lisp_func(b)(ao_lisp_poly_cons(actuals->cdr));
-						goto done_eval;
-
-					case AO_LISP_MACRO:
-						v = ao_lisp_func(b)(ao_lisp_poly_cons(actuals->cdr));
-						DBG("macro "); DBG_POLY(ao_lisp_cons_poly(actuals));
-						DBG(" -> "); DBG_POLY(v);
-						DBG("\n");
-						if (ao_lisp_poly_type(v) != AO_LISP_CONS) {
-							ao_lisp_exception |= AO_LISP_INVALID;
-							return AO_LISP_NIL;
-						}
-
-						/* Reset frame to the new list */
-						actuals = ao_lisp_poly_cons(v);
-						v = actuals->car;
-						goto restart;
-					}
+		case eval_formal:
+			/* Check what kind of function we've got */
+			if (!ao_lisp_stack->formals) {
+				switch (func_type(ao_lisp_v)) {
+				case AO_LISP_LAMBDA:
+				case _ao_lisp_atom_lambda:
+				case AO_LISP_LEXPR:
+				case _ao_lisp_atom_lexpr:
+					DBGI(".. lambda or lexpr\n");
+					break;
+				case AO_LISP_MACRO:
+				case _ao_lisp_atom_macro:
+					ao_lisp_stack->macro = 1;
+				case AO_LISP_NLAMBDA:
+				case _ao_lisp_atom_nlambda:
+					DBGI(".. nlambda or macro\n");
+					ao_lisp_stack->formals = ao_lisp_stack->actuals;
+					ao_lisp_stack->formals_tail = AO_LISP_NIL;
+					ao_lisp_stack->state = eval_exec_direct;
+					stack_validate_tails();
+					break;
 				}
+				if (ao_lisp_stack->state == eval_exec_direct)
+					break;
 			}
 
-			formal = ao_lisp_cons_cons(v, NULL);
-			if (formals_tail)
-				formals_tail->cdr = ao_lisp_cons_poly(formal);
+			DBGI("add formal "); DBG_POLY(ao_lisp_v); DBG("\n");
+			stack_validate_tails();
+			formal = ao_lisp_cons_poly(ao_lisp_cons_cons(ao_lisp_v, NULL));
+			stack_validate_tails();
+			if (!formal)
+				goto bail;
+
+			if (ao_lisp_stack->formals_tail)
+				ao_lisp_poly_cons(ao_lisp_stack->formals_tail)->cdr = formal;
 			else
-				formals = formal;
-			formals_tail = formal;
-			actuals = ao_lisp_poly_cons(actuals->cdr);
-
-			DBG("formals: ");
-			DBG_CONS(formals);
-			DBG("\n");
-			DBG("actuals: ");
-			DBG_CONS(actuals);
-			DBG("\n");
-
-			/* Process all of the arguments */
-			if (actuals) {
-				v = actuals->car;
-				break;
-			}
+				ao_lisp_stack->formals = formal;
+			ao_lisp_stack->formals_tail = formal;
 
-			v = formals->car;
+			DBGI("formals now "); DBG_POLY(ao_lisp_stack->formals); DBG("\n");
 
-			/* Evaluate the resulting list */
-			if (ao_lisp_poly_type(v) == AO_LISP_BUILTIN) {
-				struct ao_lisp_builtin *b = ao_lisp_poly_builtin(v);
+			ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->actuals)->cdr;
 
-				v = ao_lisp_func(b) (ao_lisp_poly_cons(formals->cdr));
+			stack_validate_tails();
+			ao_lisp_stack->state = eval_sexpr;
 
-				DBG ("eval: ");
-				DBG_CONS(formals);
-				DBG(" -> ");
-				DBG_POLY(v);
-				DBG ("\n");
+			break;
+		case eval_exec:
+			if (!ao_lisp_stack->formals) {
+				ao_lisp_v = AO_LISP_NIL;
+				ao_lisp_stack->state = eval_val;
+				break;
+			}
+			ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->formals)->car;
+		case eval_exec_direct:
+			DBGI("exec: macro %d ", ao_lisp_stack->macro); DBG_POLY(ao_lisp_v); DBG(" formals "); DBG_POLY(ao_lisp_stack->formals); DBG ("\n");
+			if (ao_lisp_poly_type(ao_lisp_v) == AO_LISP_BUILTIN) {
+				stack_validate_tails();
+				struct ao_lisp_builtin	*b = ao_lisp_poly_builtin(ao_lisp_v);
+				stack_validate_tails();
+				struct ao_lisp_cons	*f = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->formals)->cdr);
+
+				DBGI(".. builtin formals "); DBG_CONS(f); DBG("\n");
+				stack_validate_tails();
+				if (ao_lisp_stack->macro)
+					ao_lisp_stack->state = eval_sexpr;
+				else
+					ao_lisp_stack->state = eval_val;
+				ao_lisp_stack->macro = 0;
+				ao_lisp_stack->actuals = ao_lisp_stack->formals = ao_lisp_stack->formals_tail = AO_LISP_NIL;
+				ao_lisp_v = ao_lisp_func(b) (f);
+				DBGI("builtin result:"); DBG_POLY(ao_lisp_v); DBG ("\n");
+				if (ao_lisp_exception)
+					goto bail;
+				break;
 			} else {
-				ao_lisp_exception |= AO_LISP_INVALID;
+				ao_lisp_v = ao_lisp_lambda(ao_lisp_poly_cons(ao_lisp_stack->formals));
+				ao_lisp_stack_reset(ao_lisp_stack);
 			}
-			if (ao_lisp_exception)
-				return AO_LISP_NIL;
-		done_eval:
-			if (--cons) {
-				struct ao_lisp_cons	*frame;
-
-				/* Pop the previous frame off the stack */
-				frame = ao_lisp_poly_cons(stack->car);
-				actuals = ao_lisp_poly_cons(frame->car);
-				formals = ao_lisp_poly_cons(frame->cdr);
-				formals_tail = NULL;
-
-				/* Recompute the tail of the formals list */
-				if (formals) {
-					for (formal = formals; formal->cdr != AO_LISP_NIL; formal = ao_lisp_poly_cons(formal->cdr));
-					formals_tail = formal;
+			break;
+		case eval_cond:
+			DBGI("cond: "); DBG_POLY(ao_lisp_stack->actuals); DBG("\n");
+			if (!ao_lisp_stack->actuals) {
+				ao_lisp_v = AO_LISP_NIL;
+				ao_lisp_stack->state = eval_val;
+			} else {
+				ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->actuals)->car;
+				if (!ao_lisp_v || ao_lisp_poly_type(ao_lisp_v) != AO_LISP_CONS) {
+					ao_lisp_error(AO_LISP_INVALID, "invalid cond clause");
+					goto bail;
+				}
+				ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
+				ao_lisp_stack->state = eval_cond_test;
+				stack_validate_tails();
+				ao_lisp_stack_push();
+				stack_validate_tails();
+				ao_lisp_stack->state = eval_sexpr;
+			}
+			break;
+		case eval_cond_test:
+			DBGI("cond_test: "); DBG_POLY(ao_lisp_v); DBG(" actuals "); DBG_POLY(ao_lisp_stack->actuals); DBG("\n");
+			if (ao_lisp_v) {
+				struct ao_lisp_cons *car = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->actuals)->car);
+				struct ao_lisp_cons *c = ao_lisp_poly_cons(car->cdr);
+				if (c) {
+					ao_lisp_v = c->car;
+					ao_lisp_stack->state = eval_sexpr;
+				} else {
+					ao_lisp_stack->state = eval_val;
 				}
-
-				stack = ao_lisp_poly_cons(stack->cdr);
-				DBG("stack pop: stack"); DBG_CONS(stack); DBG("\n");
-				DBG("stack pop: actuals"); DBG_CONS(actuals); DBG("\n");
-				DBG("stack pop: formals"); DBG_CONS(formals); DBG("\n");
 			} else {
-				actuals = 0;
-				formals = 0;
-				formals_tail = 0;
-				DBG("done func\n");
-				break;
+				ao_lisp_stack->actuals = ao_lisp_poly_cons(ao_lisp_stack->actuals)->cdr;
+				DBGI("actuals now "); DBG_POLY(ao_lisp_stack->actuals); DBG("\n");
+				ao_lisp_stack->state = eval_cond;
 			}
-		}
-		if (!cons)
 			break;
+		}
 	}
-	return v;
+bail:
+	ao_lisp_stack_clear();
+	return AO_LISP_NIL;
 }