altos/lisp: Make lambda, cond and while all have implicit progns

This lets all of these execute more than one sexpr, returning the
value of the last.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 29 insertions, 19 deletions

diff --git a/src/lisp/ao_lisp_eval.c b/src/lisp/ao_lisp_eval.c
index 6f56a120..5fa9e0ad 100644
--- a/src/lisp/ao_lisp_eval.c
+++ b/src/lisp/ao_lisp_eval.c
@@ -310,7 +310,6 @@ ao_lisp_eval_formal(void)
 			 * value and re-evaluate it
 			 */
 			prev = ao_lisp_poly_stack(ao_lisp_stack->prev);
-			ao_lisp_stack->state = eval_sexpr;
 			ao_lisp_stack->sexprs = prev->sexprs;
 
 			DBGI(".. start macro\n");
@@ -401,10 +400,11 @@ ao_lisp_eval_exec(void)
 		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
 		break;
 	case AO_LISP_LAMBDA:
-		ao_lisp_stack->state = eval_sexpr;
 		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
-		ao_lisp_v = ao_lisp_lambda_eval();
-		DBGI(".. sexpr "); DBG_POLY(ao_lisp_v); DBG("\n");
+		ao_lisp_stack->state = eval_progn;
+		v = ao_lisp_lambda_eval();
+		ao_lisp_stack->sexprs = v;
+		DBGI(".. sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
 		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
 		break;
 	}
@@ -442,7 +442,6 @@ ao_lisp_eval_cond(void)
 		ao_lisp_stack->state = eval_cond_test;
 		if (!ao_lisp_stack_push())
 			return 0;
-		ao_lisp_stack->state = eval_sexpr;
 	}
 	return 1;
 }
@@ -464,11 +463,11 @@ ao_lisp_eval_cond_test(void)
 	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
 	if (ao_lisp_v) {
 		struct ao_lisp_cons *car = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car);
-		struct ao_lisp_cons *c = ao_lisp_poly_cons(car->cdr);
+		ao_poly c = car->cdr;
 
 		if (c) {
-			ao_lisp_stack->state = eval_sexpr;
-			ao_lisp_v = c->car;
+			ao_lisp_stack->state = eval_progn;
+			ao_lisp_stack->sexprs = c;
 		} else
 			ao_lisp_stack->state = eval_val;
 	} else {
@@ -502,6 +501,10 @@ ao_lisp_eval_progn(void)
 	} else {
 		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
 		ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+
+		/* If there are more sexprs to do, then come back here, otherwise
+		 * return the value of the last one by just landing in eval_sexpr
+		 */
 		if (ao_lisp_stack->sexprs) {
 			ao_lisp_stack->state = eval_progn;
 			if (!ao_lisp_stack_push())
@@ -530,7 +533,6 @@ ao_lisp_eval_while(void)
 		ao_lisp_stack->state = eval_while_test;
 		if (!ao_lisp_stack_push())
 			return 0;
-		ao_lisp_stack->state = eval_sexpr;
 	}
 	return 1;
 }
@@ -547,11 +549,11 @@ ao_lisp_eval_while_test(void)
 
 	if (ao_lisp_v) {
 		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
-		if (ao_lisp_v)
-			ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
 		ao_lisp_stack->state = eval_while;
 		if (!ao_lisp_stack_push())
 			return 0;
+		ao_lisp_stack->state = eval_progn;
+		ao_lisp_stack->sexprs = ao_lisp_v;
 	}
 	else
 		ao_lisp_stack->state = eval_val;
@@ -567,6 +569,8 @@ ao_lisp_eval_macro(void)
 {
 	DBGI("macro: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
 
+	if (ao_lisp_v == AO_LISP_NIL)
+		ao_lisp_abort();
 	if (ao_lisp_poly_type(ao_lisp_v) == AO_LISP_CONS) {
 		*ao_lisp_poly_cons(ao_lisp_stack->sexprs) = *ao_lisp_poly_cons(ao_lisp_v);
 		ao_lisp_v = ao_lisp_stack->sexprs;
diff --git a/src/lisp/ao_lisp_lambda.c b/src/lisp/ao_lisp_lambda.c
index 186236f6..e2053a6f 100644
--- a/src/lisp/ao_lisp_lambda.c
+++ b/src/lisp/ao_lisp_lambda.c
@@ -78,8 +78,9 @@ ao_lisp_lambda_alloc(struct ao_lisp_cons *code, int args)
 	if (!lambda)
 		return AO_LISP_NIL;
 
-	if (!ao_lisp_check_argc(_ao_lisp_atom_lambda, code, 2, 2))
-		return AO_LISP_NIL;
+	if (!code->cdr)
+		return ao_lisp_error(AO_LISP_INVALID, "missing parameters to lambda");
+
 	if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, code, 0, AO_LISP_CONS, 1))
 		return AO_LISP_NIL;
 	f = 0;
@@ -135,7 +136,7 @@ ao_lisp_lambda_eval(void)
 	int			args_wanted;
 	int			args_provided;
 	int			f;
-	struct ao_lisp_cons	*vals
+	struct ao_lisp_cons	*vals;
 
 	DBGI("lambda "); DBG_POLY(ao_lisp_lambda_poly(lambda)); DBG("\n");
 
@@ -161,6 +162,10 @@ ao_lisp_lambda_eval(void)
 	args = ao_lisp_poly_cons(ao_lisp_arg(code, 0));
 	vals = ao_lisp_poly_cons(cons->cdr);
 
+	next_frame->prev = lambda->frame;
+	ao_lisp_frame_current = next_frame;
+	ao_lisp_stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
+
 	switch (lambda->args) {
 	case AO_LISP_FUNC_LAMBDA:
 		for (f = 0; f < args_wanted; f++) {
@@ -171,6 +176,7 @@ ao_lisp_lambda_eval(void)
 			vals = ao_lisp_poly_cons(vals->cdr);
 		}
 		ao_lisp_cons_free(cons);
+		cons = NULL;
 		break;
 	case AO_LISP_FUNC_LEXPR:
 	case AO_LISP_FUNC_NLAMBDA:
@@ -182,15 +188,15 @@ ao_lisp_lambda_eval(void)
 			args = ao_lisp_poly_cons(args->cdr);
 			vals = ao_lisp_poly_cons(vals->cdr);
 		}
-		DBGI("bind "); DBG_POLY(args->car); DBG(" = "); DBG_POLY(); DBG("\n");
+		DBGI("bind "); DBG_POLY(args->car); DBG(" = "); DBG_POLY(ao_lisp_cons_poly(vals)); DBG("\n");
 		next_frame->vals[f].atom = args->car;
 		next_frame->vals[f].val = ao_lisp_cons_poly(vals);
 		break;
+	default:
+		break;
 	}
-	next_frame->prev = lambda->frame;
 	DBGI("eval frame: "); DBG_POLY(ao_lisp_frame_poly(next_frame)); DBG("\n");
-	ao_lisp_frame_current = next_frame;
-	ao_lisp_stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
 	DBG_STACK();
-	return ao_lisp_arg(code, 1);
+	DBGI("eval code: "); DBG_POLY(code->cdr); DBG("\n");
+	return code->cdr;
 }