From 4a57c3c56436c483523cc7247d9c207a90c3b8e4 Mon Sep 17 00:00:00 2001
From: Devine Lu Linvega <aliceffekt@gmail.com>
Date: Fri, 10 May 2024 14:25:54 -0700
Subject: [PATCH] Catch empty rules

---
 examples/tests.modal | 3 ++-
 src/modal.c          | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/examples/tests.modal b/examples/tests.modal
index e2c7881..4f58865 100644
--- a/examples/tests.modal
+++ b/examples/tests.modal
@@ -81,7 +81,8 @@ abc ?(?x) def = abc (lambda 2/2) test
 
 <> (incomplete-basic)
 <> (incomplete-reg ?x)
-<> (waste-rule) *
+<> <>
+<> () ()
 
 (incomplete-basic) = () (incomplete 1/4) test
 (incomplete-reg abcdef) = () (incomplete 2/4) test
diff --git a/src/modal.c b/src/modal.c
index 35f7992..55ef37f 100644
--- a/src/modal.c
+++ b/src/modal.c
@@ -226,7 +226,7 @@ parse_frag(char **side, char *s)
 {
 	char c, *cap;
 	while((c = *s) && c == ' ') s++;
-	if(c == ')' || (c == '<' || c == '>'))
+	if(c == ')' || c == '<' || c == '>' || (c == '(' && s[1] == ')'))
 		*side = NULL;
 	else {
 		cap = walk(s), *side = dict_;
@@ -315,7 +315,7 @@ main(int argc, char **argv)
 		return !printf("usage: modal [-vqn] source.modal\n");
 	for(i = 1; i < argc && *argv[i] == '-'; i++) {
 		switch(argv[i][1]) {
-		case 'v': /* version */ return !printf("Modal Interpreter, 9 May 2024.\n");
+		case 'v': /* version */ return !printf("Modal Interpreter, 10 May 2024.\n");
 		case 'q': /* quiet */ quiet = 1; break;
 		case 'p': /* debug */ debug = 1; break;
 		case 'a': /* access */ access = 1; break;