throw errors from phrase/{2,3} where expected (#1220)

2022-01-19 20:19:47 -07:00
parent 11b96875e0
commit 1854338ff4
1 changed files with 1 additions and 0 deletions
--- a/src/lib/dcgs.pl
+++ b/src/lib/dcgs.pl
@@ -72,6 +72,7 @@ phrase_((A -> B), S0, S, M) :-
 phrase_(phrase(NonTerminal), S0, S, M) :-
    phrase(NonTerminal, S0, S, M).
 phrase_([T|Ts], S0, S, _) :-
+    must_be(list, [T|Ts]),
    append([T|Ts], S, S0).