tuples: check length argument.

* lib.c (tuples): Check that n argument giving tuple size is a
is a positive integer.

* tests/012/seql.tl: Test case added.

1 files changed, 4 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 0fdc8ef0..7f797bb1 100644
--- a/lib.c
+++ b/lib.c
@@ -3575,8 +3575,12 @@ static val tuples_func(val n, val lcons)
 
 val tuples(val n, val seq, val fill)
 {
+  val self = lit("tuples");
   seq = nullify(seq);
 
+  if (!plusp(n) || !integerp(n))
+    uw_throwf(error_s, lit("~a: positive integer required, not ~s"), self, n, nao);
+
   if (!seq)
     return nil;