1 files changed, 1 insertions, 0 deletions
diff --git a/apl9.h b/apl9.h
index cad5ae4..e33df18 100644
--- a/apl9.h
+++ b/apl9.h
@@ -367,6 +367,7 @@ Array *fnSelfReference2(Array *, Array *);
 /* Monadic operators from operators.c */
 Array *opEach(Datum *, Array *, Array *);
 Array *opSwitch(Datum *, Array *, Array *);
+Array *opKey(Datum *, Array *, Array *);
 Array *opOuterProduct(Datum *, Array *, Array *);
 Array *opSelfReference1(Datum *, Array *, Array *);