sequences.extras: move ??nth

[factor.git] / extra / sequences / extras / extras.factor

diff --git a/extra/sequences/extras/extras.factor b/extra/sequences/extras/extras.factor
index 5c8b8e4edcb6eb5997445fc42a1aea9de674ec84..ef66d0652f7a73d8f1f916ace0f3f8f7808cdfb2 100644 (file)
--- a/extra/sequences/extras/extras.factor
+++ b/extra/sequences/extras/extras.factor
@@ -333,6 +333,8 @@ PRIVATE>
 : nth-of ( seq n -- elt ) swap nth ; inline
 : set-nth-of ( seq n elt -- seq ) spin [ set-nth ] keep ; inline
 : ?nth-of ( seq n -- elt/f ) swap ?nth ; inline
+: ??nth ( n seq -- elt/f ? )
+    2dup bounds-check? [ nth-unsafe t ] [ 2drop f f ] if ; inline
 : ??nth-of ( seq n -- elt/f ? ) swap ??nth ; inline
 
 : reduce-of ( seq quot: ( prev elt -- next ) identity -- result )