graphviz: better stack effect for with-preview.

diff --git a/extra/graphviz/render/render.factor b/extra/graphviz/render/render.factor
index 110092a503c85bd6c1fb3478771f5a761d97de10..09157cd613cdafb8f37dc628a1bcc6062a6ae85d 100644 (file)
--- a/extra/graphviz/render/render.factor
+++ b/extra/graphviz/render/render.factor
@@ -115,7 +115,7 @@ PRIVATE>
         [ unsupported-preview-format ]
     } case ;
 
-:: with-preview ( graph quot -- )
+:: with-preview ( ..a graph quot: ( ..a path -- ..b ) -- ..b )
     [
         "preview" ".dot" [| code-file |
             "preview" preview-extension [| image-file |