fear(zipper): add function to join two zippers

2 files changed, 5 insertions, 0 deletions

diff --git a/lib/zipper.ml b/lib/zipper.ml
index 2322a58..30be8eb 100644
--- a/lib/zipper.ml
+++ b/lib/zipper.ml
@@ -87,6 +87,7 @@ let split z =
   ( { z with after = Sequence.empty },
     { z with pos = 0; before = Sequence.empty } )
 
+let join z1 z2 = { z1 with after = z2.after }
 let iter_before f z = Sequence.iter ~f z.before
 let iter_after f z = Sequence.iter ~f z.after
 
diff --git a/lib/zipper.mli b/lib/zipper.mli
index c3c79a6..beeb181 100644
--- a/lib/zipper.mli
+++ b/lib/zipper.mli
@@ -145,6 +145,10 @@ val split : 'a zipper -> 'a zipper * 'a zipper
 (** [split z] splits the zipper in two. [([3; 2; 1], [4; 5])] becomes
     [([3; 2; 1], []), ([], [4; 5])]. *)
 
+val join : 'a zipper -> 'a zipper -> 'a zipper
+(** [join z1 z2] creates a new zipper using [before z1] and [after z2].
+    [([3; 2; 1], []) ([4; 2], [4; 5])] becomes [([3; 2; 1], [4; 5])]. *)
+
 (** {1 Consuming zippers} *)
 
 (** Since zippers are based on sequences, iterating over zippers