diff --git a/lib/dune b/lib/dune
index 773e84b..17c20f7 100644
--- a/lib/dune
+++ b/lib/dune
@@ -62,7 +62,7 @@
  (name git)
  (public_name bob.git)
  (modules git)
- (libraries bob.fiber bob.stream cstruct digestif))
+ (libraries bob.fiber bob.stream cstruct carton digestif))
 
 (library
  (name pack)
diff --git a/lib/git.ml b/lib/git.ml
index 82d0345..e22d2c2 100644
--- a/lib/git.ml
+++ b/lib/git.ml
@@ -7,11 +7,7 @@ module Log = (val Logs.src_log src : Logs.LOG)
 module SHA1 = struct
   include Digestif.SHA1
 
-  let hash x = Hashtbl.hash x
   let length = digest_size
-  let feed = feed_bigstring
-  let null = digest_string ""
-  let compare a b = String.compare (to_raw_string a) (to_raw_string b)
 
   let sink_bigstring ?(ctx = empty) () =
     Stream.Sink.make ~init:(Fiber.always ctx)
@@ -57,6 +53,9 @@ let tree_of_string ?path str =
 let v_space = Cstruct.string " "
 let v_null = Cstruct.string "\x00"
 
+type elt = [ `Reg of Bob_fpath.t * SHA1.t | `Dir of Bob_fpath.t * SHA1.t ]
+type tree = elt list
+
 let tree_of_cstruct ?path contents =
   let path_with ~name =
     match path with
@@ -114,31 +113,6 @@ module Filesystem = struct
       try Sys.readdir (Bob_fpath.to_string d) with _exn -> [||]
     in
     Array.to_list <.> readdir
-
-  let rec traverse ~get ~add visited stack ~f acc =
-    match stack with
-    | [] -> Fiber.return acc
-    | x :: r ->
-        if List.exists (Bob_fpath.equal x) visited then
-          traverse ~get ~add visited r ~f acc
-        else
-          let open Fiber in
-          let contents = get x in
-          traverse ~get ~add (x :: visited) (add contents stack) ~f acc >>= f x
-
-  let fold ?(dotfiles = false) ~f acc paths =
-    let dir_child d acc bname =
-      if (not dotfiles) && bname.[0] = '.' then acc
-      else Bob_fpath.(d / bname) :: acc
-    in
-    let add stack vs = vs @ stack in
-    let get path =
-      let entries = readdir path in
-      List.fold_left (dir_child path) [] entries
-    in
-    traverse ~get ~add [] paths ~f acc
-
-  let fold ?dotfiles ~f acc d = fold ?dotfiles ~f acc [ d ]
 end
 
 let serialize_directory entries =
diff --git a/lib/git.mli b/lib/git.mli
new file mode 100644
index 0000000..a5d9d92
--- /dev/null
+++ b/lib/git.mli
@@ -0,0 +1,29 @@
+type elt =
+  [ `Reg of Bob_fpath.t * Digestif.SHA1.t
+  | `Dir of Bob_fpath.t * Digestif.SHA1.t ]
+
+type tree = elt list
+
+val tree_of_string : ?path:Bob_fpath.t -> string -> tree
+val tree_of_cstruct : ?path:Bob_fpath.t -> Stdbob.bigstring -> elt Stream.source
+
+val digest :
+  kind:Carton.kind ->
+  ?off:int ->
+  ?len:int ->
+  Stdbob.bigstring ->
+  Digestif.SHA1.t
+
+val serialize_directory :
+  (Bob_fpath.t * Digestif.SHA1.t) list -> string Stream.stream
+
+val hash_of_root :
+  real_length:int -> root:Bob_fpath.t -> Digestif.SHA1.t -> Digestif.SHA1.t
+
+val hash_of_directory :
+  root:Bob_fpath.t ->
+  (Bob_fpath.t, Digestif.SHA1.t * [ `Dir | `Reg | `Root ]) Hashtbl.t ->
+  Bob_fpath.t ->
+  Digestif.SHA1.t Fiber.t
+
+val hash_of_filename : Bob_fpath.t -> Digestif.SHA1.t Fiber.t