Implement balanced binary tree and refactor

[tiger.ml.git] / exercises / ch01 / tree.ml

diff --git a/exercises/ch01/tree.ml b/exercises/ch01/tree.ml
index 94c2924..521b6cf 100644 (file)
--- a/exercises/ch01/tree.ml
+++ b/exercises/ch01/tree.ml
@@ -1,7 +1,4 @@
-module Array = ArrayLabels
-module List = ListLabels
-
-module type TREE = sig
+module type S = sig
   type ('k, 'v) t
 
   val empty : ('k, 'v) t
@@ -12,72 +9,5 @@ module type TREE = sig
 
   val member : ('k, 'v) t -> k:'k -> bool
 
-  val print
-    : ('k, 'v) t
-    -> k_to_string:('k -> string)
-    -> indent_level:string
-    -> unit
-end
-
-module BinaryTree : TREE = struct
-  type ('k, 'v) t =
-    | Node of 'k * 'v * ('k, 'v) t * ('k, 'v) t
-    | Leaf
-
-  let empty = Leaf
-
-  let rec set t ~k ~v =
-    match t with
-    | Leaf -> Node (k, v, Leaf, Leaf)
-    | Node (k', v', l, r) when k < k' -> Node (k', v', set l ~k ~v, r)
-    | Node (k', v', l, r) when k > k' -> Node (k', v', l, set r ~k ~v)
-    | Node (k, _, l, r) -> Node (k, v, l, r)
-
-  let rec get t ~k =
-    match t with
-    | Leaf -> None
-    | Node (k', _, l, _) when k < k' -> get l ~k
-    | Node (k', _, _, r) when k > k' -> get r ~k
-    | Node (_, v, _, _) -> Some v
-
-  let rec member t ~k =
-    match t with
-    | Leaf -> false
-    | Node (k', _, l, _) when k < k' -> member l ~k
-    | Node (k', _, _, r) when k > k' -> member r ~k
-    | Node _ -> true
-
-  let rec fold t ~f ~init:acc =
-    match t with
-    | Leaf -> acc
-    | Node (k, v, l, r) -> fold r ~f ~init:(f (fold l ~f ~init:acc) (k, v))
-
-  let print t ~k_to_string ~indent_level =
-    let (_, nodes) =
-      fold t
-        ~f:(fun (indentation, nodes) (k, _) ->
-            let indentation = indent_level ^ indentation in
-            let node = indentation ^ (k_to_string k) in
-            (indentation, node :: nodes)
-          )
-        ~init:(indent_level, [])
-    in
-    List.iter (List.rev nodes) ~f:print_endline
+  val to_dot : ('k, 'v) t -> k_to_string:('k -> string) -> string
 end
-
-let () =
-  let tree_a = BinaryTree.empty in
-  let tree_a = BinaryTree.set tree_a ~k:"k1" ~v:"v1" in
-  let tree_a = BinaryTree.set tree_a ~k:"k2" ~v:"v2" in
-  assert (BinaryTree.member tree_a ~k:"k1");
-  assert (BinaryTree.member tree_a ~k:"k2");
-  assert (Some "v1" = BinaryTree.get tree_a ~k:"k1");
-  assert (Some "v2" = BinaryTree.get tree_a ~k:"k2");
-  let tree_b =
-    Array.fold_left
-      (Sys.argv)
-      ~init:BinaryTree.empty
-      ~f:(fun t k -> BinaryTree.set t ~k ~v:())
-  in
-  Printf.printf "%B\n" (BinaryTree.member tree_b ~k:"a");
-  BinaryTree.print tree_b ~k_to_string:(fun x -> x) ~indent_level:"-";