[real-world-ocaml] update

Author: nojima

real-world-ocaml/counter.ml

@@ -0,0 +1,15 @@
+open Base
+
+type t = (string, int, String.comparator_witness) Map.t
+
+let empty = Map.empty (module String)
+
+let to_list t = Map.to_alist t
+
+let touch t s =
+  let count =
+    match Map.find t s with
+    | None -> 0
+    | Some x -> x
+  in
+  Map.set t ~key:s ~data:(count + 1)

real-world-ocaml/counter.mli

@@ -0,0 +1,14 @@
+open Base
+
+(** A collection of string frequency counts *)
+type t
+
+(** The empty set of frequency counts *)
+val empty : t
+
+(** Bump the frequency count for the given string *)
+val touch : t -> string -> t
+
+(** Converts the set of frequency counts to an association list. A string shows
+    up at most once, and the counts are >= 1. *)
+val to_list : t -> (string * int) list