IrminHistory.re

module Mem_store = Irmin_mem.KV(Irmin.Contents.String);

let config = Irmin_mem.config();

let repo = Mem_store.Repo.v(config);

open Lwt.Infix;
let master = config => Mem_store.Repo.v(config) >>= Mem_store.master;

let info = msg => {
  let date = Int64.zero;
  let author = "author";
  Irmin.Info.v(~date, ~author, msg);
};

let infof = fmt => Fmt.kstrf((str, ()) => info(str), fmt);
let main =
  Mem_store.Repo.v(config)
  >>= Mem_store.master
  >>= (
    t =>
      Mem_store.history(t)
      >|= (
        history_res =>
          Printf.printf(
            "0. is the history empty? %b\n",
            Mem_store.History.is_empty(history_res),
          )
      )
      >>= (
        () => {
          print_endline("setting [a,b,c]");
          Mem_store.set_exn(
            t,
            ["a", "b", "c"],
            "Message 1",
            ~info=infof("COMMIT 1"),
          );
        }
      )
      >>= (
        () =>
          Mem_store.get(t, ["a", "b", "c"])
          >|= (s => print_endline("data at [a,b,c] is " ++ s))
      )
      >>= (
        () =>
          Mem_store.history(t)
          >|= (
            history_res =>
              Printf.printf(
                "1. is the history empty? %b\n",
                Mem_store.History.is_empty(history_res),
              )
          )
      )
      >>= (
        () =>
          {
            print_endline("setting [a,b,d]");
            Mem_store.set_exn(
              t,
              ["a", "b", "d"],
              "Message 2",
              ~info=infof("COMMIT 2"),
            );
          }
          >>= (
            () =>
              Mem_store.get(t, ["a", "b", "c"])
              >|= (s => print_endline("data at [a,b,c] is " ++ s))
          )
          >>= (
            () =>
              Mem_store.get(t, ["a", "b", "d"])
              >|= (s => print_endline("data at [a,b,d] is " ++ s))
          )
          >>= (
            () =>
              Mem_store.history(t)
              >|= (
                history_res =>
                  Printf.printf(
                    "2. is the history empty? %b\n",
                    Mem_store.History.is_empty(history_res),
                  )
              )
          )
      )
  );

prints the following

0. is the history empty? true
setting [a,b,c]
data at [a,b,c] is Message 1
1. is the history empty? true
setting [a,b,d]
data at [a,b,c] is Message 1
data at [a,b,d] is Message 2
2. is the history empty? false

if it matters, this is compiled with js_of_ocaml and run with node...