Use Lwt.Syntax.

.ocamlformat

@@ -0,0 +1 @@
+profile = default

lib/mehari.ml

@@ -1,3 +1,4 @@
+open Lwt.Syntax
 
 let cert =
   X509_lwt.private_of_pems
@@ -8,47 +9,47 @@ let init_socket addr port =
   let sockaddr = Unix.ADDR_INET (addr, port) in
   let socket = Lwt_unix.socket Unix.PF_INET Unix.SOCK_STREAM 0 in
   Lwt_unix.setsockopt socket Unix.SO_REUSEADDR true;
-  let%lwt () = Lwt_unix.bind socket sockaddr in
+  let* () = Lwt_unix.bind socket sockaddr in
   Lwt.return socket
 
 let create_srv_socket addr port =
-  let%lwt socket = init_socket addr port in
+  let* socket = init_socket addr port in
   Lwt_unix.listen socket 10;
   Lwt.return socket
 
 let accept sock =
-  let%lwt (sock_cl, addr) = Lwt_unix.accept sock in
+  let* (sock_cl, addr) = Lwt_unix.accept sock in
   let ic = Lwt_io.of_fd ~close:(fun () -> Lwt.return_unit) ~mode:Lwt_io.input sock_cl in
   let oc = Lwt_io.of_fd ~close:(fun () -> Lwt.return_unit) ~mode:Lwt_io.output sock_cl in
   Lwt.return ((ic,oc), addr, sock_cl)
 
 let write oc buff =
-  let%lwt () = Lwt_io.write oc buff in 
+  let* () = Lwt_io.write oc buff in
   Lwt_io.flush oc
 
 let read ic =
-  let%lwt buff = Lwt_io.read ic ~count:2048 in
+  let* buff = Lwt_io.read ic ~count:2048 in
   Printf.printf "%s%!" buff;
   Lwt.return buff
 
-let rec serve handler sock certchain = 
-  let%lwt (_, _, sock_cl) = accept sock in
-  let%lwt server = 
+let rec serve handler sock certchain =
+  let* (_, _, sock_cl) = accept sock in
+  let* server =
     Tls_lwt.Unix.server_of_fd
       (Tls.Config.server ~certificates:(`Single certchain) ()) sock_cl
   in
   let ic, oc = Tls_lwt.of_t server in
-  let%lwt () = handler ic oc in
-  let%lwt () = Tls_lwt.Unix.close_tls server in
+  let* () = handler ic oc in
+  let* () = Tls_lwt.Unix.close_tls server in
   serve handler sock certchain
 
 let start_server callback =
   let handle_request ic oc =
-    let%lwt buff = read ic in
+    let* buff = read ic in
     write oc @@ callback buff
   in
-  let%lwt sock = create_srv_socket Unix.inet_addr_loopback 1965 in
-  let%lwt certchain = cert in
+  let* sock = create_srv_socket Unix.inet_addr_loopback 1965 in
+  let* certchain = cert in
   serve handle_request sock certchain
 
 let run callback =