diff --git a/Makefile b/Makefile
index 8764344b..bc746532 100644
--- a/Makefile
+++ b/Makefile
@@ -13,6 +13,9 @@ clean:
 doc:
 	@dune build @doc
 
+fmt:
+	@dune build @fmt --auto-promote
+
 VERSION=$(shell awk '/^version:/ {print $$2}' linol.opam)
 
 update_next_tag:
diff --git a/src/blocking_IO.ml b/src/blocking_IO.ml
index af17c500..5791d2bf 100644
--- a/src/blocking_IO.ml
+++ b/src/blocking_IO.ml
@@ -10,11 +10,9 @@ let ( let* ) x f = f x
 let ( and+ ) a b = a, b
 let return x = x
 let failwith = failwith
-
 let fail = Printexc.raise_with_backtrace
-
-let stdin = fun () -> stdin
-let stdout = fun () -> stdout
+let stdin () = stdin
+let stdout () = stdout
 
 let default_spawn f =
   let run () =
diff --git a/src/eio/linol_eio.ml b/src/eio/linol_eio.ml
index a3cb606c..42b35d07 100644
--- a/src/eio/linol_eio.ml
+++ b/src/eio/linol_eio.ml
@@ -15,11 +15,15 @@ module IO_eio :
   let failwith = failwith
   let fail = raise
 
-  let catch f handler = try f () with exn ->
-    let bt = Printexc.get_raw_backtrace () in
-    handler exn bt
+  let catch f handler =
+    try f ()
+    with exn ->
+      let bt = Printexc.get_raw_backtrace () in
+      handler exn bt
+
+  let stdin env =
+    Eio.Buf_read.of_flow ~max_size:1_000_000 (Eio.Stdenv.stdin env)
 
-  let stdin env = Eio.Buf_read.of_flow ~max_size:1_000_000 (Eio.Stdenv.stdin env)
   let stdout = Eio.Stdenv.stdout
 
   type env = Eio_unix.Stdenv.base
@@ -27,29 +31,28 @@ module IO_eio :
   type out_channel = Eio_unix.sink_ty Eio.Std.r
 
   let write_string out_ch str = Eio.Flow.copy_string str out_ch
+
   let write out_ch bytes off len =
     Eio.Buf_write.with_flow out_ch @@ fun w ->
     Eio.Buf_write.bytes w ~off ~len bytes
+
   let read in_ch bytes off len =
     let str = Eio.Buf_read.take len in_ch in
     Bytes.blit_string str off bytes 0 len
-  let read_line in_ch =
-    Eio.Buf_read.line in_ch
+
+  let read_line in_ch = Eio.Buf_read.line in_ch
 end
 
 (** Spawn function. *)
 let spawn f =
   let promise, resolver = Eio.Promise.create () in
-  begin
-    try
-      f ();
-      Eio.Promise.resolve_ok resolver ()
-    with
-      exn ->
-      (Printf.eprintf "uncaught exception in `spawn`:\n%s\n%!"
-        (Printexc.to_string exn));
-      Eio.Promise.resolve_error resolver exn
-    end;
+  (try
+     f ();
+     Eio.Promise.resolve_ok resolver ()
+   with exn ->
+     Printf.eprintf "uncaught exception in `spawn`:\n%s\n%!"
+       (Printexc.to_string exn);
+     Eio.Promise.resolve_error resolver exn);
 
   Eio.Promise.await_exn promise
 
diff --git a/src/jsonrpc2.ml b/src/jsonrpc2.ml
index 48c292c0..9aecefd3 100644
--- a/src/jsonrpc2.ml
+++ b/src/jsonrpc2.ml
@@ -22,7 +22,11 @@ module type S = sig
     t
 
   val create_stdio :
-    ?on_received:(json -> unit) -> ?on_sent:(json -> unit) -> env:IO.env -> server -> t
+    ?on_received:(json -> unit) ->
+    ?on_sent:(json -> unit) ->
+    env:IO.env ->
+    server ->
+    t
 
   val send_server_notification : t -> Lsp.Server_notification.t -> unit IO.t
 
diff --git a/src/jsonrpc2.mli b/src/jsonrpc2.mli
index 2ed46b04..96c2acf6 100644
--- a/src/jsonrpc2.mli
+++ b/src/jsonrpc2.mli
@@ -24,7 +24,11 @@ module type S = sig
   (** Create a connection from the pair of channels *)
 
   val create_stdio :
-    ?on_received:(json -> unit) -> ?on_sent:(json -> unit) -> env:IO.env -> server -> t
+    ?on_received:(json -> unit) ->
+    ?on_sent:(json -> unit) ->
+    env:IO.env ->
+    server ->
+    t
   (** Create a connection using stdin/stdout *)
 
   val send_server_notification : t -> Lsp.Server_notification.t -> unit IO.t
diff --git a/src/lwt/linol_lwt.ml b/src/lwt/linol_lwt.ml
index 432527bf..5b8b2889 100644
--- a/src/lwt/linol_lwt.ml
+++ b/src/lwt/linol_lwt.ml
@@ -18,8 +18,8 @@ module IO_lwt :
 
   let return = Lwt.return
   let failwith = Lwt.fail_with
-  let stdin = fun () -> Lwt_io.stdin
-  let stdout = fun () -> Lwt_io.stdout
+  let stdin () = Lwt_io.stdin
+  let stdout () = Lwt_io.stdout
 
   type env = unit
   type in_channel = Lwt_io.input Lwt_io.channel