diff --git a/src/Debugger.ml b/src/Debugger.ml
new file mode 100644
index 0000000..2272b0d
--- /dev/null
+++ b/src/Debugger.ml
@@ -0,0 +1,24 @@
+include DebuggerSigs
+
+module Make () = struct
+  type 'a Effect.t +=
+    | Debug : Loctext.t -> unit Effect.t
+    | CallBegin : Loctext.t -> unit Effect.t
+    | CallEnd : Loctext.t -> unit Effect.t
+
+  let emit_loctext t = Effect.perform @@ Debug t
+  let emit ?loc s = emit_loctext @@ Loctext.make ?loc s
+  let emitf ?loc = Loctext.kmakef ?loc emit_loctext
+
+  let trace_open_loctext t = Effect.perform @@ CallBegin t
+  let trace_close_loctext t = Effect.perform @@ CallEnd t
+
+  let trace ?loc s f =
+    trace_open_loctext (Loctext.make ?loc s);
+    Fun.protect f
+      ~finally:(fun () -> trace_close_loctext (Loctext.make ?loc s))
+  let tracef ?loc =
+    Text.kmakef @@ fun t f ->
+    trace_open_loctext (Range.locate_opt loc t);
+    Fun.protect f ~finally:(fun () -> trace_close_loctext (Range.locate_opt loc t))
+end
diff --git a/src/Debugger.mli b/src/Debugger.mli
new file mode 100644
index 0000000..b67cf24
--- /dev/null
+++ b/src/Debugger.mli
@@ -0,0 +1,3 @@
+include module type of DebuggerSigs
+
+module Make () : S
diff --git a/src/DebuggerSigs.ml b/src/DebuggerSigs.ml
new file mode 100644
index 0000000..5bf4578
--- /dev/null
+++ b/src/DebuggerSigs.ml
@@ -0,0 +1,8 @@
+module type S =
+sig
+  val emit : ?loc:Range.t -> string -> unit
+  val emitf : ?loc:Range.t -> ('a, Format.formatter, unit, unit) format4 -> 'a
+  val trace : ?loc:Range.t -> string -> (unit -> 'a) -> 'a
+  val tracef : ?loc:Range.t -> ('b, Format.formatter, unit, (unit -> 'a) -> 'a) format4 -> 'b
+  val run : emit:(Loctext.t -> unit) -> trace:([`Open | `Close] -> Loctext.t -> unit) -> (unit -> 'a) -> 'a
+end