diff --git a/infer/src/checkers/abstractDomain.ml b/infer/src/checkers/abstractDomain.ml
new file mode 100644
index 000000000..8a2799569
--- /dev/null
+++ b/infer/src/checkers/abstractDomain.ml
@@ -0,0 +1,58 @@
+(*
+ * Copyright (c) 2016 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+module F = Format
+
+module type AbstractDomain = sig
+  type astate
+
+  val init : astate (* the initial state *)
+  val bot : astate
+  val is_bot : astate -> bool
+  val lteq : astate -> astate -> bool (* fst \sqsubseteq snd? *)
+  val join : astate -> astate -> astate
+  val widen : astate -> astate -> astate
+  val pp : F.formatter -> astate -> unit
+
+end
+
+module BotLiftedAbstractDomain (A : AbstractDomain) = struct
+  type astate =
+    | Bot
+    | NonBot of A.astate
+
+  let bot = Bot
+
+  let is_bot astate =
+    astate = Bot
+
+  let init = NonBot A.init
+
+  let lteq astate1 astate2 = match astate1, astate2 with
+    | Bot, _ -> true
+    | _ , Bot -> false
+    | NonBot a1, NonBot a2 -> A.lteq a1 a2
+
+  let join astate1 astate2 =
+    match astate1, astate2 with
+    | Bot, _ -> astate2
+    | _, Bot -> astate1
+    | NonBot a1, NonBot a2 -> NonBot (A.join a1 a2)
+
+  let widen astate1 astate2 =
+    match astate1, astate2 with
+    | Bot, _ -> astate2
+    | _, Bot -> astate1
+    | NonBot a1, NonBot a2 -> NonBot (A.widen a1 a2)
+
+  let pp fmt = function
+    | Bot -> F.fprintf fmt "_|_"
+    | NonBot astate -> A.pp fmt astate
+
+end
diff --git a/infer/src/checkers/transferFunctions.ml b/infer/src/checkers/transferFunctions.ml
new file mode 100644
index 000000000..97ec1a711
--- /dev/null
+++ b/infer/src/checkers/transferFunctions.ml
@@ -0,0 +1,17 @@
+(*
+ * Copyright (c) 2016 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+
+module type TransferFunctions = sig
+  type astate
+
+  (* {A} instr {A'} *)
+  val exec_instr : astate -> Sil.instr -> astate
+
+end