diff --git a/src/lib_utils/tuple.ml b/src/lib_utils/tuple.ml
index a32af6f8b..ad451e74d 100644
--- a/src/lib_utils/tuple.ml
+++ b/src/lib_utils/tuple.ml
@@ -1,3 +1,4 @@
+let map_h_2 f g (a , b) = (f a , g b)
 let map2 f (a, b) = (f a, f b)
 let apply2 f (a, b) = f a b
 let list2 (a, b) = [a;b]
diff --git a/src/ligo/operators.ml b/src/ligo/operators.ml
new file mode 100644
index 000000000..fa59a47ae
--- /dev/null
+++ b/src/ligo/operators.ml
@@ -0,0 +1,177 @@
+open Trace
+
+let type_constants = [
+  ("unit" , 0) ;
+  ("string" , 0) ;
+  ("nat" , 0) ;
+  ("int" , 0) ;
+  ("bool" , 0) ;
+  ("operation" , 0) ;
+  ("list" , 1) ;
+  ("option" , 1) ;
+  ("set" , 1) ;
+  ("map" , 2) ;
+]
+
+let constants = [
+  ("get_force" , 2) ;
+  ("size" , 1) ;
+  ("int" , 1) ;
+]
+
+module Typer = struct
+  module Errors = struct
+    let wrong_param_number = fun name ->
+      let title () = "wrong number of params" in
+      let full () = name in
+      error title full
+  end
+
+  open Ast_typed
+
+  type typer_predicate = type_value list -> bool
+  type type_result = string * type_value
+  type typer' = type_value list -> type_value option -> type_result result
+  type typer = string * (typer_predicate * typer') list
+
+  let predicate_0 : typer_predicate = fun lst ->
+    match lst with
+    | [] -> true
+    | _ -> false
+
+  let predicate_1 : (type_value -> bool) -> typer_predicate = fun f lst ->
+    match lst with
+    | [ a ] -> f a
+    | _ -> false
+
+  let predicate_2 : (type_value -> type_value -> bool) -> typer_predicate = fun f lst ->
+    match lst with
+    | [ a ; b ] -> f a b
+    | _ -> false
+
+  let predicate_3 : (type_value -> type_value -> type_value -> bool) -> typer_predicate = fun f lst ->
+    match lst with
+    | [ a ; b ; c ] -> f a b c
+    | _ -> false
+
+  let true_1 = predicate_1 (fun _ -> true)
+  let true_2 = predicate_2 (fun _ _ -> true)
+  let true_3 = predicate_3 (fun _ _ _ -> true)
+
+  let eq_2 : type_value -> typer_predicate = fun v ->
+    let aux = fun a b -> type_value_eq (a, v) && type_value_eq (b, v) in
+    predicate_2 aux
+
+  let typer'_0 : (type_value option -> type_result result) -> typer' = fun f lst tv ->
+    match lst with
+    | [] -> f tv
+    | _ -> simple_fail "!!!"
+
+  let typer'_1 : (type_value -> type_result result) -> typer' = fun f lst _ ->
+    match lst with
+    | [ a ] -> f a
+    | _ -> simple_fail "!!!"
+
+  let typer'_2 : (type_value -> type_value -> type_result result) -> typer' = fun f lst _ ->
+    match lst with
+    | [ a ; b ] -> f a b
+    | _ -> simple_fail "!!!"
+
+  let typer'_3 : (type_value -> type_value -> type_value -> type_result result) -> typer' = fun f lst _ ->
+    match lst with
+    | [ a ; b ; c ] -> f a b c
+    | _ -> simple_fail "!!!"
+
+  let constant_2 : string -> type_value -> typer' = fun s tv ->
+    let aux = fun _ _ -> ok (s, tv) in
+    typer'_2 aux
+
+  let make_2 : string -> _ list -> typer = fun name pfs ->
+    (name , List.map (Tuple.map_h_2 predicate_2 typer'_2) pfs)
+
+  let same_2 : string -> (string * type_value) list -> typer = fun s lst ->
+    let aux (s, tv) = eq_2 tv, constant_2 s tv in
+    (s , List.map aux lst)
+
+  let very_same_2 : string -> type_value -> typer = fun s tv -> same_2 s [s , tv]
+
+  open Combinators
+
+  let comparator : string -> typer = fun s -> s , [
+      (eq_2 (t_int ()), constant_2 s (t_bool ())) ;
+      (eq_2 (t_nat ()), constant_2 s (t_bool ())) ;
+    ]
+
+  let boolean_operator_2 : string -> typer = fun s -> very_same_2 s (t_bool ())
+
+  let none = "NONE" , [
+      predicate_0 , typer'_0 (fun tv_opt -> match tv_opt with
+          | None -> simple_fail "untyped NONE"
+          | Some t -> ok ("NONE", t))
+    ]
+
+  let some = "SOME" , [
+      true_1 , typer'_1 (fun s -> ok ("SOME", t_option s ())) ;
+    ]
+
+  let map_remove : typer = "MAP_REMOVE" , [
+      (true_2 , typer'_2 (fun k m ->
+          let%bind (src, _) = get_t_map m in
+          let%bind () = assert_type_value_eq (src, k) in
+          ok ("MAP_REMOVE", m)
+        ))
+    ]
+
+  let map_update : typer = "MAP_UPDATE" , [
+      (true_3 , typer'_3 (fun k v m ->
+           let%bind (src, dst) = get_t_map m in
+           let%bind () = assert_type_value_eq (src, k) in
+           let%bind () = assert_type_value_eq (dst, v) in
+           ok ("MAP_UPDATE", m)))
+    ]
+
+  let size : typer = "size" , [
+      (true_1, typer'_1 (fun t ->
+           let%bind () = bind_or (assert_t_map t, assert_t_list t) in
+           ok ("SIZE", t_nat ())))
+    ]
+
+  let get_force : typer = "get_force" , [
+      (true_2, typer'_2 (fun i_ty m_ty ->
+           let%bind (src, dst) = get_t_map m_ty in
+           let%bind _ = assert_type_value_eq (src, i_ty) in
+           ok ("GET_FORCE", dst)))
+    ]
+
+  let int : typer = "int" , [
+      (true_1, typer'_1 (fun t ->
+           let%bind () = assert_t_nat t in
+           ok ("INT", t_int ())))
+    ]
+
+  let constant_typers = Map.String.of_list [
+    same_2 "ADD" [
+      ("ADD_INT" , t_int ()) ;
+      ("ADD_NAT" , t_nat ()) ;
+      ("CONCAT" , t_string ()) ;
+    ] ;
+    same_2 "TIMES" [
+      ("TIMES_INT" , t_int ()) ;
+      ("TIMES_NAT" , t_nat ()) ;
+    ] ;
+    none ;
+    some ;
+    comparator "EQ" ;
+    comparator "LT" ;
+    comparator "GT" ;
+    comparator "LE" ;
+    comparator "GE" ;
+    boolean_operator_2 "OR" ;
+    boolean_operator_2 "AND" ;
+    map_remove ;
+    map_update ;
+    int ;
+  ]
+
+end
+