diff --git a/src/ligo/ast_simplified.ml b/src/ligo/ast_simplified.ml
index 51b116164..aac2c4aa2 100644
--- a/src/ligo/ast_simplified.ml
+++ b/src/ligo/ast_simplified.ml
@@ -715,16 +715,57 @@ module Simplify = struct
 end
 
 module Combinators = struct
+  let t_bool      : type_expression = Type_constant ("bool", [])
+  let t_string    : type_expression = Type_constant ("string", [])
+  let t_bytes     : type_expression = Type_constant ("bytes", [])
+  let t_int       : type_expression = Type_constant ("int", [])
+  let t_unit      : type_expression = Type_constant ("unit", [])
+  let t_tuple lst : type_expression = Type_tuple lst
+  let t_pair a b = t_tuple [a ; b]
+  let t_record m  : type_expression = (Type_record m)
+  let t_ez_record (lst:(string * type_expression) list) : type_expression =
+    let aux prev (k, v) = SMap.add k v prev in
+    let map = List.fold_left aux SMap.empty lst in
+    Type_record map
+
+  let t_record_ez lst =
+    let m = SMap.of_list lst in
+    t_record m
+
+  let t_sum m : type_expression = Type_sum m
+  let make_t_ez_sum (lst:(string * type_expression) list) : type_expression =
+    let aux prev (k, v) = SMap.add k v prev in
+    let map = List.fold_left aux SMap.empty lst in
+    Type_sum map
+
+  let t_function param result : type_expression = Type_function (param, result)
+
   let annotated_expression ?type_annotation expression = {expression ; type_annotation}
 
   let name (s : string) : name = s
 
+  let var (s : string) : expression = Variable s
+
   let unit  () : expression = Literal (Unit)
   let number n : expression = Literal (Number n)
   let bool   b : expression = Literal (Bool b)
   let string s : expression = Literal (String s)
   let bytes  b : expression = Literal (Bytes (Bytes.of_string b))
 
+  let lambda (binder : string)
+             (input_type : type_expression)
+             (output_type : type_expression)
+             (result : expression)
+             (body : block)
+      : expression =
+    Lambda {
+        binder = (name binder) ;
+        input_type = input_type ;
+        output_type = output_type ;
+        result = (ae result) ;
+        body ;
+      }
+
   let tuple (lst : ae list) : expression = Tuple lst
   let ez_tuple (lst : expression list) : expression =
     tuple (List.map (fun e -> ae e) lst)
diff --git a/src/ligo/ast_typed.ml b/src/ligo/ast_typed.ml
index c034b7f28..22aa156f5 100644
--- a/src/ligo/ast_typed.ml
+++ b/src/ligo/ast_typed.ml
@@ -346,8 +346,8 @@ module Combinators = struct
     let map = List.fold_left aux SMap.empty lst in
     type_value (Type_sum map) None
 
-  let t_function (param, result) s : type_value = type_value (Type_function (param, result)) s
-  let make_t_function f = t_function f None
+  let t_function param result s : type_value = type_value (Type_function (param, result)) s
+  let make_t_function param result = t_function param result None
 
   let get_annotation (x:annotated_expression) = x.type_annotation
 
diff --git a/src/ligo/test/typer_tests.ml b/src/ligo/test/typer_tests.ml
index a7fb56e52..4cdab7c1e 100644
--- a/src/ligo/test/typer_tests.ml
+++ b/src/ligo/test/typer_tests.ml
@@ -38,16 +38,23 @@ module TestExpressions = struct
   let string () : unit result = test_expression I.(string "s") O.make_t_string
   let bytes  () : unit result = test_expression I.(bytes "b")  O.make_t_bytes
 
+  let lambda () : unit result =
+    test_expression
+      I.(lambda "x" t_int t_int (var "x") [])
+      O.(make_t_function make_t_int make_t_int)
+
   let tuple () : unit result =
     test_expression
       I.(ez_tuple [number 32; string "foo"])
       O.(make_t_tuple [make_t_int; make_t_string])
 
   let constructor () : unit result =
-    test_expression
-      ~env:(E.env_sum_type O.[("foo", make_t_int); ("bar", make_t_string)])
+    let variant_foo_bar =
+      O.[("foo", make_t_int); ("bar", make_t_string)]
+    in test_expression
+      ~env:(E.env_sum_type variant_foo_bar)
       I.(constructor "foo" (ae @@ number 32))
-      O.(make_t_ez_sum [("foo", make_t_int); ("bar", make_t_string)])
+      O.(make_t_ez_sum variant_foo_bar)
 
   let record () : unit result =
     test_expression
@@ -68,4 +75,5 @@ let main = "Typer (from simplified AST)", [
     test "tuple"       TestExpressions.tuple ;
     test "constructor" TestExpressions.constructor ;
     test "record"      TestExpressions.record ;
+    test "lambda"      TestExpressions.lambda ;
   ]
diff --git a/src/ligo/transpiler.ml b/src/ligo/transpiler.ml
index 70b0ef073..16c50bdbc 100644
--- a/src/ligo/transpiler.ml
+++ b/src/ligo/transpiler.ml
@@ -266,7 +266,7 @@ let functionalize (e:AST.annotated_expression) : AST.lambda * AST.type_value =
     output_type = t ;
     result = e ;
     body = [Skip]
-  }, Combinators.(make_t_function (make_t_unit, t))
+  }, Combinators.(make_t_function make_t_unit t)
 
 let translate_entry (lst:AST.program) (name:string) : anon_function result =
   let rec aux acc (lst:AST.program) =
diff --git a/src/ligo/typer.ml b/src/ligo/typer.ml
index f3d8b36c5..aa7457e85 100644
--- a/src/ligo/typer.ml
+++ b/src/ligo/typer.ml
@@ -329,7 +329,7 @@ and type_annotated_expression (e:environment) (ae:I.annotated_expression) : O.an
       let e' = Environment.add e binder input_type in
       let%bind (body, e'') = type_block_full e' body in
       let%bind result = type_annotated_expression e'' result in
-      let%bind type_annotation = check @@ make_t_function (input_type, output_type) in
+      let%bind type_annotation = check @@ make_t_function input_type output_type in
       ok O.{expression = Lambda {binder;input_type;output_type;result;body} ; type_annotation}
   | Constant (name, lst) ->
       let%bind lst' = bind_list @@ List.map (type_annotated_expression e) lst in