diff --git a/src/environment/bool.ml b/src/environment/bool.ml
index 611c84dfd..d3fea07eb 100644
--- a/src/environment/bool.ml
+++ b/src/environment/bool.ml
@@ -1,4 +1,8 @@
 open Ast_typed
 open Stage_common.Constant
 
-let environment = env_sum_type ~type_name:t_bool @@ [(Constructor "true",{ctor_type=t_unit ();michelson_annotation=None;ctor_decl_pos=0});(Constructor "false",{ctor_type=t_unit ();michelson_annotation=None;ctor_decl_pos=1})]
+let environment = Ast_typed.Environment.add_ez_sum_type ~type_name:t_bool @@ 
+  [
+    (Constructor "true" ,{ctor_type=t_unit ();michelson_annotation=None;ctor_decl_pos=0});
+    (Constructor "false",{ctor_type=t_unit ();michelson_annotation=None;ctor_decl_pos=1});
+  ]
diff --git a/src/passes/10-transpiler/transpiler.ml b/src/passes/10-transpiler/transpiler.ml
index 01698f300..5ea4ea43f 100644
--- a/src/passes/10-transpiler/transpiler.ml
+++ b/src/passes/10-transpiler/transpiler.ml
@@ -374,9 +374,6 @@ let rec transpile_literal : AST.literal -> value = fun l -> match l with
   | Literal_unit -> D_unit
   | Literal_void -> D_none
 
-(* and transpile_environment_element_type : AST.environment_element -> type_expression result = fun ele ->
- *   transpile_type ele.type_value *)
-
 and tree_of_sum : AST.type_expression -> (AST.constructor' * AST.type_expression) Append_tree.t result = fun t ->
   let%bind map_tv = get_t_sum t in
   let kt_list = List.map (fun (k,({ctor_type;_}:AST.ctor_content)) -> (k,ctor_type)) (kv_list_of_cmap map_tv) in
@@ -397,10 +394,6 @@ and transpile_annotated_expression (ae:AST.expression) : expression result =
     return (E_let_in ((let_binder, rhs'.type_expression), inline, rhs', result'))
   | E_literal l -> return @@ E_literal (transpile_literal l)
   | E_variable name -> (
-      (* let%bind ele =
-       *   trace_option (corner_case ~loc:__LOC__ "name not in environment") @@
-       *   AST.Environment.get_opt name ae.environment in
-       * let%bind tv = transpile_environment_element_type tv in *)
       return @@ E_variable (name)
     )
   | E_application {lamb; args} ->
@@ -441,7 +434,6 @@ and transpile_annotated_expression (ae:AST.expression) : expression result =
       return ~tv ae
     )
   | E_record m -> (
-    (*list_of_lmap to record_to_list*)
       let node = Append_tree.of_list @@ Ast_typed.Helpers.list_of_record_or_tuple m in
       let aux a b : expression result =
         let%bind a = a in
@@ -779,7 +771,9 @@ let transpile_program (lst : AST.program) : program result =
   ok statements
 
 (* check whether the storage contains a big_map, if yes, check that
-  it appears on the left hand side of a pair *)
+  it appears on the left hand side of a pair 
+  TODO : checking should appears in check_pass.  
+*)
 let check_storage f ty loc : (anon_function * _) result =
   let rec aux (t:type_expression) on_big_map =
     match t.type_content with
diff --git a/src/passes/8-typer-old/typer.ml b/src/passes/8-typer-old/typer.ml
index a60edf107..ca2a123a7 100644
--- a/src/passes/8-typer-old/typer.ml
+++ b/src/passes/8-typer-old/typer.ml
@@ -494,27 +494,25 @@ let rec type_program (p:I.program) : (O.program * O.typer_state) result =
     let%bind ed' = (bind_map_location (type_declaration e (Solver.placeholder_for_state_of_new_typer ()))) d in
     let loc : 'a . 'a Location.wrap -> _ -> _ = fun x v -> Location.wrap ~loc:x.location v in
     let (e', _placeholder_for_state_of_new_typer , d') = Location.unwrap ed' in
-    match d' with
-    | None -> ok (e', acc)
-    | Some d' -> ok (e', loc ed' d' :: acc)
+    ok (e', loc ed' d' :: acc)
   in
   let%bind (_, lst) =
     trace (fun () -> program_error p ()) @@
     bind_fold_list aux (DEnv.default, []) p in
   ok @@ (List.rev lst , (Solver.placeholder_for_state_of_new_typer ()))
 
-and type_declaration env (_placeholder_for_state_of_new_typer : O.typer_state) : I.declaration -> (environment * O.typer_state * O.declaration option) result = function
+and type_declaration env (_placeholder_for_state_of_new_typer : O.typer_state) : I.declaration -> (environment * O.typer_state * O.declaration) result = function
   | Declaration_type (type_binder , type_expr) ->
       let%bind tv = evaluate_type env type_expr in
       let env' = Environment.add_type (type_binder) tv env in
-      ok (env', (Solver.placeholder_for_state_of_new_typer ()) , Some (O.Declaration_type { type_binder ; type_expr = tv } ))
+      ok (env', (Solver.placeholder_for_state_of_new_typer ()) , (O.Declaration_type { type_binder ; type_expr = tv } ))
   | Declaration_constant (binder , tv_opt , inline, expression) -> (
       let%bind tv'_opt = bind_map_option (evaluate_type env) tv_opt in
       let%bind expr =
         trace (constant_declaration_error binder expression tv'_opt) @@
         type_expression' ?tv_opt:tv'_opt env expression in
       let post_env = Environment.add_ez_declaration binder expr env in
-      ok (post_env, (Solver.placeholder_for_state_of_new_typer ()) , Some (O.Declaration_constant { binder ; expr ; inline}))
+      ok (post_env, (Solver.placeholder_for_state_of_new_typer ()) , (O.Declaration_constant { binder ; expr ; inline}))
     )
 
 and type_match : (environment -> I.expression -> O.expression result) -> environment -> O.type_expression -> I.matching_expr -> I.expression -> Location.t -> O.matching_expr result =
diff --git a/src/passes/8-typer-old/typer.mli b/src/passes/8-typer-old/typer.mli
index ff7009a8c..531a6b751 100644
--- a/src/passes/8-typer-old/typer.mli
+++ b/src/passes/8-typer-old/typer.mli
@@ -39,7 +39,7 @@ module Errors : sig
 end
 
 val type_program : I.program -> (O.program * O.typer_state) result
-val type_declaration : environment -> O.typer_state -> I.declaration -> (environment * O.typer_state * O.declaration option) result
+val type_declaration : environment -> O.typer_state -> I.declaration -> (environment * O.typer_state * O.declaration) result
 (* val type_match : (environment -> 'i -> 'o result) -> environment -> O.type_value -> 'i I.matching -> I.expression -> Location.t -> 'o O.matching result *)
 val evaluate_type : environment -> I.type_expression -> O.type_expression result
 val type_expression : environment -> O.typer_state -> ?tv_opt:O.type_expression -> I.expression -> (O.expression * O.typer_state) result
diff --git a/src/passes/9-self_ast_typed/self_ast_typed.ml b/src/passes/9-self_ast_typed/self_ast_typed.ml
index 35821b3d6..442564638 100644
--- a/src/passes/9-self_ast_typed/self_ast_typed.ml
+++ b/src/passes/9-self_ast_typed/self_ast_typed.ml
@@ -13,7 +13,6 @@ let contract_passes = [
 let all_program program =
   let all_p = List.map Helpers.map_program all_passes in
   let%bind program' = bind_chain all_p program in
-  (* let program'' = Recompute_environment.program Environment.default program' in *)
   ok program'
 
 let all_expression =
diff --git a/src/stages/4-ast_typed/ast_typed.ml b/src/stages/4-ast_typed/ast_typed.ml
index bd70790a7..9a1250ecc 100644
--- a/src/stages/4-ast_typed/ast_typed.ml
+++ b/src/stages/4-ast_typed/ast_typed.ml
@@ -4,7 +4,6 @@ module PP = PP
 module PP_generic = PP_generic
 module Combinators = struct
   include Combinators
-  include Combinators_environment
 end
 module Misc = struct
   include Misc
diff --git a/src/stages/4-ast_typed/combinators_environment.ml b/src/stages/4-ast_typed/combinators_environment.ml
deleted file mode 100644
index 401d9b4c4..000000000
--- a/src/stages/4-ast_typed/combinators_environment.ml
+++ /dev/null
@@ -1,25 +0,0 @@
-open Types
-open Combinators
-
-(* let make_a_e_empty expression type_annotation = make_e expression type_annotation Environment.empty *)
-
-(* let e_a_empty_unit = e_a_unit Environment.empty
- * let e_a_empty_int n = e_a_int n Environment.empty
- * let e_a_empty_nat n = e_a_nat n Environment.empty
- * let e_a_empty_mutez n = e_a_mutez n Environment.empty
- * let e_a_empty_bool b = e_a_bool b Environment.empty
- * let e_a_empty_string s = e_a_string s Environment.empty
- * let e_a_empty_address s = e_a_address s Environment.empty
- * let e_a_empty_pair a b = e_a_pair a b Environment.empty
- * let e_a_empty_some s = e_a_some s Environment.empty
- * let e_a_empty_none t = e_a_none t Environment.empty
- * let e_a_empty_record r = e_a_record r Environment.empty
- * let ez_e_a_empty_record r = ez_e_a_record r Environment.empty
- * let e_a_empty_lambda l i o = e_a_lambda l i o Environment.empty *)
-
-open Environment
-
-let env_sum_type ?(env = empty)
-    ?(type_name = Var.of_name "a_sum_type")
-    (lst : (constructor' * ctor_content) list) =
-  add_type type_name (make_t_ez_sum lst) env
diff --git a/src/stages/4-ast_typed/combinators_environment.mli b/src/stages/4-ast_typed/combinators_environment.mli
deleted file mode 100644
index 9e5e86441..000000000
--- a/src/stages/4-ast_typed/combinators_environment.mli
+++ /dev/null
@@ -1,19 +0,0 @@
-open Types
-
-(* val make_a_e_empty : expression_content -> type_expression -> expression
- * 
- * val e_a_empty_unit : expression
- * val e_a_empty_int : Z.t -> expression
- * val e_a_empty_nat : Z.t -> expression
- * val e_a_empty_mutez : Z.t -> expression
- * val e_a_empty_bool : bool -> expression
- * val e_a_empty_string : ligo_string -> expression
- * val e_a_empty_address : string -> expression
- * val e_a_empty_pair : expression -> expression -> expression
- * val e_a_empty_some : expression -> expression
- * val e_a_empty_none : type_expression -> expression
- * val e_a_empty_record : expression label_map -> expression
- * val ez_e_a_empty_record : ( label * expression ) list -> expression
- * val e_a_empty_lambda : lambda -> type_expression -> type_expression -> expression *)
-
-val env_sum_type : ?env:environment -> ?type_name:type_variable -> (constructor' * ctor_content) list ->  environment
diff --git a/src/stages/4-ast_typed/environment.ml b/src/stages/4-ast_typed/environment.ml
index 30e59ebab..0b9457466 100644
--- a/src/stages/4-ast_typed/environment.ml
+++ b/src/stages/4-ast_typed/environment.ml
@@ -38,6 +38,9 @@ let add_ez_binder : expression_variable -> type_expression -> t -> t = fun k v e
 let add_ez_declaration : expression_variable -> expression -> t -> t = fun k ae e ->
   add_expr k (make_element_declaration e ae) e
 
+let add_ez_sum_type ?(env = empty) ?(type_name = Var.of_name "a_sum_type") (lst : (constructor' * ctor_content) list) =
+  add_type type_name (make_t_ez_sum lst) env
+
 let convert_constructor' (S.Constructor c) = Constructor c
 
 let get_constructor : Ast_core.constructor' -> t -> (type_expression * type_expression) option = fun k x -> (* Left is the constructor, right is the sum type *)
@@ -76,4 +79,4 @@ module PP = struct
       expr_environment (get_expr_environment e)
       type_environment (get_type_environment e)
 
-end
\ No newline at end of file
+end
diff --git a/src/stages/4-ast_typed/environment.mli b/src/stages/4-ast_typed/environment.mli
index 6b3fb52e2..d73279d85 100644
--- a/src/stages/4-ast_typed/environment.mli
+++ b/src/stages/4-ast_typed/environment.mli
@@ -11,6 +11,7 @@ val get_opt : expression_variable -> t -> element option
 val get_type_opt : type_variable -> t -> type_expression option
 val get_constructor : Ast_core.constructor' -> t -> (type_expression * type_expression) option
 
+val add_ez_sum_type : ?env:environment -> ?type_name:type_variable -> (constructor' * ctor_content) list ->  environment
 module PP : sig
   open Format
 
diff --git a/src/stages/4-ast_typed/misc.ml b/src/stages/4-ast_typed/misc.ml
index 81daf803e..7528dab2e 100644
--- a/src/stages/4-ast_typed/misc.ml
+++ b/src/stages/4-ast_typed/misc.ml
@@ -522,11 +522,6 @@ let get_entry (lst : program) (name : string) : expression result =
   in
   List.find_map aux lst
 
-(* let program_environment (program : program) : environment =
- *   let last_declaration = Location.unwrap List.(hd @@ rev program) in
- *   match last_declaration with
- *   | Declaration_constant { binder=_ ; expr=_ ; inline=_ ; post_env } -> post_env *)
-
 let equal_variables a b : bool =
   match a.expression_content, b.expression_content with
   | E_variable a, E_variable b -> Var.equal a b
diff --git a/src/stages/4-ast_typed/misc.mli b/src/stages/4-ast_typed/misc.mli
index c6c18e221..561458303 100644
--- a/src/stages/4-ast_typed/misc.mli
+++ b/src/stages/4-ast_typed/misc.mli
@@ -70,7 +70,6 @@ val assert_literal_eq : ( literal * literal ) -> unit result
 *)
 
 val get_entry : program -> string -> expression result
-(* val program_environment : program -> environment *)
 
 val p_constant : constant_tag -> p_ctor_args -> type_value
 val c_equation : type_value -> type_value -> string -> type_constraint
diff --git a/src/test/typer_tests.ml b/src/test/typer_tests.ml
index e4ea12df5..c26e690ba 100644
--- a/src/test/typer_tests.ml
+++ b/src/test/typer_tests.ml
@@ -34,7 +34,7 @@ module TestExpressions = struct
 
   module I = Simplified.Combinators
   module O = Typed.Combinators
-  module E = O
+  module E = Typed.Environment
 
   let unit   () : unit result = test_expression I.(e_unit ())    O.(t_unit ())
   let int    () : unit result = test_expression I.(e_int (Z.of_int 32))     O.(t_int ())
@@ -59,7 +59,7 @@ module TestExpressions = struct
         (Typed.Constructor "foo", {ctor_type = Typed.t_int () ; michelson_annotation = None ; ctor_decl_pos = 0});
         (Typed.Constructor "bar", {ctor_type = Typed.t_string () ; michelson_annotation = None ; ctor_decl_pos = 1}) ]
     in test_expression
-      ~env:(E.env_sum_type variant_foo_bar)
+      ~env:(E.add_ez_sum_type variant_foo_bar)
       I.(e_constructor "foo" (e_int (Z.of_int 32)))
       O.(make_t_ez_sum variant_foo_bar)