diff --git a/src/passes/4-typer-new/typer.ml b/src/passes/4-typer-new/typer.ml
index ba9e10bd0..7eb46e26e 100644
--- a/src/passes/4-typer-new/typer.ml
+++ b/src/passes/4-typer-new/typer.ml
@@ -897,7 +897,8 @@ and type_expression : environment -> Solver.state -> ?tv_opt:O.type_value -> I.e
 
   | E_constant (name, lst) ->
     let () = ignore (name , lst) in
-    Pervasives.failwith "TODO: E_constant"
+    let _t = Operators.Typer.Operators_types.constant_type name in
+    Pervasives.failwith (Format.asprintf "TODO: E_constant (%a(%a))" Stage_common.PP.constant name (Format.pp_print_list Ast_simplified.PP.expression) lst)
       (*
       let%bind lst' = bind_list @@ List.map (type_expression e) lst in
       let tv_lst = List.map get_type_annotation lst' in
diff --git a/src/passes/operators/operators.ml b/src/passes/operators/operators.ml
index 6c8c92112..4c0d3dbb9 100644
--- a/src/passes/operators/operators.ml
+++ b/src/passes/operators/operators.ml
@@ -365,6 +365,93 @@ module Typer = struct
     let t_set_add      = forall "a" @@ fun a -> a --> set a --> set a
     let t_set_remove   = forall "a" @@ fun a -> a --> set a --> set a
     let t_not          = bool --> bool
+
+    let constant_type : constant -> Typesystem.Core.type_value result = function
+      | C_INT                 -> ok @@ t_int ;
+      | C_UNIT                -> ok @@ t_unit ;
+      | C_NOW                 -> ok @@ t_now ;
+      | C_IS_NAT              -> ok @@ failwith "t_is_nat" ;
+      | C_SOME                -> ok @@ t_some ;
+      | C_NONE                -> ok @@ t_none ;
+      | C_ASSERTION           -> ok @@ t_assertion ;
+      | C_FAILWITH            -> ok @@ t_failwith ;
+      (* LOOPS *)
+      | C_FOLD_WHILE          -> ok @@ failwith "t_fold_while" ;
+      | C_CONTINUE            -> ok @@ failwith "t_continue" ;
+      | C_STOP                -> ok @@ failwith "t_stop" ;
+      (* MATH *)
+      | C_NEG                 -> ok @@ failwith "t_neg" ;
+      | C_ABS                 -> ok @@ t_abs ;
+      | C_ADD                 -> ok @@ t_add ;
+      | C_SUB                 -> ok @@ t_sub ;
+      | C_MUL                 -> ok @@ t_times;
+      | C_DIV                 -> ok @@ t_div ;
+      | C_MOD                 -> ok @@ t_mod ;
+      (* LOGIC *)
+      | C_NOT                 -> ok @@ t_not ;
+      | C_AND                 -> ok @@ failwith "t_and" ;
+      | C_OR                  -> ok @@ failwith "t_or" ;
+      | C_XOR                 -> ok @@ failwith "t_xor" ;
+      (* COMPARATOR *)
+      | C_EQ                  -> ok @@ failwith "t_comparator EQ" ;
+      | C_NEQ                 -> ok @@ failwith "t_comparator NEQ" ;
+      | C_LT                  -> ok @@ failwith "t_comparator LT" ;
+      | C_GT                  -> ok @@ failwith "t_comparator GT" ;
+      | C_LE                  -> ok @@ failwith "t_comparator LE" ;
+      | C_GE                  -> ok @@ failwith "t_comparator GE" ;
+      (* BYTES / STRING *)
+      | C_SIZE                -> ok @@ t_size ;
+      | C_CONCAT              -> ok @@ failwith "t_concat" ;
+      | C_SLICE               -> ok @@ t_slice ;
+      | C_BYTES_PACK          -> ok @@ t_bytes_pack ;
+      | C_BYTES_UNPACK        -> ok @@ t_bytes_unpack ;
+      | C_CONS                -> ok @@ t_cons ;
+      (* SET  *)
+      | C_SET_EMPTY           -> ok @@ failwith "t_set_empty" ;
+      | C_SET_ADD             -> ok @@ t_set_add ;
+      | C_SET_REMOVE          -> ok @@ t_set_remove ;
+      | C_SET_ITER            -> ok @@ failwith "t_set_iter" ;
+      | C_SET_FOLD            -> ok @@ failwith "t_set_fold" ;
+      | C_SET_MEM             -> ok @@ t_set_mem ;
+
+      (* LIST *)
+      | C_LIST_ITER           -> ok @@ failwith "t_list_iter" ;
+      | C_LIST_MAP            -> ok @@ failwith "t_list_map" ;
+      | C_LIST_FOLD           -> ok @@ failwith "t_list_fold" ;
+      | C_LIST_CONS           -> ok @@ failwith "t_list_cons" ;
+      (* MAP *)
+      | C_MAP_GET             -> ok @@ failwith "t_map_get" ;
+      | C_MAP_GET_FORCE       -> ok @@ failwith "t_map_get_force" ;
+      | C_MAP_ADD             -> ok @@ t_map_add ;
+      | C_MAP_REMOVE          -> ok @@ t_map_remove ;
+      | C_MAP_UPDATE          -> ok @@ t_map_update ;
+      | C_MAP_ITER            -> ok @@ t_map_iter ;
+      | C_MAP_MAP             -> ok @@ t_map_map ;
+      | C_MAP_FOLD            -> ok @@ t_map_fold ;
+      | C_MAP_MEM             -> ok @@ t_map_mem ;
+      | C_MAP_FIND            -> ok @@ t_map_find ;
+      | C_MAP_FIND_OPT        -> ok @@ t_map_find_opt ;
+      (* BIG MAP *)
+      (* CRYPTO *)
+      | C_SHA256              -> ok @@ t_hash256 ;
+      | C_SHA512              -> ok @@ t_hash512 ;
+      | C_BLAKE2b             -> ok @@ t_blake2b ;
+      | C_HASH_KEY            -> ok @@ t_hash_key ;
+      | C_CHECK_SIGNATURE     -> ok @@ t_check_signature ;
+      | C_CHAIN_ID            -> ok @@ failwith "t_chain_id" ;
+      (*BLOCKCHAIN *)
+      | C_CONTRACT            -> ok @@ t_get_contract ;
+      | C_CONTRACT_ENTRYPOINT -> ok @@ failwith "t_get_entrypoint" ;
+      | C_AMOUNT              -> ok @@ t_amount ;
+      | C_BALANCE             -> ok @@ failwith "t_balance" ;
+      | C_CALL                -> ok @@ t_transaction ;
+      | C_SENDER              -> ok @@ t_sender ;
+      | C_SOURCE              -> ok @@ t_source ;
+      | C_ADDRESS             -> ok @@ t_address ;
+      | C_SELF_ADDRESS        -> ok @@ failwith "t_self_address";
+      | C_IMPLICIT_ACCOUNT    -> ok @@ failwith "t_implicit_account";
+      | C_SET_DELEGATE        -> ok @@ failwith "t_set_delegate" ;
+      | c                     -> simple_fail @@ Format.asprintf "Typer not implemented for consant %a" Stage_common.PP.constant c
   end
 
   let none = typer_0 "NONE" @@ fun tv_opt ->
diff --git a/src/passes/operators/operators.mli b/src/passes/operators/operators.mli
index 0085f5883..3da294664 100644
--- a/src/passes/operators/operators.mli
+++ b/src/passes/operators/operators.mli
@@ -94,6 +94,7 @@ module Typer : sig
       val t_set_add : Typesystem.Core.type_value
       val t_set_remove : Typesystem.Core.type_value
       val t_not : Typesystem.Core.type_value
+      val constant_type : constant -> Typesystem.Core.type_value Trace.result
     end
 
   (*