replace let _ by let () or add type annotation

compiler/catala.ml

@@ -14,4 +14,4 @@
    License for the specific language governing permissions and limitations under
    the License. *)
 
-let _ = Driver.main ()
+let () = Driver.main ()

compiler/catala_web_interpreter.ml

@@ -2,7 +2,7 @@ open Catala_utils
 open Driver
 open Js_of_ocaml
 
-let _ =
+let () =
   Js.export_all
     (object%js
        method interpret

compiler/dcalc/invariants.ml

@@ -26,7 +26,6 @@ let check_invariant (inv : string * invariant_expr) (p : typed program) : bool =
      reference *)
   let result = ref true in
   let name, inv = inv in
-  let _ = name in
   let total = ref 0 in
   let ok = ref 0 in
   let p' =

compiler/lcalc/to_ocaml.ml

@@ -630,7 +630,7 @@ let format_scope_exec
        for a main scope at the moment."
       scope_name_str;
   Format.pp_open_vbox fmt 2;
-  Format.pp_print_string fmt "let _ =";
+  Format.pp_print_string fmt "let () =";
   (* TODO: dump the output using yojson that should be already available from
      the runtime *)
   Format.pp_print_space fmt ();

compiler/plugins/api_web.ml

@@ -414,7 +414,7 @@ module To_jsoo = struct
        %a@\n\
        %a@\n\
        @\n\
-       @[<v 2>let _ =@ @[<hov 2> Js.export \"%a\"@\n\
+       @[<v 2>let () =@ @[<hov 2> Js.export \"%a\"@\n\
        @[<v 2>(object%%js@ %a@]@\n\
        end)@]@]@?"
       (Option.fold ~none:"" ~some:(fun name -> name) module_name)

compiler/shared_ast/definitions.ml

@@ -604,7 +604,7 @@ type scope_let_kind =
           subscope variables. *)
   | CallingSubScope  (** [let result = s ({ x = s.x; y = s.x; ...}) ]*)
   | DestructuringSubScopeResults  (** [let s.x = result.x ]**)
-  | Assertion  (** [let _ = assert e]*)
+  | Assertion  (** [let () = assert e]*)
 
 type 'e scope_let = {
   scope_let_kind : scope_let_kind;

compiler/shared_ast/optimizations.ml

@@ -228,7 +228,7 @@ let rec optimize_expr :
         (* at this point we know a conflict error will be triggered so we just
            feed the expression to the interpreter that will print the beautiful
            right error message *)
-        let _ = Interpreter.evaluate_expr ctx.decl_ctx e in
+        let (_ : _ gexpr) = Interpreter.evaluate_expr ctx.decl_ctx e in
         assert false
       else
         match excepts, just with

compiler/tests.ml

@@ -1,4 +1,4 @@
-let _ =
+let () =
   let open Alcotest in
   run "Optimizations"
     [

french_law/catala_legifrance/catala_legifrance.ml

@@ -298,7 +298,7 @@ let driver file debug diff expiration custom_date client_id client_secret =
     -1
 
 (** Hook for the executable *)
-let _ =
+let () =
   Stdlib.exit
   @@ Cmdliner.Cmd.eval' ~catch:false
        (Cmdliner.Cmd.v Legifrance_cli.info

french_law/ocaml/api_web.ml

@@ -23,7 +23,7 @@ module AF_web = Allocations_familiales_api_web
 module AL = Aides_logement
 module AL_web = Aides_logement_api_web
 
-let _ =
+let () =
   Js.export_all
     (object%js
        val eventsManager = event_manager

french_law/ocaml/bench.ml

@@ -228,19 +228,19 @@ let run_test_aides_logement () =
   | Runtime.AssertionFailed _ -> ()
 
 let _test =
-  let _ = run_test_aides_logement () in
+  let () = run_test_aides_logement () in
   let raw_events = Runtime.retrieve_log () in
   Runtime.EventParser.parse_raw_events raw_events
 
 let _test =
-  let _ = run_test_allocations_familiales () in
+  let () = run_test_allocations_familiales () in
   let raw_events = Runtime.retrieve_log () in
   Runtime.EventParser.parse_raw_events raw_events
 
 let _bench =
   Random.init (int_of_float (Unix.time ()));
   let num_iter = 10000 in
-  let _ =
+  let (_ : Benchmark.samples) =
     Benchmark.latency1 ~style:Auto ~name:"Allocations familiales"
       (Int64.of_int num_iter) run_test_allocations_familiales ()
   in
@@ -254,7 +254,7 @@ let _bench =
        100.)
     !total_amount
     (Float.div !total_amount (float_of_int !num_successful));
-  let _ =
+  let (_ : Benchmark.samples) =
     Benchmark.latency1 ~style:Auto ~name:"Aides au logement"
       (Int64.of_int num_iter) run_test_aides_logement ()
   in

french_law/ocaml/law_source/unit_tests/run_tests.ml

@@ -8,7 +8,7 @@ let try_test msg test =
     failure := true;
     Format.printf "@{<red>FAIL@} @{<magenta>%s@}\n" msg
 
-let _ =
+let () =
   try_test "Allocations familiales #1" Tests_allocations_familiales.test1;
   try_test "Allocations familiales #2" Tests_allocations_familiales.test2;
   try_test "Allocations familiales #3" Tests_allocations_familiales.test3;