diff --git a/flap/src/hopix/hopixTypechecker.ml b/flap/src/hopix/hopixTypechecker.ml
index b7fd253..061ab25 100644
--- a/flap/src/hopix/hopixTypechecker.ml
+++ b/flap/src/hopix/hopixTypechecker.ml
@@ -157,7 +157,14 @@ and synth_tuple
 and synth_sequence
   : HopixTypes.typing_environment -> expression Position.located list -> HopixTypes.aty
   =
-  fun tenv elist -> failwith "Students! This is your job! (synth_sequence)"
+  fun tenv elist ->
+  match elist with
+  | [] -> failwith "erreur sequence"
+  | [ x ] -> synth_expression tenv x
+  | x :: l ->
+    let x_type = synth_expression tenv x in
+    check_equal_types x.position HopixTypes.hunit x_type;
+    synth_sequence tenv l
 
 and synth_define
   :  HopixTypes.typing_environment -> value_definition -> expression Position.located