diff --git a/compiler/dcalc/ast.ml b/compiler/dcalc/ast.ml
index ec1544f3..572ed0d3 100644
--- a/compiler/dcalc/ast.ml
+++ b/compiler/dcalc/ast.ml
@@ -32,7 +32,7 @@ module EnumConstructor : Uid.Id with type info = Uid.MarkedString.info =
 
 module EnumMap : Map.S with type key = EnumName.t = Map.Make (EnumName)
 
-type typ_lit = TBool | TUnit | TInt | TRat | TMoney | TDate | TDuration [@@deriving show]
+type typ_lit = TBool | TUnit | TInt | TRat | TMoney | TDate | TDuration
 
 type struct_name = StructName.t
 
@@ -40,12 +40,12 @@ type enum_name = EnumName.t
 
 type typ =
   | TLit of typ_lit
-  | TTuple of typ Pos.marked list * (struct_name[@opaque]) option
-  | TEnum of typ Pos.marked list * (enum_name[@opaque])
+  | TTuple of typ Pos.marked list * (struct_name) option
+  | TEnum of typ Pos.marked list * (enum_name)
   | TArrow of typ Pos.marked * typ Pos.marked
   | TArray of typ Pos.marked
   | TAny
-[@@deriving show]
+
 
 type date = Runtime.date
 
@@ -67,9 +67,9 @@ type lit =
   | LDate of date
   | LDuration of duration
 
-type op_kind = KInt | KRat | KMoney | KDate | KDuration [@@deriving show]
+type op_kind = KInt | KRat | KMoney | KDate | KDuration
 
-type ternop = Fold [@@deriving show]
+type ternop = Fold
 
 type binop =
   | And
@@ -88,39 +88,38 @@ type binop =
   | Map
   | Concat
   | Filter
-[@@deriving show]
 
-type log_entry = VarDef of typ | BeginCall | EndCall | PosRecordIfTrueBool [@@deriving show]
+type log_entry = VarDef of typ | BeginCall | EndCall | PosRecordIfTrueBool
 
 type unop =
   | Not
   | Minus of op_kind
-  | Log of log_entry * (Utils.Uid.MarkedString.info list[@opaque])
+  | Log of log_entry * (Utils.Uid.MarkedString.info list)
   | Length
   | IntToRat
   | GetDay
   | GetMonth
   | GetYear
-[@@deriving show]
 
-type operator = Ternop of ternop | Binop of binop | Unop of unop [@@deriving show]
+
+type operator = Ternop of ternop | Binop of binop | Unop of unop
 
 type expr =
-  | EVar of (expr Bindlib.var[@opaque]) Pos.marked
-  | ETuple of expr Pos.marked list * (struct_name[@opaque]) option
-  | ETupleAccess of expr Pos.marked * int * (struct_name[@opaque]) option * typ Pos.marked list
-  | EInj of expr Pos.marked * int * (enum_name[@opaque]) * typ Pos.marked list
-  | EMatch of expr Pos.marked * expr Pos.marked list * (enum_name[@opaque])
+  | EVar of (expr Bindlib.var) Pos.marked
+  | ETuple of expr Pos.marked list * (struct_name) option
+  | ETupleAccess of expr Pos.marked * int * (struct_name) option * typ Pos.marked list
+  | EInj of expr Pos.marked * int * (enum_name) * typ Pos.marked list
+  | EMatch of expr Pos.marked * expr Pos.marked list * (enum_name)
   | EArray of expr Pos.marked list
-  | ELit of (lit[@opaque])
-  | EAbs of ((expr, expr Pos.marked) Bindlib.mbinder[@opaque]) Pos.marked * typ Pos.marked list
+  | ELit of (lit)
+  | EAbs of ((expr, expr Pos.marked) Bindlib.mbinder) Pos.marked * typ Pos.marked list
   | EApp of expr Pos.marked * expr Pos.marked list
   | EAssert of expr Pos.marked
   | EOp of operator
   | EDefault of expr Pos.marked list * expr Pos.marked * expr Pos.marked
   | EIfThenElse of expr Pos.marked * expr Pos.marked * expr Pos.marked
   | ErrorOnEmpty of expr Pos.marked
-[@@deriving show]
+
 
 type struct_ctx = (StructFieldName.t * typ Pos.marked) list StructMap.t
 
diff --git a/compiler/dcalc/ast.mli b/compiler/dcalc/ast.mli
index 0a454710..f18731b7 100644
--- a/compiler/dcalc/ast.mli
+++ b/compiler/dcalc/ast.mli
@@ -32,7 +32,7 @@ module EnumMap : Map.S with type key = EnumName.t
 
 (** {1 Abstract syntax tree} *)
 
-type typ_lit = TBool | TUnit | TInt | TRat | TMoney | TDate | TDuration [@@deriving show]
+type typ_lit = TBool | TUnit | TInt | TRat | TMoney | TDate | TDuration
 
 type typ =
   | TLit of typ_lit
@@ -41,7 +41,7 @@ type typ =
   | TArrow of typ Pos.marked * typ Pos.marked
   | TArray of typ Pos.marked
   | TAny
-[@@deriving show]
+
 
 type date = Runtime.date
 
@@ -102,7 +102,7 @@ type unop =
   | GetMonth
   | GetYear
 
-type operator = Ternop of ternop | Binop of binop | Unop of unop [@@deriving show]
+type operator = Ternop of ternop | Binop of binop | Unop of unop
 
 (** The expressions use the {{:https://lepigre.fr/ocaml-bindlib/} Bindlib} library, based on
     higher-order abstract syntax*)
@@ -125,7 +125,7 @@ type expr =
   | EDefault of expr Pos.marked list * expr Pos.marked * expr Pos.marked
   | EIfThenElse of expr Pos.marked * expr Pos.marked * expr Pos.marked
   | ErrorOnEmpty of expr Pos.marked
-[@@deriving show]
+
 
 type struct_ctx = (StructFieldName.t * typ Pos.marked) list StructMap.t
 
diff --git a/compiler/lcalc/ast.mli b/compiler/lcalc/ast.mli
index 15350081..f16f6b15 100644
--- a/compiler/lcalc/ast.mli
+++ b/compiler/lcalc/ast.mli
@@ -107,7 +107,7 @@ val make_some : expr Pos.marked Bindlib.box -> expr Pos.marked Bindlib.box
 
 val make_some' : expr Pos.marked -> expr
 
-val make_matchopt_dumb :
+val make_matchopt_with_abs_arms :
   expr Pos.marked Bindlib.box ->
   expr Pos.marked Bindlib.box ->
   expr Pos.marked Bindlib.box ->