Source file desugaring.ml

(* This file is part of the Catala compiler, a specification language for tax and social benefits
   computation rules. Copyright (C) 2020 Inria, contributor: Nicolas Chataing
   <nicolas.chataing@ens.fr> Denis Merigoux <denis.merigoux@inria.fr>

   Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
   in compliance with the License. You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software distributed under the License
   is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   or implied. See the License for the specific language governing permissions and limitations under
   the License. *)

(** Translation from {!module: Surface.Ast} to {!module: Desugaring.Ast}.

    - Removes syntactic sugars
    - Separate code from legislation *)

open Utils

(** {1 Translating expressions} *)

let translate_op_kind (k : Ast.op_kind) : Dcalc.Ast.op_kind =
  match k with
  | KInt -> KInt
  | KDec -> KRat
  | KMoney -> KMoney
  | KDate -> KDate
  | KDuration -> KDuration

let translate_binop (op : Ast.binop) : Dcalc.Ast.binop =
  match op with
  | And -> And
  | Or -> Or
  | Add l -> Add (translate_op_kind l)
  | Sub l -> Sub (translate_op_kind l)
  | Mult l -> Mult (translate_op_kind l)
  | Div l -> Div (translate_op_kind l)
  | Lt l -> Lt (translate_op_kind l)
  | Lte l -> Lte (translate_op_kind l)
  | Gt l -> Gt (translate_op_kind l)
  | Gte l -> Gte (translate_op_kind l)
  | Eq -> Eq
  | Neq -> Neq

let translate_unop (op : Ast.unop) : Dcalc.Ast.unop =
  match op with Not -> Not | Minus l -> Minus (translate_op_kind l)

(** The two modules below help performing operations on map with the {!type: Bindlib.box}. Indeed,
    Catala uses the {{:https://lepigre.fr/ocaml-bindlib/} Bindlib} library to represent bound
    variables in the AST. In this translation, bound variables are used to represent function
    parameters or pattern macthing bindings. *)

module LiftStructFieldMap = Bindlib.Lift (Scopelang.Ast.StructFieldMap)
module LiftEnumConstructorMap = Bindlib.Lift (Scopelang.Ast.EnumConstructorMap)

let disambiguate_constructor (ctxt : Name_resolution.context)
    (constructor : (string Pos.marked option * string Pos.marked) list) (pos : Pos.t) :
    Scopelang.Ast.EnumName.t * Scopelang.Ast.EnumConstructor.t =
  let enum, constructor =
    match constructor with
    | [ c ] -> c
    | _ ->
        Errors.raise_spanned_error "The deep pattern matching syntactic sugar is not yet supported"
          pos
  in
  let possible_c_uids =
    try Desugared.Ast.IdentMap.find (Pos.unmark constructor) ctxt.constructor_idmap
    with Not_found ->
      Errors.raise_spanned_error
        "The name of this constructor has not been defined before, maybe it is a typo?"
        (Pos.get_position constructor)
  in
  match enum with
  | None ->
      if Scopelang.Ast.EnumMap.cardinal possible_c_uids > 1 then
        Errors.raise_spanned_error
          (Format.asprintf
             "This constructor name is ambiguous, it can belong to %a. Disambiguate it by \
              prefixing it with the enum name."
             (Format.pp_print_list
                ~pp_sep:(fun fmt () -> Format.fprintf fmt " or ")
                (fun fmt (s_name, _) ->
                  Format.fprintf fmt "%a" Scopelang.Ast.EnumName.format_t s_name))
             (Scopelang.Ast.EnumMap.bindings possible_c_uids))
          (Pos.get_position constructor);
      Scopelang.Ast.EnumMap.choose possible_c_uids
  | Some enum -> (
      try
        (* The path is fully qualified *)
        let e_uid = Desugared.Ast.IdentMap.find (Pos.unmark enum) ctxt.enum_idmap in
        try
          let c_uid = Scopelang.Ast.EnumMap.find e_uid possible_c_uids in
          (e_uid, c_uid)
        with Not_found ->
          Errors.raise_spanned_error
            (Format.asprintf "Enum %s does not contain case %s" (Pos.unmark enum)
               (Pos.unmark constructor))
            pos
      with Not_found ->
        Errors.raise_spanned_error
          (Format.asprintf "Enum %s has not been defined before" (Pos.unmark enum))
          (Pos.get_position enum) )

(** Usage: [translate_expr scope ctxt expr]

    Translates [expr] into its desugared equivalent. [scope] is used to disambiguate the scope and
    subscopes variables than occur in the expresion *)
let rec translate_expr (scope : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    ((expr, pos) : Ast.expression Pos.marked) : Scopelang.Ast.expr Pos.marked Bindlib.box =
  let scope_ctxt = Scopelang.Ast.ScopeMap.find scope ctxt.scopes in
  let rec_helper = translate_expr scope ctxt in
  match expr with
  | Binop
      ( (Ast.And, _pos_op),
        (TestMatchCase (e1_sub, ((constructors, Some binding), pos_pattern)), _pos_e1),
        e2 ) ->
      (* This sugar corresponds to [e is P x && e'] and should desugar to [match e with P x -> e' |
         _ -> false] *)
      let enum_uid, c_uid = disambiguate_constructor ctxt constructors pos_pattern in
      let cases =
        Scopelang.Ast.EnumConstructorMap.mapi
          (fun c_uid' tau ->
            if Scopelang.Ast.EnumConstructor.compare c_uid c_uid' <> 0 then
              let nop_var = Scopelang.Ast.Var.make ("_", pos) in
              Bindlib.unbox
                (Scopelang.Ast.make_abs [| nop_var |]
                   (Bindlib.box (Scopelang.Ast.ELit (Dcalc.Ast.LBool false), pos))
                   pos [ tau ] pos)
            else
              let ctxt, binding_var = Name_resolution.add_def_local_var ctxt binding in
              let e2 = translate_expr scope ctxt e2 in
              Bindlib.unbox (Scopelang.Ast.make_abs [| binding_var |] e2 pos [ tau ] pos))
          (Scopelang.Ast.EnumMap.find enum_uid ctxt.enums)
      in
      Bindlib.box_apply
        (fun e1_sub -> (Scopelang.Ast.EMatch (e1_sub, enum_uid, cases), pos))
        (translate_expr scope ctxt e1_sub)
  | IfThenElse (e_if, e_then, e_else) ->
      Bindlib.box_apply3
        (fun e_if e_then e_else -> (Scopelang.Ast.EIfThenElse (e_if, e_then, e_else), pos))
        (rec_helper e_if) (rec_helper e_then) (rec_helper e_else)
  | Binop (op, e1, e2) ->
      let op_term =
        Pos.same_pos_as (Scopelang.Ast.EOp (Dcalc.Ast.Binop (translate_binop (Pos.unmark op)))) op
      in
      Bindlib.box_apply2
        (fun e1 e2 -> (Scopelang.Ast.EApp (op_term, [ e1; e2 ]), pos))
        (rec_helper e1) (rec_helper e2)
  | Unop (op, e) ->
      let op_term =
        Pos.same_pos_as (Scopelang.Ast.EOp (Dcalc.Ast.Unop (translate_unop (Pos.unmark op)))) op
      in
      Bindlib.box_apply (fun e -> (Scopelang.Ast.EApp (op_term, [ e ]), pos)) (rec_helper e)
  | Literal l ->
      let untyped_term =
        match l with
        | LNumber ((Int i, _), None) -> Scopelang.Ast.ELit (Dcalc.Ast.LInt i)
        | LNumber ((Int i, _), Some (Percent, _)) ->
            Scopelang.Ast.ELit
              (Dcalc.Ast.LRat Runtime.(decimal_of_integer i /& decimal_of_string "100"))
        | LNumber ((Dec (i, f), _), None) ->
            let digits_f =
              try int_of_float (ceil (float_of_int (Runtime.integer_log2 f) *. log 2.0 /. log 10.0))
              with Invalid_argument _ -> 0
            in
            Scopelang.Ast.ELit
              (Dcalc.Ast.LRat
                 Runtime.(
                   decimal_of_integer i
                   +& decimal_of_integer f
                      /& decimal_of_integer (integer_exponentiation (integer_of_int 10) digits_f)))
        | LNumber ((Dec (i, f), _), Some (Percent, _)) ->
            let digits_f =
              try int_of_float (ceil (float_of_int (Runtime.integer_log2 f) *. log 2.0 /. log 10.0))
              with Invalid_argument _ -> 0
            in
            Scopelang.Ast.ELit
              (Dcalc.Ast.LRat
                 Runtime.(
                   ( decimal_of_integer i
                   +& decimal_of_integer f
                      /& decimal_of_integer (integer_exponentiation (integer_of_int 10) digits_f) )
                   /& decimal_of_string "100"))
        | LBool b -> Scopelang.Ast.ELit (Dcalc.Ast.LBool b)
        | LMoneyAmount i ->
            Scopelang.Ast.ELit
              (Dcalc.Ast.LMoney
                 Runtime.(
                   money_of_cents_integer
                     ((i.money_amount_units *! integer_of_int 100) +! i.money_amount_cents)))
        | LNumber ((Int i, _), Some (Year, _)) ->
            Scopelang.Ast.ELit
              (Dcalc.Ast.LDuration (Runtime.duration_of_numbers (Runtime.integer_to_int i) 0 0))
        | LNumber ((Int i, _), Some (Month, _)) ->
            Scopelang.Ast.ELit
              (Dcalc.Ast.LDuration (Runtime.duration_of_numbers 0 (Runtime.integer_to_int i) 0))
        | LNumber ((Int i, _), Some (Day, _)) ->
            Scopelang.Ast.ELit
              (Dcalc.Ast.LDuration (Runtime.duration_of_numbers 0 0 (Runtime.integer_to_int i)))
        | LNumber ((Dec (_, _), _), Some ((Year | Month | Day), _)) ->
            Errors.raise_spanned_error
              "Impossible to specify decimal amounts of days, months or years" pos
        | LDate date ->
            if Pos.unmark date.literal_date_month > 12 then
              Errors.raise_spanned_error "Month number bigger than 12"
                (Pos.get_position date.literal_date_month);
            if Pos.unmark date.literal_date_day > 31 then
              Errors.raise_spanned_error "Month number bigger than 31"
                (Pos.get_position date.literal_date_day);
            Scopelang.Ast.ELit
              (Dcalc.Ast.LDate
                 ( try
                     Runtime.date_of_numbers
                       (Pos.unmark date.literal_date_year)
                       (Pos.unmark date.literal_date_month)
                       (Pos.unmark date.literal_date_day)
                   with Runtime.ImpossibleDate -> Errors.raise_spanned_error "Invalid date" pos ))
      in
      Bindlib.box (untyped_term, pos)
  | Ident x -> (
      (* first we check whether this is a local var, then we resort to scope-wide variables *)
      match Desugared.Ast.IdentMap.find_opt x ctxt.local_var_idmap with
      | None -> (
          match Desugared.Ast.IdentMap.find_opt x scope_ctxt.var_idmap with
          | Some uid -> Bindlib.box (Scopelang.Ast.ELocation (ScopeVar (uid, pos)), pos)
          | None ->
              Name_resolution.raise_unknown_identifier "for a local or scope-wide variable" (x, pos)
          )
      | Some uid ->
          Scopelang.Ast.make_var (uid, pos) (* the whole box thing is to accomodate for this case *)
      )
  | Dotted (e, c, x) -> (
      match Pos.unmark e with
      | Ident y when Name_resolution.is_subscope_uid scope ctxt y ->
          (* In this case, y.x is a subscope variable *)
          let subscope_uid : Scopelang.Ast.SubScopeName.t =
            Name_resolution.get_subscope_uid scope ctxt (Pos.same_pos_as y e)
          in
          let subscope_real_uid : Scopelang.Ast.ScopeName.t =
            Scopelang.Ast.SubScopeMap.find subscope_uid scope_ctxt.sub_scopes
          in
          let subscope_var_uid = Name_resolution.get_var_uid subscope_real_uid ctxt x in
          Bindlib.box
            ( Scopelang.Ast.ELocation
                (SubScopeVar (subscope_real_uid, (subscope_uid, pos), (subscope_var_uid, pos))),
              pos )
      | _ -> (
          (* In this case e.x is the struct field x access of expression e *)
          let e = translate_expr scope ctxt e in
          let x_possible_structs =
            try Desugared.Ast.IdentMap.find (Pos.unmark x) ctxt.field_idmap
            with Not_found ->
              Errors.raise_spanned_error "Unknown subscope or struct field name"
                (Pos.get_position x)
          in
          match c with
          | None ->
              (* No constructor name was specified *)
              if Scopelang.Ast.StructMap.cardinal x_possible_structs > 1 then
                Errors.raise_spanned_error
                  (Format.asprintf
                     "This struct field name is ambiguous, it can belong to %a. Disambiguate it by \
                      prefixing it with the struct name."
                     (Format.pp_print_list
                        ~pp_sep:(fun fmt () -> Format.fprintf fmt " or ")
                        (fun fmt (s_name, _) ->
                          Format.fprintf fmt "%a" Scopelang.Ast.StructName.format_t s_name))
                     (Scopelang.Ast.StructMap.bindings x_possible_structs))
                  (Pos.get_position x)
              else
                let s_uid, f_uid = Scopelang.Ast.StructMap.choose x_possible_structs in
                Bindlib.box_apply (fun e -> (Scopelang.Ast.EStructAccess (e, f_uid, s_uid), pos)) e
          | Some c_name -> (
              try
                let c_uid = Desugared.Ast.IdentMap.find (Pos.unmark c_name) ctxt.struct_idmap in
                try
                  let f_uid = Scopelang.Ast.StructMap.find c_uid x_possible_structs in
                  Bindlib.box_apply
                    (fun e -> (Scopelang.Ast.EStructAccess (e, f_uid, c_uid), pos))
                    e
                with Not_found ->
                  Errors.raise_spanned_error
                    (Format.asprintf "Struct %s does not contain field %s" (Pos.unmark c_name)
                       (Pos.unmark x))
                    pos
              with Not_found ->
                Errors.raise_spanned_error
                  (Format.asprintf "Struct %s has not been defined before" (Pos.unmark c_name))
                  (Pos.get_position c_name) ) ) )
  | FunCall (f, arg) ->
      Bindlib.box_apply2
        (fun f arg -> (Scopelang.Ast.EApp (f, [ arg ]), pos))
        (rec_helper f) (rec_helper arg)
  | StructLit (s_name, fields) ->
      let s_uid =
        try Desugared.Ast.IdentMap.find (Pos.unmark s_name) ctxt.struct_idmap
        with Not_found ->
          Errors.raise_spanned_error "This identifier should refer to a struct name"
            (Pos.get_position s_name)
      in
      let s_fields =
        List.fold_left
          (fun s_fields (f_name, f_e) ->
            let f_uid =
              try
                Scopelang.Ast.StructMap.find s_uid
                  (Desugared.Ast.IdentMap.find (Pos.unmark f_name) ctxt.field_idmap)
              with Not_found ->
                Errors.raise_spanned_error
                  (Format.asprintf "This identifier should refer to a field of struct %s"
                     (Pos.unmark s_name))
                  (Pos.get_position f_name)
            in
            ( match Scopelang.Ast.StructFieldMap.find_opt f_uid s_fields with
            | None -> ()
            | Some e_field ->
                Errors.raise_multispanned_error
                  (Format.asprintf "The field %a has been defined twice:"
                     Scopelang.Ast.StructFieldName.format_t f_uid)
                  [ (None, Pos.get_position f_e); (None, Pos.get_position (Bindlib.unbox e_field)) ]
            );
            let f_e = translate_expr scope ctxt f_e in
            Scopelang.Ast.StructFieldMap.add f_uid f_e s_fields)
          Scopelang.Ast.StructFieldMap.empty fields
      in
      Bindlib.box_apply
        (fun s_fields -> (Scopelang.Ast.EStruct (s_uid, s_fields), pos))
        (LiftStructFieldMap.lift_box s_fields)
  | EnumInject (enum, constructor, payload) -> (
      let possible_c_uids =
        try Desugared.Ast.IdentMap.find (Pos.unmark constructor) ctxt.constructor_idmap
        with Not_found ->
          Errors.raise_spanned_error
            "The name of this constructor has not been defined before, maybe it is a typo?"
            (Pos.get_position constructor)
      in
      match enum with
      | None ->
          if
            (* No constructor name was specified *)
            Scopelang.Ast.EnumMap.cardinal possible_c_uids > 1
          then
            Errors.raise_spanned_error
              (Format.asprintf
                 "This constructor name is ambiguous, it can belong to %a. Desambiguate it by \
                  prefixing it with the enum name."
                 (Format.pp_print_list
                    ~pp_sep:(fun fmt () -> Format.fprintf fmt " or ")
                    (fun fmt (s_name, _) ->
                      Format.fprintf fmt "%a" Scopelang.Ast.EnumName.format_t s_name))
                 (Scopelang.Ast.EnumMap.bindings possible_c_uids))
              (Pos.get_position constructor)
          else
            let e_uid, c_uid = Scopelang.Ast.EnumMap.choose possible_c_uids in
            let payload = Option.map (translate_expr scope ctxt) payload in
            Bindlib.box_apply
              (fun payload ->
                ( Scopelang.Ast.EEnumInj
                    ( ( match payload with
                      | Some e' -> e'
                      | None -> (Scopelang.Ast.ELit Dcalc.Ast.LUnit, Pos.get_position constructor)
                      ),
                      c_uid,
                      e_uid ),
                  pos ))
              (Bindlib.box_opt payload)
      | Some enum -> (
          try
            (* The path has been fully qualified *)
            let e_uid = Desugared.Ast.IdentMap.find (Pos.unmark enum) ctxt.enum_idmap in
            try
              let c_uid = Scopelang.Ast.EnumMap.find e_uid possible_c_uids in
              let payload = Option.map (translate_expr scope ctxt) payload in
              Bindlib.box_apply
                (fun payload ->
                  ( Scopelang.Ast.EEnumInj
                      ( ( match payload with
                        | Some e' -> e'
                        | None -> (Scopelang.Ast.ELit Dcalc.Ast.LUnit, Pos.get_position constructor)
                        ),
                        c_uid,
                        e_uid ),
                    pos ))
                (Bindlib.box_opt payload)
            with Not_found ->
              Errors.raise_spanned_error
                (Format.asprintf "Enum %s does not contain case %s" (Pos.unmark enum)
                   (Pos.unmark constructor))
                pos
          with Not_found ->
            Errors.raise_spanned_error
              (Format.asprintf "Enum %s has not been defined before" (Pos.unmark enum))
              (Pos.get_position enum) ) )
  | MatchWith (e1, (cases, _cases_pos)) ->
      let e1 = translate_expr scope ctxt e1 in
      let cases_d, e_uid = disambiguate_match_and_build_expression scope ctxt cases in
      Bindlib.box_apply2
        (fun e1 cases_d -> (Scopelang.Ast.EMatch (e1, e_uid, cases_d), pos))
        e1
        (LiftEnumConstructorMap.lift_box cases_d)
  | TestMatchCase (e1, pattern) ->
      ( match snd (Pos.unmark pattern) with
      | None -> ()
      | Some binding ->
          Errors.print_spanned_warning
            "This binding will be ignored (remove it to suppress warning)"
            (Pos.get_position binding) );
      let enum_uid, c_uid =
        disambiguate_constructor ctxt (fst (Pos.unmark pattern)) (Pos.get_position pattern)
      in
      let cases =
        Scopelang.Ast.EnumConstructorMap.mapi
          (fun c_uid' tau ->
            let nop_var = Scopelang.Ast.Var.make ("_", pos) in
            Bindlib.unbox
              (Scopelang.Ast.make_abs [| nop_var |]
                 (Bindlib.box
                    ( Scopelang.Ast.ELit
                        (Dcalc.Ast.LBool (Scopelang.Ast.EnumConstructor.compare c_uid c_uid' = 0)),
                      pos ))
                 pos [ tau ] pos))
          (Scopelang.Ast.EnumMap.find enum_uid ctxt.enums)
      in
      Bindlib.box_apply
        (fun e -> (Scopelang.Ast.EMatch (e, enum_uid, cases), pos))
        (translate_expr scope ctxt e1)
  | ArrayLit es ->
      Bindlib.box_apply
        (fun es -> (Scopelang.Ast.EArray es, pos))
        (Bindlib.box_list (List.map rec_helper es))
  | CollectionOp ((((Ast.Filter | Ast.Map) as op'), _pos_op'), param', collection, predicate) ->
      let collection = rec_helper collection in
      let ctxt, param = Name_resolution.add_def_local_var ctxt param' in
      let f_pred =
        Scopelang.Ast.make_abs [| param |]
          (translate_expr scope ctxt predicate)
          pos [ (Scopelang.Ast.TAny, pos) ] pos
      in
      Bindlib.box_apply2
        (fun f_pred collection ->
          ( Scopelang.Ast.EApp
              ( ( Scopelang.Ast.EOp
                    ( match op' with
                    | Ast.Map -> Dcalc.Ast.Binop Dcalc.Ast.Map
                    | Ast.Filter -> Dcalc.Ast.Binop Dcalc.Ast.Filter
                    | _ -> assert false (* should not happen *) ),
                  pos ),
                [ f_pred; collection ] ),
            pos ))
        f_pred collection
  | CollectionOp
      ( (Ast.Aggregate (Ast.AggregateArgExtremum (max_or_min, pred_typ, init)), pos_op'),
        param',
        collection,
        predicate ) ->
      let init = rec_helper init in
      let collection = rec_helper collection in
      let ctxt, param = Name_resolution.add_def_local_var ctxt param' in
      let op_kind =
        match pred_typ with
        | Ast.Integer -> Dcalc.Ast.KInt
        | Ast.Decimal -> Dcalc.Ast.KRat
        | Ast.Money -> Dcalc.Ast.KMoney
        | Ast.Duration -> Dcalc.Ast.KDuration
        | Ast.Date -> Dcalc.Ast.KDate
        | _ ->
            Errors.raise_spanned_error
              (Format.asprintf "It is impossible to compute the arg-%s of two values of type %a"
                 (if max_or_min then "max" else "min")
                 Print.format_primitive_typ pred_typ)
              pos
      in
      let cmp_op = if max_or_min then Dcalc.Ast.Gt op_kind else Dcalc.Ast.Lt op_kind in
      let f_pred =
        Scopelang.Ast.make_abs [| param |]
          (translate_expr scope ctxt predicate)
          pos [ (Scopelang.Ast.TAny, pos) ] pos
      in
      let f_pred_var = Scopelang.Ast.Var.make ("predicate", Pos.get_position predicate) in
      let f_pred_var_e = Scopelang.Ast.make_var (f_pred_var, Pos.get_position predicate) in
      let acc_var = Scopelang.Ast.Var.make ("acc", pos) in
      let acc_var_e = Scopelang.Ast.make_var (acc_var, pos) in
      let item_var = Scopelang.Ast.Var.make ("item", Pos.get_position (Bindlib.unbox collection)) in
      let item_var_e =
        Scopelang.Ast.make_var (item_var, Pos.get_position (Bindlib.unbox collection))
      in
      let fold_body =
        Bindlib.box_apply3
          (fun acc_var_e item_var_e f_pred_var_e ->
            ( Scopelang.Ast.EIfThenElse
                ( ( Scopelang.Ast.EApp
                      ( (Scopelang.Ast.EOp (Dcalc.Ast.Binop cmp_op), pos_op'),
                        [
                          (Scopelang.Ast.EApp (f_pred_var_e, [ acc_var_e ]), pos);
                          (Scopelang.Ast.EApp (f_pred_var_e, [ item_var_e ]), pos);
                        ] ),
                    pos ),
                  acc_var_e,
                  item_var_e ),
              pos ))
          acc_var_e item_var_e f_pred_var_e
      in
      let fold_f =
        Scopelang.Ast.make_abs [| acc_var; item_var |] fold_body pos
          [ (Scopelang.Ast.TAny, pos); (Scopelang.Ast.TAny, pos) ]
          pos
      in
      let fold =
        Bindlib.box_apply3
          (fun fold_f collection init ->
            ( Scopelang.Ast.EApp
                ( (Scopelang.Ast.EOp (Dcalc.Ast.Ternop Dcalc.Ast.Fold), pos),
                  [ fold_f; init; collection ] ),
              pos ))
          fold_f collection init
      in
      Scopelang.Ast.make_let_in f_pred_var (Scopelang.Ast.TAny, pos) f_pred fold
  | CollectionOp (op', param', collection, predicate) ->
      let ctxt, param = Name_resolution.add_def_local_var ctxt param' in
      let collection = rec_helper collection in
      let init =
        match Pos.unmark op' with
        | Ast.Map | Ast.Filter | Ast.Aggregate (Ast.AggregateArgExtremum _) ->
            assert false (* should not happen *)
        | Ast.Exists ->
            Bindlib.box (Scopelang.Ast.ELit (Dcalc.Ast.LBool false), Pos.get_position op')
        | Ast.Forall -> Bindlib.box (Scopelang.Ast.ELit (Dcalc.Ast.LBool true), Pos.get_position op')
        | Ast.Aggregate (Ast.AggregateSum Ast.Integer) ->
            Bindlib.box
              (Scopelang.Ast.ELit (Dcalc.Ast.LInt (Runtime.integer_of_int 0)), Pos.get_position op')
        | Ast.Aggregate (Ast.AggregateSum Ast.Decimal) ->
            Bindlib.box
              ( Scopelang.Ast.ELit (Dcalc.Ast.LRat (Runtime.decimal_of_string "0")),
                Pos.get_position op' )
        | Ast.Aggregate (Ast.AggregateSum Ast.Money) ->
            Bindlib.box
              ( Scopelang.Ast.ELit
                  (Dcalc.Ast.LMoney (Runtime.money_of_cents_integer (Runtime.integer_of_int 0))),
                Pos.get_position op' )
        | Ast.Aggregate (Ast.AggregateSum Ast.Duration) ->
            Bindlib.box
              ( Scopelang.Ast.ELit (Dcalc.Ast.LDuration (Runtime.duration_of_numbers 0 0 0)),
                Pos.get_position op' )
        | Ast.Aggregate (Ast.AggregateSum t) ->
            Errors.raise_spanned_error
              (Format.asprintf "It is impossible to sum two values of type %a together"
                 Print.format_primitive_typ t)
              pos
        | Ast.Aggregate (Ast.AggregateExtremum (_, _, init)) -> rec_helper init
        | Ast.Aggregate Ast.AggregateCount ->
            Bindlib.box
              (Scopelang.Ast.ELit (Dcalc.Ast.LInt (Runtime.integer_of_int 0)), Pos.get_position op')
      in
      let acc_var = Scopelang.Ast.Var.make ("acc", Pos.get_position param') in
      let acc = Scopelang.Ast.make_var (acc_var, Pos.get_position param') in
      let f_body =
        let make_body (op : Dcalc.Ast.binop) =
          Bindlib.box_apply2
            (fun predicate acc ->
              ( Scopelang.Ast.EApp
                  ( (Scopelang.Ast.EOp (Dcalc.Ast.Binop op), Pos.get_position op'),
                    [ acc; predicate ] ),
                pos ))
            (translate_expr scope ctxt predicate)
            acc
        in
        let make_extr_body (cmp_op : Dcalc.Ast.binop) (t : Scopelang.Ast.typ Pos.marked) =
          let tmp_var = Scopelang.Ast.Var.make ("tmp", Pos.get_position param') in
          let tmp = Scopelang.Ast.make_var (tmp_var, Pos.get_position param') in
          Scopelang.Ast.make_let_in tmp_var t
            (translate_expr scope ctxt predicate)
            (Bindlib.box_apply2
               (fun acc tmp ->
                 ( Scopelang.Ast.EIfThenElse
                     ( ( Scopelang.Ast.EApp
                           ( (Scopelang.Ast.EOp (Dcalc.Ast.Binop cmp_op), Pos.get_position op'),
                             [ acc; tmp ] ),
                         pos ),
                       acc,
                       tmp ),
                   pos ))
               acc tmp)
        in
        match Pos.unmark op' with
        | Ast.Map | Ast.Filter | Ast.Aggregate (Ast.AggregateArgExtremum _) ->
            assert false (* should not happen *)
        | Ast.Exists -> make_body Dcalc.Ast.Or
        | Ast.Forall -> make_body Dcalc.Ast.And
        | Ast.Aggregate (Ast.AggregateSum Ast.Integer) -> make_body (Dcalc.Ast.Add Dcalc.Ast.KInt)
        | Ast.Aggregate (Ast.AggregateSum Ast.Decimal) -> make_body (Dcalc.Ast.Add Dcalc.Ast.KRat)
        | Ast.Aggregate (Ast.AggregateSum Ast.Money) -> make_body (Dcalc.Ast.Add Dcalc.Ast.KMoney)
        | Ast.Aggregate (Ast.AggregateSum Ast.Duration) ->
            make_body (Dcalc.Ast.Add Dcalc.Ast.KDuration)
        | Ast.Aggregate (Ast.AggregateSum _) -> assert false (* should not happen *)
        | Ast.Aggregate (Ast.AggregateExtremum (max_or_min, t, _)) ->
            let op_kind, typ =
              match t with
              | Ast.Integer -> (Dcalc.Ast.KInt, (Scopelang.Ast.TLit TInt, pos))
              | Ast.Decimal -> (Dcalc.Ast.KRat, (Scopelang.Ast.TLit TRat, pos))
              | Ast.Money -> (Dcalc.Ast.KMoney, (Scopelang.Ast.TLit TMoney, pos))
              | Ast.Duration -> (Dcalc.Ast.KDuration, (Scopelang.Ast.TLit TDuration, pos))
              | Ast.Date -> (Dcalc.Ast.KDate, (Scopelang.Ast.TLit TDate, pos))
              | _ ->
                  Errors.raise_spanned_error
                    (Format.asprintf "It is impossible to compute the %s of two values of type %a"
                       (if max_or_min then "max" else "min")
                       Print.format_primitive_typ t)
                    pos
            in
            let cmp_op = if max_or_min then Dcalc.Ast.Gt op_kind else Dcalc.Ast.Lt op_kind in
            make_extr_body cmp_op typ
        | Ast.Aggregate Ast.AggregateCount ->
            Bindlib.box_apply2
              (fun predicate acc ->
                ( Scopelang.Ast.EIfThenElse
                    ( predicate,
                      ( Scopelang.Ast.EApp
                          ( ( Scopelang.Ast.EOp (Dcalc.Ast.Binop (Dcalc.Ast.Add Dcalc.Ast.KInt)),
                              Pos.get_position op' ),
                            [
                              acc;
                              ( Scopelang.Ast.ELit (Dcalc.Ast.LInt (Runtime.integer_of_int 1)),
                                Pos.get_position predicate );
                            ] ),
                        pos ),
                      acc ),
                  pos ))
              (translate_expr scope ctxt predicate)
              acc
      in
      let f =
        let make_f (t : Dcalc.Ast.typ_lit) =
          Bindlib.box_apply
            (fun binder ->
              ( Scopelang.Ast.EAbs
                  ( pos,
                    binder,
                    [
                      (Scopelang.Ast.TLit t, Pos.get_position op');
                      (Scopelang.Ast.TAny, pos)
                      (* we put any here because the type of the elements of the arrays is not
                         always the type of the accumulator; for instance in AggregateCount. *);
                    ] ),
                pos ))
            (Bindlib.bind_mvar [| acc_var; param |] f_body)
        in
        match Pos.unmark op' with
        | Ast.Map | Ast.Filter | Ast.Aggregate (Ast.AggregateArgExtremum _) ->
            assert false (* should not happen *)
        | Ast.Exists -> make_f Dcalc.Ast.TBool
        | Ast.Forall -> make_f Dcalc.Ast.TBool
        | Ast.Aggregate (Ast.AggregateSum Ast.Integer)
        | Ast.Aggregate (Ast.AggregateExtremum (_, Ast.Integer, _)) ->
            make_f Dcalc.Ast.TInt
        | Ast.Aggregate (Ast.AggregateSum Ast.Decimal)
        | Ast.Aggregate (Ast.AggregateExtremum (_, Ast.Decimal, _)) ->
            make_f Dcalc.Ast.TRat
        | Ast.Aggregate (Ast.AggregateSum Ast.Money)
        | Ast.Aggregate (Ast.AggregateExtremum (_, Ast.Money, _)) ->
            make_f Dcalc.Ast.TMoney
        | Ast.Aggregate (Ast.AggregateSum Ast.Duration)
        | Ast.Aggregate (Ast.AggregateExtremum (_, Ast.Duration, _)) ->
            make_f Dcalc.Ast.TDuration
        | Ast.Aggregate (Ast.AggregateSum _) | Ast.Aggregate (Ast.AggregateExtremum _) ->
            assert false (* should not happen *)
        | Ast.Aggregate Ast.AggregateCount -> make_f Dcalc.Ast.TInt
      in
      Bindlib.box_apply3
        (fun f collection init ->
          ( Scopelang.Ast.EApp
              ((Scopelang.Ast.EOp (Dcalc.Ast.Ternop Dcalc.Ast.Fold), pos), [ f; init; collection ]),
            pos ))
        f collection init
  | MemCollection (member, collection) ->
      let param_var = Scopelang.Ast.Var.make ("collection_member", pos) in
      let param = Scopelang.Ast.make_var (param_var, pos) in
      let collection = rec_helper collection in
      let init = Bindlib.box (Scopelang.Ast.ELit (Dcalc.Ast.LBool false), pos) in
      let acc_var = Scopelang.Ast.Var.make ("acc", pos) in
      let acc = Scopelang.Ast.make_var (acc_var, pos) in
      let f_body =
        Bindlib.box_apply3
          (fun member acc param ->
            ( Scopelang.Ast.EApp
                ( (Scopelang.Ast.EOp (Dcalc.Ast.Binop Dcalc.Ast.Or), pos),
                  [
                    ( Scopelang.Ast.EApp
                        ((Scopelang.Ast.EOp (Dcalc.Ast.Binop Dcalc.Ast.Eq), pos), [ member; param ]),
                      pos );
                    acc;
                  ] ),
              pos ))
          (translate_expr scope ctxt member)
          acc param
      in
      let f =
        Bindlib.box_apply
          (fun binder ->
            ( Scopelang.Ast.EAbs
                ( pos,
                  binder,
                  [ (Scopelang.Ast.TLit Dcalc.Ast.TBool, pos); (Scopelang.Ast.TAny, pos) ] ),
              pos ))
          (Bindlib.bind_mvar [| acc_var; param_var |] f_body)
      in
      Bindlib.box_apply3
        (fun f collection init ->
          ( Scopelang.Ast.EApp
              ((Scopelang.Ast.EOp (Dcalc.Ast.Ternop Dcalc.Ast.Fold), pos), [ f; init; collection ]),
            pos ))
        f collection init
  | Builtin IntToDec -> Bindlib.box (Scopelang.Ast.EOp (Dcalc.Ast.Unop Dcalc.Ast.IntToRat), pos)
  | Builtin Cardinal -> Bindlib.box (Scopelang.Ast.EOp (Dcalc.Ast.Unop Dcalc.Ast.Length), pos)
  | Builtin GetDay -> Bindlib.box (Scopelang.Ast.EOp (Dcalc.Ast.Unop Dcalc.Ast.GetDay), pos)
  | Builtin GetMonth -> Bindlib.box (Scopelang.Ast.EOp (Dcalc.Ast.Unop Dcalc.Ast.GetMonth), pos)
  | Builtin GetYear -> Bindlib.box (Scopelang.Ast.EOp (Dcalc.Ast.Unop Dcalc.Ast.GetYear), pos)

and disambiguate_match_and_build_expression (scope : Scopelang.Ast.ScopeName.t)
    (ctxt : Name_resolution.context) (cases : Ast.match_case Pos.marked list) :
    Scopelang.Ast.expr Pos.marked Bindlib.box Scopelang.Ast.EnumConstructorMap.t
    * Scopelang.Ast.EnumName.t =
  let expr, e_name =
    List.fold_left
      (fun (cases_d, e_uid) (case, _pos_case) ->
        let constructor, binding = Pos.unmark case.Ast.match_case_pattern in
        let e_uid', c_uid =
          disambiguate_constructor ctxt constructor (Pos.get_position case.Ast.match_case_pattern)
        in
        let e_uid =
          match e_uid with
          | None -> e_uid'
          | Some e_uid ->
              if e_uid = e_uid' then e_uid
              else
                Errors.raise_spanned_error
                  (Format.asprintf
                     "This case matches a constructor of enumeration %a but previous case were \
                      matching constructors of enumeration %a"
                     Scopelang.Ast.EnumName.format_t e_uid Scopelang.Ast.EnumName.format_t e_uid')
                  (Pos.get_position case.Ast.match_case_pattern)
        in
        ( match Scopelang.Ast.EnumConstructorMap.find_opt c_uid cases_d with
        | None -> ()
        | Some e_case ->
            Errors.raise_multispanned_error
              (Format.asprintf "The constructor %a has been matched twice:"
                 Scopelang.Ast.EnumConstructor.format_t c_uid)
              [
                (None, Pos.get_position case.match_case_expr);
                (None, Pos.get_position (Bindlib.unbox e_case));
              ] );
        let ctxt, (param_var, param_pos) =
          match binding with
          | None -> (ctxt, (Scopelang.Ast.Var.make ("_", Pos.no_pos), Pos.no_pos))
          | Some param ->
              let ctxt, param_var = Name_resolution.add_def_local_var ctxt param in
              (ctxt, (param_var, Pos.get_position param))
        in
        let case_body = translate_expr scope ctxt case.Ast.match_case_expr in
        let e_binder = Bindlib.bind_mvar (Array.of_list [ param_var ]) case_body in
        let case_expr =
          Bindlib.box_apply2
            (fun e_binder case_body ->
              Pos.same_pos_as
                (Scopelang.Ast.EAbs
                   ( param_pos,
                     e_binder,
                     [
                       Scopelang.Ast.EnumConstructorMap.find c_uid
                         (Scopelang.Ast.EnumMap.find e_uid ctxt.Name_resolution.enums);
                     ] ))
                case_body)
            e_binder case_body
        in
        (Scopelang.Ast.EnumConstructorMap.add c_uid case_expr cases_d, Some e_uid))
      (Scopelang.Ast.EnumConstructorMap.empty, None)
      cases
  in
  (expr, Option.get e_name)

(** {1 Translating scope definitions} *)

(** A scope use can be annotated with a pervasive precondition, in which case this precondition has
    to be appended to the justifications of each definition in the subscope use. This is what this
    function does. *)
let merge_conditions (precond : Scopelang.Ast.expr Pos.marked Bindlib.box option)
    (cond : Scopelang.Ast.expr Pos.marked Bindlib.box option) (default_pos : Pos.t) :
    Scopelang.Ast.expr Pos.marked Bindlib.box =
  match (precond, cond) with
  | Some precond, Some cond ->
      let op_term =
        (Scopelang.Ast.EOp (Dcalc.Ast.Binop Dcalc.Ast.And), Pos.get_position (Bindlib.unbox precond))
      in
      Bindlib.box_apply2
        (fun precond cond ->
          (Scopelang.Ast.EApp (op_term, [ precond; cond ]), Pos.get_position precond))
        precond cond
  | Some cond, None | None, Some cond -> cond
  | None, None -> Bindlib.box (Scopelang.Ast.ELit (Dcalc.Ast.LBool true), default_pos)

(** Translates a surface definition into condition into a desugared {!type: Desugared.Ast.rule} *)
let process_default (ctxt : Name_resolution.context) (scope : Scopelang.Ast.ScopeName.t)
    (def_key : Desugared.Ast.ScopeDef.t Pos.marked)
    (param_uid : Scopelang.Ast.Var.t Pos.marked option)
    (precond : Scopelang.Ast.expr Pos.marked Bindlib.box option)
    (exception_to_rule : Desugared.Ast.RuleName.t Pos.marked option)
    (just : Ast.expression Pos.marked option) (cons : Ast.expression Pos.marked) :
    Desugared.Ast.rule =
  let just = match just with Some just -> Some (translate_expr scope ctxt just) | None -> None in
  let just = merge_conditions precond just (Pos.get_position def_key) in
  let cons = translate_expr scope ctxt cons in
  {
    just;
    cons;
    parameter =
      (let def_key_typ = Name_resolution.get_def_typ ctxt (Pos.unmark def_key) in
       match (Pos.unmark def_key_typ, param_uid) with
       | Scopelang.Ast.TArrow (t_in, _), Some param_uid -> Some (Pos.unmark param_uid, t_in)
       | Scopelang.Ast.TArrow _, None ->
           Errors.raise_spanned_error
             "This definition has a function type but the parameter is missing"
             (Pos.get_position (Bindlib.unbox cons))
       | _, Some _ ->
           Errors.raise_spanned_error
             "This definition has a parameter but its type is not a function"
             (Pos.get_position (Bindlib.unbox cons))
       | _ -> None);
    exception_to_rule;
  }

(** Wrapper around {!val: process_default} that performs some name disambiguation *)
let process_def (precond : Scopelang.Ast.expr Pos.marked Bindlib.box option)
    (scope_uid : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    (prgm : Desugared.Ast.program) (def : Ast.definition) : Desugared.Ast.program =
  let scope : Desugared.Ast.scope = Scopelang.Ast.ScopeMap.find scope_uid prgm.program_scopes in
  let scope_ctxt = Scopelang.Ast.ScopeMap.find scope_uid ctxt.scopes in
  let def_key =
    Name_resolution.get_def_key (Pos.unmark def.definition_name) scope_uid ctxt
      (Pos.get_position def.definition_expr)
  in
  (* We add to the name resolution context the name of the parameter variable *)
  let param_uid, new_ctxt =
    match def.definition_parameter with
    | None -> (None, ctxt)
    | Some param ->
        let ctxt, param_var = Name_resolution.add_def_local_var ctxt param in
        (Some (Pos.same_pos_as param_var param), ctxt)
  in
  let scope_updated =
    let x_def, x_type, is_cond =
      match Desugared.Ast.ScopeDefMap.find_opt def_key scope.scope_defs with
      | Some def -> def
      | None ->
          ( Desugared.Ast.RuleMap.empty,
            Name_resolution.get_def_typ ctxt def_key,
            Name_resolution.is_def_cond ctxt def_key )
    in
    let rule_name =
      match def.Ast.definition_label with
      | None -> None
      | Some label -> Some (Desugared.Ast.IdentMap.find (Pos.unmark label) scope_ctxt.label_idmap)
    in
    let rule_name =
      match rule_name with
      | Some x -> x
      | None ->
          Desugared.Ast.RuleName.fresh
            ( match def.definition_label with
            | None ->
                Pos.map_under_mark
                  (fun qident -> String.concat "." (List.map (fun i -> Pos.unmark i) qident))
                  def.definition_name
            | Some label -> label )
    in
    let is_exception (def : Ast.definition) =
      match def.Ast.definition_exception_to with NotAnException -> false | _ -> true
    in
    (* If we had previously defined a rulename for this default definition during the elaboration of
       default exceptions, this trumps the newly generated name. *)
    let rule_name =
      if is_exception def then rule_name
      else
        match Desugared.Ast.ScopeDefMap.find_opt def_key scope_ctxt.default_rulemap with
        | None | Some Name_resolution.Ambiguous -> rule_name
        | Some (Name_resolution.Unique x) -> x
    in
    let parent_rule =
      match def.Ast.definition_exception_to with
      | NotAnException -> None
      | UnlabeledException ->
          Some
            ( match Desugared.Ast.ScopeDefMap.find_opt def_key scope_ctxt.default_rulemap with
            (* This should have been caught previously by check_unlabeled_exception *)
            | None | Some Name_resolution.Ambiguous -> assert false
            | Some (Name_resolution.Unique name) -> Pos.same_pos_as name def.Ast.definition_name )
      | ExceptionToLabel label ->
          Some
            ( try
                Pos.same_pos_as
                  (Desugared.Ast.IdentMap.find (Pos.unmark label) scope_ctxt.label_idmap)
                  label
              with Not_found ->
                Errors.raise_spanned_error
                  (Format.asprintf "Unknown label: \"%s\"" (Pos.unmark label))
                  (Pos.get_position label) )
    in
    let x_def =
      Desugared.Ast.RuleMap.add rule_name
        (process_default new_ctxt scope_uid
           (def_key, Pos.get_position def.definition_name)
           param_uid precond parent_rule def.definition_condition def.definition_expr)
        x_def
    in
    {
      scope with
      scope_defs = Desugared.Ast.ScopeDefMap.add def_key (x_def, x_type, is_cond) scope.scope_defs;
    }
  in
  {
    prgm with
    program_scopes = Scopelang.Ast.ScopeMap.add scope_uid scope_updated prgm.program_scopes;
  }

(** Translates a {!type: Surface.Ast.rule} into the corresponding {!type: Surface.Ast.definition} *)
let rule_to_def (rule : Ast.rule) : Ast.definition =
  let consequence_expr = Ast.Literal (Ast.LBool (Pos.unmark rule.rule_consequence)) in
  {
    Ast.definition_label = rule.rule_label;
    Ast.definition_exception_to = rule.rule_exception_to;
    Ast.definition_name = rule.rule_name;
    Ast.definition_parameter = rule.rule_parameter;
    Ast.definition_condition = rule.rule_condition;
    Ast.definition_expr = (consequence_expr, Pos.get_position rule.rule_consequence);
  }

(** Translates a {!type: Surface.Ast.rule} from the surface language *)
let process_rule (precond : Scopelang.Ast.expr Pos.marked Bindlib.box option)
    (scope : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    (prgm : Desugared.Ast.program) (rule : Ast.rule) : Desugared.Ast.program =
  let def = rule_to_def rule in
  process_def precond scope ctxt prgm def

(** Translates assertions *)
let process_assert (precond : Scopelang.Ast.expr Pos.marked Bindlib.box option)
    (scope_uid : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    (prgm : Desugared.Ast.program) (ass : Ast.assertion) : Desugared.Ast.program =
  let scope : Desugared.Ast.scope = Scopelang.Ast.ScopeMap.find scope_uid prgm.program_scopes in
  let ass =
    translate_expr scope_uid ctxt
      ( match ass.Ast.assertion_condition with
      | None -> ass.Ast.assertion_content
      | Some cond ->
          ( Ast.IfThenElse
              (cond, ass.Ast.assertion_content, Pos.same_pos_as (Ast.Literal (Ast.LBool true)) cond),
            Pos.get_position cond ) )
  in
  let ass =
    match precond with
    | Some precond ->
        Bindlib.box_apply2
          (fun precond ass ->
            ( Scopelang.Ast.EIfThenElse
                (precond, ass, Pos.same_pos_as (Scopelang.Ast.ELit (Dcalc.Ast.LBool true)) precond),
              Pos.get_position precond ))
          precond ass
    | None -> ass
  in
  let new_scope = { scope with scope_assertions = ass :: scope.scope_assertions } in
  { prgm with program_scopes = Scopelang.Ast.ScopeMap.add scope_uid new_scope prgm.program_scopes }

(** Translates a surface definition, rule or assertion *)
let process_scope_use_item (precond : Ast.expression Pos.marked option)
    (scope : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    (prgm : Desugared.Ast.program) (item : Ast.scope_use_item Pos.marked) : Desugared.Ast.program =
  let precond = Option.map (translate_expr scope ctxt) precond in
  match Pos.unmark item with
  | Ast.Rule rule -> process_rule precond scope ctxt prgm rule
  | Ast.Definition def -> process_def precond scope ctxt prgm def
  | Ast.Assertion ass -> process_assert precond scope ctxt prgm ass
  | _ -> prgm

(** {1 Translating top-level items} *)

(* If this is an unlabeled exception, ensures that it has a unique default definition *)
let check_unlabeled_exception (scope : Scopelang.Ast.ScopeName.t) (ctxt : Name_resolution.context)
    (item : Ast.scope_use_item Pos.marked) : unit =
  let scope_ctxt = Scopelang.Ast.ScopeMap.find scope ctxt.scopes in
  match Pos.unmark item with
  | Ast.Rule rule -> (
      match rule.rule_exception_to with
      | Ast.NotAnException | Ast.ExceptionToLabel _ -> ()
      (* If this is an unlabeled exception, we check that it has a unique default definition *)
      | Ast.UnlabeledException -> (
          let def_key =
            Name_resolution.get_def_key (Pos.unmark rule.rule_name) scope ctxt
              (Pos.get_position rule.rule_consequence)
          in
          match Desugared.Ast.ScopeDefMap.find_opt def_key scope_ctxt.default_rulemap with
          | None ->
              Errors.raise_spanned_error "This exception does not have a corresponding definition"
                (Pos.get_position item)
          | Some Ambiguous ->
              Errors.raise_spanned_error
                "This exception can refer to several definitions. Try using labels to disambiguate"
                (Pos.get_position item)
          | Some (Unique _) -> () ) )
  | Ast.Definition def -> (
      match def.definition_exception_to with
      | Ast.NotAnException | Ast.ExceptionToLabel _ -> ()
      (* If this is an unlabeled exception, we check that it has a unique default definition *)
      | Ast.UnlabeledException -> (
          let def_key =
            Name_resolution.get_def_key (Pos.unmark def.definition_name) scope ctxt
              (Pos.get_position def.definition_expr)
          in
          match Desugared.Ast.ScopeDefMap.find_opt def_key scope_ctxt.default_rulemap with
          | None ->
              Errors.raise_spanned_error "This exception does not have a corresponding definition"
                (Pos.get_position item)
          | Some Ambiguous ->
              Errors.raise_spanned_error
                "This exception can refer to several definitions. Try using labels to disambiguate"
                (Pos.get_position item)
          | Some (Unique _) -> () ) )
  | _ -> ()

(** Translates a surface scope use, which is a bunch of definitions *)
let process_scope_use (ctxt : Name_resolution.context) (prgm : Desugared.Ast.program)
    (use : Ast.scope_use) : Desugared.Ast.program =
  let name = fst use.scope_use_name in
  let scope_uid = Desugared.Ast.IdentMap.find name ctxt.scope_idmap in
  (* Make sure the scope exists *)
  let prgm =
    match Scopelang.Ast.ScopeMap.find_opt scope_uid prgm.program_scopes with
    | Some _ -> prgm
    | None -> assert false
    (* should not happen *)
  in
  let precond = use.scope_use_condition in
  List.iter (check_unlabeled_exception scope_uid ctxt) use.scope_use_items;
  List.fold_left (process_scope_use_item precond scope_uid ctxt) prgm use.scope_use_items

(** Main function of this module *)
let desugar_program (ctxt : Name_resolution.context) (prgm : Ast.program) : Desugared.Ast.program =
  let empty_prgm =
    {
      Desugared.Ast.program_structs =
        Scopelang.Ast.StructMap.map Scopelang.Ast.StructFieldMap.bindings
          ctxt.Name_resolution.structs;
      Desugared.Ast.program_enums =
        Scopelang.Ast.EnumMap.map Scopelang.Ast.EnumConstructorMap.bindings
          ctxt.Name_resolution.enums;
      Desugared.Ast.program_scopes =
        Scopelang.Ast.ScopeMap.mapi
          (fun s_uid s_context ->
            {
              Desugared.Ast.scope_vars =
                Desugared.Ast.IdentMap.fold
                  (fun _ v acc -> Scopelang.Ast.ScopeVarSet.add v acc)
                  s_context.Name_resolution.var_idmap Scopelang.Ast.ScopeVarSet.empty;
              Desugared.Ast.scope_sub_scopes = s_context.Name_resolution.sub_scopes;
              Desugared.Ast.scope_defs =
                Desugared.Ast.IdentMap.fold
                  (fun _ v acc ->
                    let x, y = Scopelang.Ast.ScopeVarMap.find v ctxt.Name_resolution.var_typs in
                    Desugared.Ast.ScopeDefMap.add (Desugared.Ast.ScopeDef.Var v)
                      (Desugared.Ast.RuleMap.empty, x, y)
                      acc)
                  s_context.Name_resolution.var_idmap Desugared.Ast.ScopeDefMap.empty;
              Desugared.Ast.scope_assertions = [];
              Desugared.Ast.scope_meta_assertions = [];
              Desugared.Ast.scope_uid = s_uid;
            })
          ctxt.Name_resolution.scopes;
    }
  in
  let processer_article_item (prgm : Desugared.Ast.program) (item : Ast.law_article_item) :
      Desugared.Ast.program =
    match item with
    | CodeBlock (block, _) ->
        List.fold_left
          (fun prgm item ->
            match Pos.unmark item with
            | Ast.ScopeUse use -> process_scope_use ctxt prgm use
            | _ -> prgm)
          prgm block
    | _ -> prgm
  in
  let rec processer_structure (prgm : Desugared.Ast.program) (item : Ast.law_structure) :
      Desugared.Ast.program =
    match item with
    | LawHeading (_, children) ->
        List.fold_left (fun prgm child -> processer_structure prgm child) prgm children
    | LawArticle (_, children) ->
        List.fold_left (fun prgm child -> processer_article_item prgm child) prgm children
    | MetadataBlock (b, c) -> processer_article_item prgm (CodeBlock (b, c))
    | IntermediateText _ | LawInclude _ -> prgm
  in

  let processer_item (prgm : Desugared.Ast.program) (item : Ast.program_item) :
      Desugared.Ast.program =
    match item with LawStructure s -> processer_structure prgm s
  in

  List.fold_left processer_item empty_prgm prgm.program_items