Source file reason_oprint.ml

(*
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 *
 *  Xavier Leroy, projet Cristal, INRIA Rocquencourt
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(* Hello! Welcome to the Reason "outcome printer" logic. This logic takes the
   AST nodes and turn them into text, for Merlin, rtop and terminal errors
   reporting to be in Reason syntax.

   If you've navigated around in the Reason codebase, you might have seen the
   other printer called reason_pprint_ast, our actual, main pretty-printer. Why
   is this one separated from reason_pprint_ast? Because the outcome printer's
   use-case is a bit different and needs different entry points blablabla...
   These are mostly excuses. But for example, currently, `Js.t({. foo: bar})` by
   itself is *invalid syntax* for a pretty printer (the correct, minimal valid
   code would be `type myObject = Js.t({. foo: bar})`), but the terminal error
   report do want to provide just that snippet and have you print it. Hopefully
   OCaml can unify actual code pretty-printing and terminal type info pretty-
   printing one day.

   This also means the outcome printer doesn't use the normal Parsetree,
   Ast_helper and others you might have seen in other files. It has its own
   small AST definition here:
   https://github.com/ocaml/ocaml/blob/4.04/typing/outcometree.mli

   The rest of this file's logic is just pattern-matching on these tree node
   variants & using Format to pretty-print them nicely. *)

open Format
module Reason_ast = Reason_omp.Ast_414
module Outcometree = Reason_ast.Outcometree
open Outcometree

exception Ellipsis

let cautious f ppf arg = try f ppf arg with Ellipsis -> fprintf ppf "..."

let rec print_ident ppf = function
  | Oide_ident s -> pp_print_string ppf s.printed_name
  | Oide_dot (id, s) ->
    print_ident ppf id;
    pp_print_char ppf '.';
    pp_print_string ppf s
  | Oide_apply (id1, id2) ->
    fprintf ppf "%a(%a)" print_ident id1 print_ident id2

let parenthesized_ident name =
  List.mem name ~set:[ "or"; "mod"; "land"; "lor"; "lxor"; "lsl"; "lsr"; "asr" ]
  ||
  match name.[0] with
  | 'a' .. 'z' | 'A' .. 'Z' | '\223' .. '\246' | '\248' .. '\255' | '_' -> false
  | _ -> true

let value_ident ppf name =
  if parenthesized_ident name
  then fprintf ppf "( %s )" (Reason_syntax_util.ml_to_reason_swap name)
  else pp_print_string ppf name

(* Values *)

let valid_float_lexeme s =
  let l = String.length s in
  let rec loop i =
    if i >= l
    then s ^ "."
    else match s.[i] with '0' .. '9' | '-' -> loop (i + 1) | _ -> s
  in
  loop 0

let float_repres f =
  match classify_float f with
  | FP_nan -> "nan"
  | FP_infinite -> if f < 0.0 then "neg_infinity" else "infinity"
  | _ ->
    let float_val =
      let s1 = Printf.sprintf "%.12g" f in
      if f = float_of_string s1
      then s1
      else
        let s2 = Printf.sprintf "%.15g" f in
        if f = float_of_string s2 then s2 else Printf.sprintf "%.18g" f
    in
    valid_float_lexeme float_val

let parenthesize_if_neg ppf fmt v isneg =
  if isneg then pp_print_char ppf '(';
  fprintf ppf fmt v;
  if isneg then pp_print_char ppf ')'

let print_out_value ppf tree =
  let rec print_tree_1 ppf = function
    (* for the next few cases, please see context at
       https://github.com/facebook/reason/pull/1516#issuecomment-337069150 *)
    | Oval_constr
        (name, [ Oval_constr (Oide_ident { printed_name = "()" }, []) ]) ->
      (* for normal variants, but sugar Foo(()) to Foo() *)
      fprintf ppf "@[<1>%a()@]" print_ident name
    | Oval_constr (name, [ param ]) ->
      (* for normal variants *)
      fprintf ppf "@[<1>%a(%a)@]" print_ident name print_constr_param param
    | Oval_constr (name, (_ :: _ as params)) ->
      fprintf
        ppf
        "@[<1>%a(%a)@]"
        print_ident
        name
        (print_tree_list print_tree_1 ",")
        params
    | Oval_variant
        (name, Some (Oval_constr (Oide_ident { printed_name = "()" }, []))) ->
      (* for polymorphic variants, but sugar `foo(()) to `foo() *)
      fprintf ppf "@[<2>`%s()@]" name
    | Oval_variant (name, Some param) ->
      (* for polymorphic variants *)
      fprintf ppf "@[<2>`%s(%a)@]" name print_constr_param param
    | tree -> print_simple_tree ppf tree
  and print_constr_param ppf = function
    | Oval_int i -> parenthesize_if_neg ppf "%i" i (i < 0)
    | Oval_int32 i -> parenthesize_if_neg ppf "%lil" i (i < 0l)
    | Oval_int64 i -> parenthesize_if_neg ppf "%LiL" i (i < 0L)
    | Oval_nativeint i -> parenthesize_if_neg ppf "%nin" i (i < 0n)
    | Oval_float f -> parenthesize_if_neg ppf "%s" (float_repres f) (f < 0.0)
    | tree -> print_simple_tree ppf tree
  and print_simple_tree ppf = function
    | Oval_int i -> fprintf ppf "%i" i
    | Oval_int32 i -> fprintf ppf "%lil" i
    | Oval_int64 i -> fprintf ppf "%LiL" i
    | Oval_nativeint i -> fprintf ppf "%nin" i
    | Oval_float f -> pp_print_string ppf (float_repres f)
    | Oval_char c -> fprintf ppf "%C" c
    | Oval_string (s, _, _) ->
      (try fprintf ppf "\"%s\"" (Reason_syntax_util.escape_string s) with
      | Invalid_argument s when s = "String.create" ->
        fprintf ppf "<huge string>")
    | Oval_list tl ->
      fprintf ppf "@[<1>[%a]@]" (print_tree_list print_tree_1 ",") tl
    | Oval_array tl ->
      fprintf ppf "@[<2>[|%a|]@]" (print_tree_list print_tree_1 ",") tl
    | Oval_constr (name, []) -> print_ident ppf name
    | Oval_variant (name, None) -> fprintf ppf "`%s" name
    | Oval_stuff s -> pp_print_string ppf s
    | Oval_record fel ->
      fprintf ppf "@[<1>{%a}@]" (cautious (print_fields true)) fel
    | Oval_ellipsis -> raise Ellipsis
    | Oval_printer f -> f ppf
    | Oval_tuple tree_list ->
      fprintf ppf "@[<1>(%a)@]" (print_tree_list print_tree_1 ",") tree_list
    | tree -> fprintf ppf "@[<1>(%a)@]" (cautious print_tree_1) tree
  and print_fields first ppf = function
    | [] -> ()
    | (name, tree) :: fields ->
      if not first then fprintf ppf ",@ ";
      fprintf ppf "@[<1>%a:@ %a@]" print_ident name (cautious print_tree_1) tree;
      print_fields false ppf fields
  and print_tree_list print_item sep ppf tree_list =
    let rec print_list first ppf = function
      | [] -> ()
      | tree :: tree_list ->
        if not first then fprintf ppf "%s@ " sep;
        print_item ppf tree;
        print_list false ppf tree_list
    in
    cautious (print_list true) ppf tree_list
  in
  cautious print_tree_1 ppf tree

(* Types *)

let rec print_list_init pr sep ppf = function
  | [] -> ()
  | a :: l ->
    sep ppf;
    pr ppf a;
    print_list_init pr sep ppf l

let rec print_list pr sep ppf = function
  | [] -> ()
  | [ a ] -> pr ppf a
  | a :: l ->
    pr ppf a;
    sep ppf;
    print_list pr sep ppf l

let pr_present =
  print_list (fun ppf s -> fprintf ppf "`%s" s) (fun ppf -> fprintf ppf "@ ")

let pr_vars =
  print_list (fun ppf s -> fprintf ppf "'%s" s) (fun ppf -> fprintf ppf "@ ")

let get_label lbl =
  if lbl = ""
  then Reason_ast.Asttypes.Nolabel
  else if String.get lbl 0 = '?'
  then Optional (String.sub lbl ~pos:1 ~len:(String.length lbl - 1))
  else Labelled lbl

let get_arg_suffix ppf lab =
  match get_label lab with
  | Nolabel -> ""
  | Labelled lab ->
    pp_print_string ppf "~";
    pp_print_string ppf lab;
    pp_print_string ppf ": ";
    ""
  | Optional lab ->
    pp_print_string ppf "~";
    pp_print_string ppf lab;
    pp_print_string ppf ": ";
    "=?"

let rec print_out_type ppf = function
  | Otyp_alias (ty, s) -> fprintf ppf "@[%a@ as '%s@]" print_out_type ty s
  | Otyp_poly (sl, ty) ->
    fprintf ppf "@[<hov 2>%a.@ %a@]" pr_vars sl print_out_type ty
  | ty -> print_out_type_1 ~uncurried:false ppf ty

and print_arg ppf (lab, typ) =
  let suffix = get_arg_suffix ppf lab in
  print_out_type_2 ppf typ;
  pp_print_string ppf suffix

and print_out_type_1 ~uncurried ppf = function
  | Otyp_arrow _ as x ->
    let rec collect_args acc typ =
      match typ with
      | Otyp_arrow (lbl, ty1, ty2) -> collect_args ((lbl, ty1) :: acc) ty2
      | _ -> List.rev acc, typ
    in
    pp_open_box ppf 0;
    let args, result = collect_args [] x in
    let should_wrap_with_parens =
      (* uncurried arguments are always wrapped in parens *)
      if uncurried
      then true
      else
        match args with
        | [ (_, Otyp_tuple _) ] -> true
        | [ (_, Otyp_arrow _) ] -> true
        (* single argument should not be wrapped *)
        | [ ("", _) ] -> false
        | _ -> true
    in
    if should_wrap_with_parens then pp_print_string ppf "(";
    if uncurried then fprintf ppf ".@ ";
    print_list print_arg (fun ppf -> fprintf ppf ",@ ") ppf args;
    if should_wrap_with_parens then pp_print_string ppf ")";

    pp_print_string ppf " =>";
    pp_print_space ppf ();
    print_out_type_1 ~uncurried ppf result;
    pp_close_box ppf ()
  | ty -> print_out_type_2 ppf ty

and print_out_type_2 ppf = function
  | Otyp_tuple tyl ->
    fprintf ppf "@[<0>(%a)@]" (print_typlist print_simple_out_type ",") tyl
  | ty -> print_simple_out_type ppf ty

and print_simple_out_type ppf = function
  | Otyp_class (ng, id, tyl) ->
    fprintf
      ppf
      "@[%s#%a%a@]"
      (if ng then "_" else "")
      print_ident
      id
      print_typargs
      tyl
  (* Melange-specific external. See the manual for the usage of [@bs]. This
     [@bs] is processed into a type that looks like `Js.Internal.fn ...`. This
     leaks during error reporting, where the type is printed. Here, we print it
     back from `Js.Internal.fn([ `Arity_2 ('c, 'd) ], 'e)` into `('a => 'b =>
     int) [@bs]` *)
  (* same for `Js.Internal.fn(...)`. Either might shown *)
  | Otyp_constr
      ( (Oide_dot
           ( ( Oide_dot (Oide_ident { printed_name = "Js" }, "Internal")
             | Oide_ident { printed_name = "Js_internal" } )
           , (("fn" | "meth") as name) ) as id)
      , ([ Otyp_variant (_, Ovar_fields [ (variant, _, tys) ], _, _); result ]
         as tyl) ) ->
    (* Otyp_arrow *)
    let make tys result =
      if tys = []
      then
        Otyp_arrow
          ("", Otyp_constr (Oide_ident { printed_name = "unit" }, []), result)
      else
        match tys with
        | [ (Otyp_tuple tys as single) ] ->
          if variant = "Arity_1"
          then Otyp_arrow ("", single, result)
          else
            List.fold_right
              ~f:(fun x acc -> Otyp_arrow ("", x, acc))
              tys
              ~init:result
        | [ single ] -> Otyp_arrow ("", single, result)
        | _ -> raise_notrace Not_found
    in
    (match make tys result with
    | exception _ ->
      pp_open_box ppf 0;
      print_typargs ppf tyl;
      print_ident ppf id;
      pp_close_box ppf ()
    | res ->
      (match name with
      | "fn" -> print_out_type_1 ~uncurried:true ppf res
      | "meth" ->
        fprintf
          ppf
          "@[<0>(%a)@ [@mel.meth]@]"
          (print_out_type_1 ~uncurried:false)
          res
      | _ -> assert false))
  (* also Melange-specific. See the comment in the previous pattern *)
  | Otyp_constr
      ( (Oide_dot
           ( ( Oide_dot (Oide_ident { printed_name = "Js" }, "Internal")
             | Oide_ident { printed_name = "Js_internal" } )
           , "meth_callback" ) as id)
      , ([ Otyp_variant (_, Ovar_fields [ (variant, _, tys) ], _, _); result ]
         as tyl) ) ->
    let make tys result =
      match tys with
      | [ (Otyp_tuple tys as single) ] ->
        if variant = "Arity_1"
        then Otyp_arrow ("", single, result)
        else
          List.fold_right
            ~f:(fun x acc -> Otyp_arrow ("", x, acc))
            tys
            ~init:result
      | [ single ] -> Otyp_arrow ("", single, result)
      | _ -> raise_notrace Not_found
    in
    (match make tys result with
    | exception _ ->
      pp_open_box ppf 0;
      print_typargs ppf tyl;
      print_ident ppf id;
      pp_close_box ppf ()
    | res ->
      fprintf
        ppf
        "@[<0>(%a)@ [@mel.this]@]"
        (print_out_type_1 ~uncurried:false)
        res)
  (* also Melange-specific. Turns Js.t({. foo: bar}) into {. "foo": bar} *)
  | Otyp_constr
      ( Oide_dot (Oide_ident { printed_name = "Js" }, "t")
      , [ Otyp_object (fields, rest) ] ) ->
    let dot =
      match rest with
      | Some non_gen -> (if non_gen then "_" else "") ^ ".."
      | None -> "."
    in
    fprintf
      ppf
      "@[<2>{%s %a}@]"
      dot
      (print_object_fields ~quote_fields:true)
      fields
  | Otyp_constr (id, tyl) ->
    pp_open_box ppf 0;
    print_ident ppf id;
    (match tyl with [] -> () | _ -> print_typargs ppf tyl);
    pp_close_box ppf ()
  | Otyp_object (fields, rest) ->
    let dot =
      match rest with
      | Some non_gen -> (if non_gen then "_" else "") ^ ".."
      | None -> "."
    in
    fprintf
      ppf
      "@[<2>{%s %a}@]"
      dot
      (print_object_fields ~quote_fields:false)
      fields
  | Otyp_stuff s -> pp_print_string ppf s
  | Otyp_var (ng, s) -> fprintf ppf "'%s%s" (if ng then "_" else "") s
  | Otyp_variant (non_gen, row_fields, closed, tags) ->
    let print_present ppf = function
      | None | Some [] -> ()
      | Some l -> fprintf ppf "@;<1 -2>> @[<hov>%a@]" pr_present l
    in
    let print_fields ppf = function
      | Ovar_fields fields ->
        print_list
          print_row_field
          (fun ppf -> fprintf ppf "@;<1 -2>| ")
          ppf
          fields
      | Ovar_typ typ -> print_simple_out_type ppf typ
    in
    fprintf
      ppf
      "%s[%s@[<hv>@[<hv>%a@]%a ]@]"
      (if non_gen then "_" else "")
      (if closed
       then if tags = None then " " else "< "
       else if tags = None
       then "> "
       else "? ")
      print_fields
      row_fields
      print_present
      tags
  | (Otyp_alias _ | Otyp_poly _) as ty ->
    fprintf ppf "@[<1>(%a)@]" print_out_type ty
  | (Otyp_tuple _ | Otyp_arrow _) as ty ->
    (* no parentheses needed; the callsites already wrap these *)
    fprintf ppf "@[<1>%a@]" print_out_type ty
  | Otyp_abstract | Otyp_open | Otyp_sum _ | Otyp_record _ | Otyp_manifest (_, _)
    ->
    ()
  | Otyp_module (p, ntyls) ->
    fprintf ppf "@[<1>(module %a" print_ident p;
    let first = ref true in
    List.iter
      ~f:(fun (s, t) ->
        let sep =
          if !first
          then (
            first := false;
            "with")
          else "and"
        in
        fprintf ppf " %s type %s = %a" sep s print_out_type t)
      ntyls;
    fprintf ppf ")@]"
  | Otyp_attribute (t, attr) ->
    fprintf ppf "@[<1>(%a [@@%s])@]" print_out_type t attr.oattr_name

and print_object_fields ~quote_fields ppf = function
  | [] -> ()
  | [ (field, typ) ] ->
    let field = if quote_fields then "\"" ^ field ^ "\"" else field in
    fprintf ppf "%s: %a" field print_out_type typ;
    (print_object_fields ~quote_fields) ppf []
  | (field, typ) :: rest ->
    let field = if quote_fields then "\"" ^ field ^ "\"" else field in
    fprintf
      ppf
      "%s: %a,@ %a"
      field
      print_out_type
      typ
      (print_object_fields ~quote_fields)
      rest

and print_row_field ppf (l, opt_amp, tyl) =
  let pr_of ppf = if opt_amp then fprintf ppf " &@ " else fprintf ppf "" in
  let parens =
    match tyl with
    | [ Otyp_tuple _ ] -> false (* tuples already have parentheses *)
    (* [< `Ok(string & int) ] ----> string & int
     * [< `Ok(string) ] -----> string *)
    | _ :: _ -> true
    | _ -> false
  in
  fprintf
    ppf
    "@[<hv 2>`%s%t%s%a%s@]"
    l
    pr_of
    (if parens then "(" else "")
    (print_typlist print_out_type " &")
    tyl
    (if parens then ")" else "")

and print_typlist print_elem sep ppf = function
  | [] -> ()
  | [ ty ] -> print_elem ppf ty
  | ty :: tyl ->
    print_elem ppf ty;
    pp_print_string ppf sep;
    pp_print_space ppf ();
    print_typlist print_elem sep ppf tyl

and print_out_wrap_type ppf = function
  | Otyp_constr (_, _ :: _) as ty -> print_out_type ppf ty
  | ty -> print_simple_out_type ppf ty

and print_typargs ppf = function
  | [] -> ()
  | [ ty1 ] ->
    pp_print_string ppf "(";
    print_out_wrap_type ppf ty1;
    pp_print_string ppf ")"
  | tyl ->
    pp_print_string ppf "(";
    pp_open_box ppf 1;
    print_typlist print_out_wrap_type "," ppf tyl;
    pp_close_box ppf ();
    pp_print_string ppf ")"

let out_type = ref print_out_type

let variance = function
  | Reason_omp.Ast_414.Asttypes.NoVariance -> ""
  | Covariant -> "+"
  | Contravariant -> "-"

let type_parameter ppf (ty, (var, _)) =
  fprintf ppf "%s%s" (variance var) (if ty = "_" then ty else "'" ^ ty)

let print_out_class_params ppf = function
  | [] -> ()
  | tyl ->
    fprintf
      ppf
      "(@[<1>%a@])@ "
      (print_list type_parameter (fun ppf -> fprintf ppf ",@ "))
      tyl

let rec print_out_class_type ppf = function
  | Octy_constr (id, tyl) ->
    let pr_tyl ppf = function
      | [] -> ()
      | tyl ->
        fprintf ppf "@[<1> %a@]" (print_typlist print_out_wrap_type "") tyl
    in
    fprintf ppf "@[%a%a@]" print_ident id pr_tyl tyl
  | Octy_arrow (lab, argument_type, return_class_type) ->
    (* class arrow types need to be printed differently. For one, you can't do:

       class a: a => b

       because due to existing parsing issues, the `a` neds to be wrapped in
       parens (unlike normal arrow types). We can change this logic once this is
       no longer true *)
    let rec print_class_type_arguments_that_might_be_arrow ppf = function
      | Otyp_arrow ("", typ1, typ2) ->
        fprintf
          ppf
          "@[%a,@ %a@]"
          print_out_type
          typ1
          print_class_type_arguments_that_might_be_arrow
          typ2
      | Otyp_arrow (_, typ1, typ2) ->
        fprintf
          ppf
          "@[~%s: %a,@ %a@]"
          lab
          print_out_type
          typ1
          print_class_type_arguments_that_might_be_arrow
          typ2
      | argument_not_arrow -> fprintf ppf "%a" print_out_type argument_not_arrow
    in
    fprintf
      ppf
      "@[(%a) =>@ %a@]"
      print_class_type_arguments_that_might_be_arrow
      argument_type
      print_out_class_type
      return_class_type
  | Octy_signature (self_ty, csil) ->
    let pr_param ppf = function
      | Some ty -> fprintf ppf "@ @[(%a)@]" print_out_type ty
      | None -> ()
    in
    fprintf
      ppf
      "@[<hv 2>@[<2>{%a@]@ %a@;<1 -2>}@]"
      pr_param
      self_ty
      (print_list print_out_class_sig_item (fun ppf -> fprintf ppf ";@ "))
      csil

and print_out_class_sig_item ppf = function
  | Ocsg_constraint (ty1, ty2) ->
    fprintf ppf "@[<2>as %a =@ %a@]" print_out_type ty1 print_out_type ty2
  | Ocsg_method (name, priv, virt, ty) ->
    fprintf
      ppf
      "@[<2>%s%s%s:@ %a@]"
      (if priv then "pri " else "pub ")
      (if virt then "virtual " else "")
      name
      print_out_type
      ty
  | Ocsg_value (name, mut, vr, ty) ->
    fprintf
      ppf
      "@[<2>val %s%s%s:@ %a@]"
      (if mut then "mutable " else "")
      (if vr then "virtual " else "")
      name
      print_out_type
      ty

(* Signature *)

let is_rec_next = function
  | Osig_class (_, _, _, _, Orec_next) :: _
  | Osig_class_type (_, _, _, _, Orec_next) :: _
  | Osig_module (_, _, Orec_next) :: _
  | Osig_type (_, Orec_next) :: _ ->
    true
  | _ -> false

let rec print_out_functor ppf = function
  | Omty_functor (None, mty_res) ->
    fprintf ppf "() %a" print_out_functor mty_res
  | Omty_functor (Some (name, mty_arg), mty_res) ->
    let name = match name with None -> "_" | Some name -> name in
    fprintf
      ppf
      "(%s : %a) => %a"
      name
      print_out_module_type
      mty_arg
      print_out_functor
      mty_res
  | m -> fprintf ppf "%a" print_out_module_type m

and print_out_module_type ppf = function
  | Omty_abstract -> ()
  | Omty_functor _ as t -> fprintf ppf "@[<2>%a@]" print_out_functor t
  | Omty_ident id -> fprintf ppf "%a" print_ident id
  | Omty_signature sg ->
    fprintf ppf "@[<hv 2>{@ %a@;<1 -2>}@]" print_out_signature sg
  | Omty_alias id -> fprintf ppf "(module %a)" print_ident id

and print_out_signature ppf = function
  | [] -> ()
  | [ item ] -> fprintf ppf "%a;" print_out_sig_item item
  | Osig_typext (ext, Oext_first) :: items ->
    (* Gather together the extension constructors *)
    let rec gather_extensions acc items =
      match items with
      | Osig_typext (ext, Oext_next) :: items ->
        gather_extensions
          ({ ocstr_name = ext.oext_name
           ; ocstr_args = ext.oext_args
           ; ocstr_return_type = ext.oext_ret_type
           }
          :: acc)
          items
      | _ -> List.rev acc, items
    in
    let exts, items =
      gather_extensions
        [ { ocstr_name = ext.oext_name
          ; ocstr_args = ext.oext_args
          ; ocstr_return_type = ext.oext_ret_type
          }
        ]
        items
    in
    let te =
      { otyext_name = ext.oext_type_name
      ; otyext_params = ext.oext_type_params
      ; otyext_constructors = exts
      ; otyext_private = ext.oext_private
      }
    in
    let sep = if is_rec_next items then "" else ";" in
    fprintf
      ppf
      "%a%s@ %a"
      print_out_type_extension
      te
      sep
      print_out_signature
      items
  | item :: items ->
    let sep = if is_rec_next items then "" else ";" in
    fprintf ppf "%a%s@ %a" print_out_sig_item item sep print_out_signature items

and print_out_sig_item ppf = function
  | Osig_class (vir_flag, name, params, clt, rs) ->
    fprintf
      ppf
      "@[<2>%s%s@ %s %a@,:@ %a@]"
      (if rs = Orec_next then "and" else "class")
      (if vir_flag then " virtual" else "")
      name
      print_out_class_params
      params
      print_out_class_type
      clt
  | Osig_class_type (vir_flag, name, params, clt, rs) ->
    fprintf
      ppf
      "@[<2>%s%s@ %s %a@,=@ %a@]"
      (if rs = Orec_next then "and" else "class type")
      (if vir_flag then " virtual" else "")
      name
      print_out_class_params
      params
      print_out_class_type
      clt
  | Osig_typext (ext, Oext_exception) ->
    fprintf
      ppf
      "@[<2>exception %a@]"
      print_out_constr
      { ocstr_name = ext.oext_name
      ; ocstr_args = ext.oext_args
      ; ocstr_return_type = ext.oext_ret_type
      }
  | Osig_typext (ext, _) -> print_out_extension_constructor ppf ext
  | Osig_modtype (name, Omty_abstract) ->
    fprintf ppf "@[<2>module type %s@]" name
  | Osig_modtype (name, mty) ->
    fprintf ppf "@[<2>module type %s =@ %a@]" name print_out_module_type mty
  | Osig_module (name, Omty_alias id, _) ->
    fprintf ppf "@[<2>module %s =@ %a@]" name print_ident id
  | Osig_module (name, mty, rs) ->
    fprintf
      ppf
      "@[<2>%s %s:@ %a@]"
      (match rs with
      | Orec_not -> "module"
      | Orec_first -> "module rec"
      | Orec_next -> "and")
      name
      print_out_module_type
      mty
  | Osig_type (td, rs) ->
    print_out_type_decl
      (match rs with
      | Orec_not -> "type nonrec"
      | Orec_first -> "type"
      | Orec_next -> "and")
      ppf
      td
  | Osig_ellipsis -> fprintf ppf "..."
  | Osig_value { oval_name; oval_type; oval_prims; oval_attributes } ->
    let printAttributes ppf =
      List.iter ~f:(fun a -> fprintf ppf "[@@%s]" a.oattr_name)
    in
    let keyword = if oval_prims = [] then "let" else "external" in
    let hackyMelangeExternalAnnotation, rhsValues =
      List.partition
        ~f:(fun item ->
          (* "MEL:" is considered as a Melange external annotation,
             `[@mel.module]` and the sort.

             "What's going on here? Isn't [@mel.foo] supposed to be an attribute
             in oval_attributes?" Usually yes. But here, we're intercepting
             things a little too late. Melange already finished its
             pre/post-processing work before we get to print anything. The
             original attribute is already gone, replaced by a "BS:asdfasdfasd"
             thing here. *)
          String.length item >= 4
          && item.[0] = 'M'
          && item.[1] = 'E'
          && item.[1] = 'L'
          && item.[3] = ':')
        oval_prims
    in
    let print_right_hand_side ppf = function
      | [] -> ()
      | s :: sl ->
        fprintf ppf "@ = \"%s\"" s;
        List.iter ~f:(fun s -> fprintf ppf "@ \"%s\"" s) sl
    in
    fprintf
      ppf
      "@[<2>%a%a%s %a:@ %a%a@]"
      (fun ppf -> List.iter ~f:(fun _ -> fprintf ppf "[@@mel...]@ "))
      hackyMelangeExternalAnnotation
      printAttributes
      oval_attributes
      keyword
      value_ident
      oval_name
      !out_type
      oval_type
      print_right_hand_side
      rhsValues

and print_out_type_decl kwd ppf td =
  let print_constraints ppf =
    List.iter
      ~f:(fun (ty1, ty2) ->
        fprintf
          ppf
          "@ @[<2>constraint %a =@ %a@]"
          print_out_type
          ty1
          print_out_type
          ty2)
      td.otype_cstrs
  in
  let type_defined ppf =
    match td.otype_params with
    | [] -> pp_print_string ppf td.otype_name
    | [ param ] -> fprintf ppf "@[%s(%a)@]" td.otype_name type_parameter param
    | _ ->
      fprintf
        ppf
        "@[%s(@[%a@])@]"
        td.otype_name
        (print_list type_parameter (fun ppf -> fprintf ppf ",@ "))
        td.otype_params
  in
  let print_manifest ppf = function
    | Otyp_manifest (ty, _) -> fprintf ppf " =@ %a" print_out_type ty
    | _ -> ()
  in
  let print_name_params ppf =
    fprintf ppf "%s %t%a" kwd type_defined print_manifest td.otype_type
  in
  let ty =
    match td.otype_type with Otyp_manifest (_, ty) -> ty | _ -> td.otype_type
  in
  let print_private ppf = function
    | Reason_omp.Ast_414.Asttypes.Private -> fprintf ppf " pri"
    | Public -> ()
  in
  let print_out_tkind ppf = function
    | Otyp_abstract -> ()
    | Otyp_record lbls ->
      fprintf
        ppf
        " =%a {%a@;<1 -2>}"
        print_private
        td.otype_private
        (print_list_init print_out_label (fun ppf -> fprintf ppf "@ "))
        lbls
    | Otyp_sum constrs ->
      fprintf
        ppf
        " =%a@;<1 2>%a"
        print_private
        td.otype_private
        (print_list print_out_constr (fun ppf -> fprintf ppf "@ | "))
        constrs
    | Otyp_open -> fprintf ppf " = .."
    | ty ->
      fprintf
        ppf
        " =%a@;<1 2>%a"
        print_private
        td.otype_private
        print_out_type
        ty
  in
  fprintf
    ppf
    "@[<2>@[<hv 2>%t%a@]%t@]"
    print_name_params
    print_out_tkind
    ty
    print_constraints

and print_out_constr
      ppf
      { ocstr_name = name; ocstr_args = tyl; ocstr_return_type = ret_type_opt }
  =
  match ret_type_opt with
  | None ->
    (match tyl with
    | [] -> pp_print_string ppf name
    | [ Otyp_record lbls ] ->
      fprintf
        ppf
        "@[<2>%s({%a@;<1 -2>})@]"
        name
        (print_list_init print_out_label (fun ppf -> fprintf ppf "@ "))
        lbls
    | _ ->
      fprintf
        ppf
        "@[<2>%s(%a)@]"
        name
        (print_typlist print_simple_out_type ",")
        tyl)
  | Some ret_type ->
    (match tyl with
    | [] -> fprintf ppf "@[<2>%s:@ %a@]" name print_simple_out_type ret_type
    | [ Otyp_record lbls ] ->
      fprintf
        ppf
        "@[<2>%s({%a@;<1 -2>}): %a@]"
        name
        (print_list_init print_out_label (fun ppf -> fprintf ppf "@ "))
        lbls
        print_simple_out_type
        ret_type
    | _ ->
      fprintf
        ppf
        "@[<2>%s(%a): %a@]"
        name
        (print_typlist print_simple_out_type ",")
        tyl
        print_simple_out_type
        ret_type)

and print_out_label ppf (name, mut, arg) =
  fprintf
    ppf
    "@[<2>%s%s:@ %a@],"
    (if mut then "mutable " else "")
    name
    print_out_type
    arg

and print_out_extension_constructor ppf ext =
  let print_extended_type ppf =
    let print_type_parameter ppf ty =
      fprintf ppf "%s" (if ty = "_" then ty else "'" ^ ty)
    in
    match ext.oext_type_params with
    | [] -> fprintf ppf "%s" ext.oext_type_name
    | [ ty_param ] ->
      fprintf ppf "@[%a@ %s@]" print_type_parameter ty_param ext.oext_type_name
    | _ ->
      fprintf
        ppf
        "@[(@[%a)@]@ %s@]"
        (print_list print_type_parameter (fun ppf -> fprintf ppf ",@ "))
        ext.oext_type_params
        ext.oext_type_name
  in
  fprintf
    ppf
    "@[<hv 2>type %t +=%s@;<1 2>%a@]"
    print_extended_type
    (if ext.oext_private = Reason_omp.Ast_414.Asttypes.Private
     then " pri"
     else "")
    print_out_constr
    { ocstr_name = ext.oext_name
    ; ocstr_args = ext.oext_args
    ; ocstr_return_type = ext.oext_ret_type
    }

and print_out_type_extension ppf te =
  let print_extended_type ppf =
    let print_type_parameter ppf ty =
      fprintf ppf "%s" (if ty = "_" then ty else "'" ^ ty)
    in
    match te.otyext_params with
    | [] -> fprintf ppf "%s" te.otyext_name
    | [ param ] ->
      fprintf ppf "@[%a@ %s@]" print_type_parameter param te.otyext_name
    | _ ->
      fprintf
        ppf
        "@[(@[%a)@]@ %s@]"
        (print_list print_type_parameter (fun ppf -> fprintf ppf ",@ "))
        te.otyext_params
        te.otyext_name
  in
  fprintf
    ppf
    "@[<hv 2>type %t +=%s@;<1 2>%a@]"
    print_extended_type
    (if te.otyext_private = Reason_omp.Ast_414.Asttypes.Private
     then " pri"
     else "")
    (print_list print_out_constr (fun ppf -> fprintf ppf "@ | "))
    te.otyext_constructors

(* Phrases *)

let print_out_exception ppf exn outv =
  match exn with
  | Sys.Break -> fprintf ppf "Interrupted.@."
  | Out_of_memory -> fprintf ppf "Out of memory during evaluation.@."
  | Stack_overflow ->
    fprintf ppf "Stack overflow during evaluation (looping recursion?).@."
  | _ -> fprintf ppf "@[Exception:@ %a.@]@." print_out_value outv

let rec print_items ppf = function
  | [] -> ()
  | (Osig_typext (ext, Oext_first), None) :: items ->
    (* Gather together extension constructors *)
    let rec gather_extensions acc items =
      match items with
      | (Osig_typext (ext, Oext_next), None) :: items ->
        gather_extensions
          ({ ocstr_name = ext.oext_name
           ; ocstr_args = ext.oext_args
           ; ocstr_return_type = ext.oext_ret_type
           }
          :: acc)
          items
      | _ -> List.rev acc, items
    in
    let exts, items =
      gather_extensions
        [ { ocstr_name = ext.oext_name
          ; ocstr_args = ext.oext_args
          ; ocstr_return_type = ext.oext_ret_type
          }
        ]
        items
    in
    let te =
      { otyext_name = ext.oext_type_name
      ; otyext_params = ext.oext_type_params
      ; otyext_constructors = exts
      ; otyext_private = ext.oext_private
      }
    in
    fprintf ppf "@[%a@]" print_out_type_extension te;
    if items <> [] then fprintf ppf "@ %a" print_items items
  | (tree, valopt) :: items ->
    (match valopt with
    | Some v ->
      fprintf ppf "@[<2>%a =@ %a;@]" print_out_sig_item tree print_out_value v
    | None -> fprintf ppf "@[%a;@]" print_out_sig_item tree);
    if items <> [] then fprintf ppf "@ %a" print_items items

let print_out_phrase ppf = function
  | Ophr_eval (outv, ty) ->
    fprintf ppf "@[- : %a@ =@ %a@]@." print_out_type ty print_out_value outv
  | Ophr_signature [] -> ()
  | Ophr_signature items -> fprintf ppf "@[<v>%a@]@." print_items items
  | Ophr_exception (exn, outv) -> print_out_exception ppf exn outv