Parsetree(3)

NAME
Parsetree - Abstract syntax tree produced by parsing

Module
Module Parsetree

Documentation

Module Parsetree
 : sig end

Abstract syntax tree produced by parsing

Warning: this module is unstable and part of Compiler_libs .

type constant = {
 pconst_desc : constant_desc ;
 pconst_loc : Location.t ;
 }

type constant_desc =
 | Pconst_integer of string * char option
  (* Integer constants such as 3 3l 3L 3n .

Suffixes [g-z][G-Z] are accepted by the parser. Suffixes except 'l' , 'L' and 'n' are rejected by the typechecker
 *)
 | Pconst_char of char
  (* Character such as 'c' .
 *)
 | Pconst_string of string * Location.t * string option
  (* Constant string such as "constant" or {delim|other constant|delim} .

The location span the content of the string, without the delimiters.
 *)
 | Pconst_float of string * char option
  (* Float constant such as 3.4 , 2e5 or 1.4e-4 .

Suffixes g-z G-Z are accepted by the parser. Suffixes are rejected by the typechecker.
 *)

type location_stack = Location.t list

  Extension points

type attribute = {
 attr_name : string Asttypes.loc ;
 attr_payload : payload ;
 attr_loc : Location.t ;
 }

Attributes such as [@id ARG] and [@@id ARG] .

Metadata containers passed around within the AST. The compiler ignores unknown attributes.

type extension = string Asttypes.loc * payload

Extension points such as [%id ARG] and [%%id ARG] .

Sub-language placeholder -- rejected by the typechecker.

type attributes = attribute list

type payload =
 | PStr of structure
 | PSig of signature
  (* : SIG in an attribute or an extension point
 *)
 | PTyp of core_type
  (* : T in an attribute or an extension point
 *)
 | PPat of pattern * expression option
  (* ? P or ? P when E , in an attribute or an extension point
 *)

  Core language

  Type expressions

type core_type = {
 ptyp_desc : core_type_desc ;
 ptyp_loc : Location.t ;
 ptyp_loc_stack : location_stack ;
 ptyp_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type core_type_desc =
 | Ptyp_any (* _
 *)
 | Ptyp_var of string
  (* A type variable such as 'a
 *)
 | Ptyp_arrow of Asttypes.arg_label * core_type * core_type
  (* Ptyp_arrow(lbl, T1, T2) represents:

- T1 -> T2 when lbl is Asttypes.arg_label.Nolabel ,

- ~l:T1 -> T2 when lbl is Asttypes.arg_label.Labelled ,

- ?l:T1 -> T2 when lbl is Asttypes.arg_label.Optional .
 *)
 | Ptyp_tuple of (string option * core_type) list
  (* Ptyp_tuple(tl) represents a product type:

- T1 * ... * Tn when tl is (None, T1); ...; (None, Tn)

- L1:T1 * ... * Ln:Tn when tl is (Some L1, T1); ...; (Some Ln, Tn)

-A mix, e.g., L1:T1 * T2 when tl is (Some L1, T1); (None, T2) Invariant: n >= 2 .
 *)
 | Ptyp_constr of Longident.t Asttypes.loc * core_type list
  (* Ptyp_constr(lident, l) represents:

- tconstr when l=[] ,

- T tconstr when l=[T] ,

- (T1, ..., Tn) tconstr when l=[T1 ; ... ; Tn] .
 *)
 | Ptyp_object of object_field list * Asttypes.closed_flag
  (* Ptyp_object([ l1:T1; ...; ln:Tn ], flag) represents:

- < l1:T1; ...; ln:Tn > when flag is Asttypes.closed_flag.Closed ,

- < l1:T1; ...; ln:Tn; .. > when flag is Asttypes.closed_flag.Open .
 *)
 | Ptyp_class of Longident.t Asttypes.loc * core_type list
  (* Ptyp_class(tconstr, l) represents:

- #tconstr when l=[] ,

- T #tconstr when l=[T] ,

- (T1, ..., Tn) #tconstr when l=[T1 ; ... ; Tn] .
 *)
 | Ptyp_alias of core_type * string Asttypes.loc
  (* T as 'a .
 *)
 | Ptyp_variant of row_field list * Asttypes.closed_flag * Asttypes.label list option
  (* Ptyp_variant([`A;`B], flag, labels) represents:

- [ `A|`B ] when flag is Asttypes.closed_flag.Closed , and labels is None ,

- [> `A|`B ] when flag is Asttypes.closed_flag.Open , and labels is None ,

- [< `A|`B ] when flag is Asttypes.closed_flag.Closed , and labels is Some [] ,

- [< `A|`B > `X `Y ] when flag is Asttypes.closed_flag.Closed , and labels is Some ["X";"Y"] .
 *)
 | Ptyp_poly of string Asttypes.loc list * core_type
  (* 'a1 ... 'an. T

Can only appear in the following context:

-As the Parsetree.core_type of a Parsetree.pattern_desc.Ppat_constraint node corresponding to a constraint on a let-binding:
    let x : 'a1 ... 'an. T = e ...

-Under Parsetree.class_field_kind.Cfk_virtual for methods (not values).

-As the Parsetree.core_type of a Parsetree.class_type_field_desc.Pctf_method node.

-As the Parsetree.core_type of a Parsetree.expression_desc.Pexp_poly node.

-As the Parsetree.label_declaration.pld_type field of a Parsetree.label_declaration .

-As a Parsetree.core_type of a Parsetree.core_type_desc.Ptyp_object node.

-As the Parsetree.value_description.pval_type field of a Parsetree.value_description .
 *)
 | Ptyp_package of package_type
  (* (module S) .
 *)
 | Ptyp_open of Longident.t Asttypes.loc * core_type
  (* M.(T)
 *)
 | Ptyp_extension of extension
  (* [%id] .
 *)
 | Ptyp_functor of Asttypes.arg_label * string Asttypes.loc * package_type * core_type
  (* (module M : S) -> ... : module-dependent arrow
 *)

type package_type = {
 ppt_path : Longident.t Asttypes.loc ;
 ppt_constraints : (Longident.t Asttypes.loc * core_type) list ;
 ppt_loc : Location.t ;
 ppt_attrs : attributes ;
 }

As Parsetree.package_type typed values:

- {ppt_path: S; ppt_constraints: []} represents (module S) ,

- {ppt_path: S; ppt_constraints: [(t1, T1) ; ... ; (tn, Tn)]} represents (module S with type t1 = T1 and ... and tn = Tn) .

type row_field = {
 prf_desc : row_field_desc ;
 prf_loc : Location.t ;
 prf_attributes : attributes ;
 }

type row_field_desc =
 | Rtag of Asttypes.label Asttypes.loc * bool * core_type list
  (* Rtag(`A, b, l) represents:

- `A when b is true and l is [] ,

- `A of T when b is false and l is [T] ,

- `A of T1 & .. & Tn when b is false and l is [T1;...Tn] ,

- `A of & T1 & .. & Tn when b is true and l is [T1;...Tn] .

-The bool field is true if the tag contains a constant (empty) constructor.

- & occurs when several types are used for the same constructor (see 4.2 in the manual)
 *)
 | Rinherit of core_type
  (* [ | t ]
 *)

type object_field = {
 pof_desc : object_field_desc ;
 pof_loc : Location.t ;
 pof_attributes : attributes ;
 }

type object_field_desc =
 | Otag of Asttypes.label Asttypes.loc * core_type
 | Oinherit of core_type

  Patterns

type pattern = {
 ppat_desc : pattern_desc ;
 ppat_loc : Location.t ;
 ppat_loc_stack : location_stack ;
 ppat_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type pattern_desc =
 | Ppat_any (* The pattern _ .
 *)
 | Ppat_var of string Asttypes.loc
  (* A variable pattern such as x
 *)
 | Ppat_alias of pattern * string Asttypes.loc
  (* An alias pattern such as P as 'a
 *)
 | Ppat_constant of constant
  (* Patterns such as 1 , 'a' , "true" , 1.0 , 1l , 1L , 1n
 *)
 | Ppat_interval of constant * constant
  (* Patterns such as 'a'..'z' .

Other forms of interval are recognized by the parser but rejected by the type-checker.
 *)
 | Ppat_tuple of (string option * pattern) list * Asttypes.closed_flag
  (* Ppat_tuple(pl, Closed) represents

- (P1, ..., Pn) when pl is (None, P1); ...; (None, Pn)

- (~L1:P1, ..., ~Ln:Pn) when pl is (Some L1, P1); ...; (Some Ln, Pn)

-A mix, e.g. (~L1:P1, P2) when pl is (Some L1, P1); (None, P2) Ppat_tuple(pl, Open) is similar, but indicates the pattern additionally ends in a .. .

Invariant:

-If Closed, n >= 2 .

-If Open, n >= 1 .
 *)
 | Ppat_construct of Longident.t Asttypes.loc * (string Asttypes.loc list * pattern) option
  (* Ppat_construct(C, args) represents:

- C when args is None ,

- C P when args is Some ([], P)

- C (P1, ..., Pn) when args is Some ([], Ppat_tuple [P1; ...; Pn])

- C (type a b) P when args is Some ([a; b], P)
 *)
 | Ppat_variant of Asttypes.label * pattern option
  (* Ppat_variant(`A, pat) represents:

- `A when pat is None ,

- `A P when pat is Some P
 *)
 | Ppat_record of (Longident.t Asttypes.loc * pattern) list * Asttypes.closed_flag
  (* Ppat_record([(l1, P1) ; ... ; (ln, Pn)], flag) represents:

- { l1=P1; ...; ln=Pn } when flag is Asttypes.closed_flag.Closed

- { l1=P1; ...; ln=Pn; _} when flag is Asttypes.closed_flag.Open Invariant: n > 0
 *)
 | Ppat_array of pattern list
  (* Pattern [| P1; ...; Pn |]
 *)
 | Ppat_or of pattern * pattern
  (* Pattern P1 | P2
 *)
 | Ppat_constraint of pattern * core_type
  (* Pattern (P : T)
 *)
 | Ppat_type of Longident.t Asttypes.loc
  (* Pattern #tconst
 *)
 | Ppat_lazy of pattern
  (* Pattern lazy P
 *)
 | Ppat_unpack of string option Asttypes.loc * package_type option
  (* Ppat_unpack(s, ptyp) represents:

- (module P : S) when s is Some "P" and ptyp is Some "S"

- (module _ : S) when s is None and ptyp is Some "S"

- (module P) when s is Some "P" and ptyp is None

- (module _) when s is None and ptyp is None
 *)
 | Ppat_exception of pattern
  (* Pattern exception P
 *)
 | Ppat_effect of pattern * pattern
 | Ppat_extension of extension
  (* Pattern [%id]
 *)
 | Ppat_open of Longident.t Asttypes.loc * pattern
  (* Pattern M.(P)
 *)

  Value expressions

type expression = {
 pexp_desc : expression_desc ;
 pexp_loc : Location.t ;
 pexp_loc_stack : location_stack ;
 pexp_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type expression_desc =
 | Pexp_ident of Longident.t Asttypes.loc
  (* Identifiers such as x and M.x
 *)
 | Pexp_constant of constant
  (* Expressions constant such as 1 , 'a' , "true" , 1.0 , 1l , 1L , 1n
 *)
 | Pexp_let of Asttypes.rec_flag * value_binding list * expression
  (* Pexp_let(flag, [(P1,E1) ; ... ; (Pn,En)], E) represents:

- let P1 = E1 and ... and Pn = EN in E when flag is Asttypes.rec_flag.Nonrecursive ,

- let rec P1 = E1 and ... and Pn = EN in E when flag is Asttypes.rec_flag.Recursive .
 *)
 | Pexp_function of function_param list * type_constraint option * function_body
  (* Pexp_function ([P1; ...; Pn], C, body) represents any construct involving fun or function , including:

- fun P1 ... Pn -> E when body = Pfunction_body E

- fun P1 ... Pn -> function p1 -> e1 | ... | pm -> em when body = Pfunction_cases [ p1 -> e1; ...; pm -> em ] C represents a type constraint or coercion placed immediately before the arrow, e.g. fun P1 ... Pn : ty -> ... when C = Some (Pconstraint ty) .

A function must have parameters: in Pexp_function (params, _, body) , if params does not contain a Pparam_val _ , body must be Pfunction_cases _ .
 *)
 | Pexp_apply of expression * (Asttypes.arg_label * expression) list
  (* Pexp_apply(E0, [(l1, E1) ; ... ; (ln, En)]) represents E0 ~l1:E1 ... ~ln:En

li can be Asttypes.arg_label.Nolabel (non labeled argument), Asttypes.arg_label.Labelled (labelled arguments) or Asttypes.arg_label.Optional (optional argument).

Invariant: n > 0
 *)
 | Pexp_match of expression * case list
  (* match E0 with P1 -> E1 | ... | Pn -> En
 *)
 | Pexp_try of expression * case list
  (* try E0 with P1 -> E1 | ... | Pn -> En
 *)
 | Pexp_tuple of (string option * expression) list
  (* Pexp_tuple(el) represents

- (E1, ..., En) when el is (None, E1); ...; (None, En)

- (~L1:E1, ..., ~Ln:En) when el is (Some L1, E1); ...; (Some Ln, En)

-A mix, e.g., (~L1:E1, E2) when el is (Some L1, E1); (None, E2) Invariant: n >= 2
 *)
 | Pexp_construct of Longident.t Asttypes.loc * expression option
  (* Pexp_construct(C, exp) represents:

- C when exp is None ,

- C E when exp is Some E ,

- C (E1, ..., En) when exp is Some (Pexp_tuple[E1;...;En])
 *)
 | Pexp_variant of Asttypes.label * expression option
  (* Pexp_variant(`A, exp) represents

- `A when exp is None

- `A E when exp is Some E
 *)
 | Pexp_record of (Longident.t Asttypes.loc * expression) list * expression option
  (* Pexp_record([(l1,P1) ; ... ; (ln,Pn)], exp0) represents

- { l1=P1; ...; ln=Pn } when exp0 is None

- { E0 with l1=P1; ...; ln=Pn } when exp0 is Some E0 Invariant: n > 0
 *)
 | Pexp_field of expression * Longident.t Asttypes.loc
  (* E.l
 *)
 | Pexp_setfield of expression * Longident.t Asttypes.loc * expression
  (* E1.l <- E2
 *)
 | Pexp_array of expression list
  (* [| E1; ...; En |]
 *)
 | Pexp_ifthenelse of expression * expression * expression option
  (* if E1 then E2 else E3
 *)
 | Pexp_sequence of expression * expression
  (* E1; E2
 *)
 | Pexp_while of expression * expression
  (* while E1 do E2 done
 *)
 | Pexp_for of pattern * expression * expression * Asttypes.direction_flag * expression
  (* Pexp_for(i, E1, E2, direction, E3) represents:

- for i = E1 to E2 do E3 done when direction is Asttypes.direction_flag.Upto

- for i = E1 downto E2 do E3 done when direction is Asttypes.direction_flag.Downto
 *)
 | Pexp_constraint of expression * core_type
  (* (E : T)
 *)
 | Pexp_coerce of expression * core_type option * core_type
  (* Pexp_coerce(E, from, T) represents

- (E :> T) when from is None ,

- (E : T0 :> T) when from is Some T0 .
 *)
 | Pexp_send of expression * Asttypes.label Asttypes.loc
  (* E # m
 *)
 | Pexp_new of Longident.t Asttypes.loc
  (* new M.c
 *)
 | Pexp_setinstvar of Asttypes.label Asttypes.loc * expression
  (* x <- 2
 *)
 | Pexp_override of (Asttypes.label Asttypes.loc * expression) list
  (* {< x1 = E1; ...; xn = En >}
 *)
 | Pexp_struct_item of structure_item * expression
  (* let SI in E
 *)
 | Pexp_assert of expression
  (* assert E .

Note: assert false is treated in a special way by the type-checker.
 *)
 | Pexp_lazy of expression
  (* lazy E
 *)
 | Pexp_poly of expression * core_type option
  (* Used for method bodies.

Can only be used as the expression under Parsetree.class_field_kind.Cfk_concrete for methods (not values).
 *)
 | Pexp_object of class_structure
  (* object ... end
 *)
 | Pexp_newtype of string Asttypes.loc * expression
  (* fun (type t) -> E
 *)
 | Pexp_pack of module_expr * package_type option
  (* (module ME) or (module ME : S) .
 *)
 | Pexp_letop of letop
  (* - let* P = E0 in E1

- let* P0 = E00 and* P1 = E01 in E1
 *)
 | Pexp_extension of extension
  (* [%id]
 *)
 | Pexp_unreachable (* .
 *)

type case = {
 pc_lhs : pattern ;
 pc_guard : expression option ;
 pc_rhs : expression ;
 }

Values of type Parsetree.case represents (P -> E) or (P when E0 -> E)

type letop = {
 let_ : binding_op ;
 ands : binding_op list ;
 body : expression ;
 }

type binding_op = {
 pbop_op : string Asttypes.loc ;
 pbop_pat : pattern ;
 pbop_exp : expression ;
 pbop_loc : Location.t ;
 }

type function_param_desc =
 | Pparam_val of Asttypes.arg_label * expression option * pattern
  (* Pparam_val (lbl, exp0, P) represents the parameter:

- P when lbl is Asttypes.arg_label.Nolabel and exp0 is None

- ~l:P when lbl is Asttypes.arg_label.Labelled and exp0 is None

- ?l:P when lbl is Asttypes.arg_label.Optional and exp0 is None

- ?l:(P = E0) when lbl is Asttypes.arg_label.Optional and exp0 is Some E0 Note: If E0 is provided, only Asttypes.arg_label.Optional is allowed.
 *)
 | Pparam_newtype of string Asttypes.loc
  (* Pparam_newtype x represents the parameter (type x) . x carries the location of the identifier, whereas the pparam_loc on the enclosing function_param node is the location of the (type x) as a whole.

Multiple parameters (type a b c) are represented as multiple Pparam_newtype nodes, let's say:

    [ { pparam_kind = Pparam_newtype a; pparam_loc = loc1 };
               { pparam_kind = Pparam_newtype b; pparam_loc = loc2 };
               { pparam_kind = Pparam_newtype c; pparam_loc = loc3 };
             ]

Here, the first loc loc1 is the location of (type a b c) , and the subsequent locs loc2 and loc3 are the same as loc1 , except marked as ghost locations. The locations on a , b , c , correspond to the variables a , b , and c in the source code.
 *)

type function_param = {
 pparam_loc : Location.t ;
 pparam_desc : function_param_desc ;
 }

type function_body =
 | Pfunction_body of expression
 | Pfunction_cases of case list * Location.t * attributes
  (* In Pfunction_cases (_, loc, attrs) , the location extends from the start of the function keyword to the end of the last case. The compiler will only use typechecking-related attributes from attrs , e.g. enabling or disabling a warning.
 *)

See the comment on Parsetree.expression_desc.Pexp_function .

type type_constraint =
 | Pconstraint of core_type
 | Pcoerce of core_type option * core_type
  (* See the comment on Parsetree.expression_desc.Pexp_function .
 *)

  Value descriptions

type value_description = {
 pval_name : string Asttypes.loc ;
 pval_type : core_type ;
 pval_prim : string list ;
 pval_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 pval_loc : Location.t ;
 }

Values of type Parsetree.value_description represents:

- val x: T , when Parsetree.value_description.pval_prim is []

- external x: T = "s1" ... "sn" when Parsetree.value_description.pval_prim is ["s1";..."sn"]

  Type declarations

type type_declaration = {
 ptype_name : string Asttypes.loc ;
 ptype_params : (core_type * (Asttypes.variance * Asttypes.injectivity)) list ; (* ('a1,...'an) t
 *)
 ptype_constraints : (core_type * core_type * Location.t) list ; (* ... constraint T1=T1' ... constraint Tn=Tn'
 *)
 ptype_kind : type_kind ;
 ptype_private : Asttypes.private_flag ; (* for = private ...
 *)
 ptype_manifest : core_type option ; (* represents = T
 *)
 ptype_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 ptype_loc : Location.t ;
 }

Here are type declarations and their representation, for various Parsetree.type_declaration.ptype_kind and Parsetree.type_declaration.ptype_manifest values:

- type t when type_kind is Parsetree.type_kind.Ptype_abstract , and manifest is None ,

- type t = T0 when type_kind is Parsetree.type_kind.Ptype_abstract , and manifest is Some T0 ,

- type t = C of T | ... when type_kind is Parsetree.type_kind.Ptype_variant , and manifest is None ,

- type t = T0 = C of T | ... when type_kind is Parsetree.type_kind.Ptype_variant , and manifest is Some T0 ,

- type t = {l: T; ...} when type_kind is Parsetree.type_kind.Ptype_record , and manifest is None ,

- type t = T0 = {l : T; ...} when type_kind is Parsetree.type_kind.Ptype_record , and manifest is Some T0 ,

- type t = .. when type_kind is Parsetree.type_kind.Ptype_open , and manifest is None .

- type t = external "gmp" when type_kind is Parsetree.type_kind.Ptype_external and manifest is None .

type type_kind =
 | Ptype_abstract
 | Ptype_variant of constructor_declaration list
 | Ptype_record of label_declaration list
  (* Invariant: non-empty list
 *)
 | Ptype_open
 | Ptype_external of string

type label_declaration = {
 pld_name : string Asttypes.loc ;
 pld_mutable : Asttypes.mutable_flag ;
 pld_type : core_type ;
 pld_loc : Location.t ;
 pld_attributes : attributes ; (* l : T [@id1] [@id2]
 *)
 }

- { ...; l: T; ... } when Parsetree.label_declaration.pld_mutable is Asttypes.mutable_flag.Immutable ,

- { ...; mutable l: T; ... } when Parsetree.label_declaration.pld_mutable is Asttypes.mutable_flag.Mutable . Note: T can be a Parsetree.core_type_desc.Ptyp_poly .

type constructor_declaration = {
 pcd_name : string Asttypes.loc ;
 pcd_vars : string Asttypes.loc list ;
 pcd_args : constructor_arguments ;
 pcd_res : core_type option ;
 pcd_loc : Location.t ;
 pcd_attributes : attributes ; (* C of ... [@id1] [@id2]
 *)
 }

type constructor_arguments =
 | Pcstr_tuple of core_type list
 | Pcstr_record of label_declaration list
  (* Values of type Parsetree.constructor_declaration represents the constructor arguments of:

- C of T1 * ... * Tn when res = None , and args = Pcstr_tuple [T1; ... ; Tn] ,

- C: T0 when res = Some T0 , and args = Pcstr_tuple [] ,

- C: T1 * ... * Tn -> T0 when res = Some T0 , and args = Pcstr_tuple [T1; ... ; Tn] ,

- C of {...} when res = None , and args = Pcstr_record [...] ,

- C: {...} -> T0 when res = Some T0 , and args = Pcstr_record [...] .
 *)

type type_extension = {
 ptyext_path : Longident.t Asttypes.loc ;
 ptyext_params : (core_type * (Asttypes.variance * Asttypes.injectivity)) list ;
 ptyext_constructors : extension_constructor list ;
 ptyext_private : Asttypes.private_flag ;
 ptyext_loc : Location.t ;
 ptyext_attributes : attributes ; (* ... @@id1 @@id2
 *)
 }

Definition of new extensions constructors for the extensive sum type t ( type t += ... ).

type extension_constructor = {
 pext_name : string Asttypes.loc ;
 pext_kind : extension_constructor_kind ;
 pext_loc : Location.t ;
 pext_attributes : attributes ; (* C of ... [@id1] [@id2]
 *)
 }

type type_exception = {
 ptyexn_constructor : extension_constructor ;
 ptyexn_loc : Location.t ;
 ptyexn_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 }

Definition of a new exception ( exception E ).

type extension_constructor_kind =
 | Pext_decl of string Asttypes.loc list * constructor_arguments * core_type option
  (* Pext_decl(existentials, c_args, t_opt) describes a new extension constructor. It can be:

- C of T1 * ... * Tn when:

- existentials is [] ,

- c_args is [T1; ...; Tn] ,

- t_opt is None

- C: T0 when

- existentials is [] ,

- c_args is [] ,

- t_opt is Some T0 .

- C: T1 * ... * Tn -> T0 when

- existentials is [] ,

- c_args is [T1; ...; Tn] ,

- t_opt is Some T0 .

- C: 'a... . T1 * ... * Tn -> T0 when

- existentials is ['a;...] ,

- c_args is [T1; ... ; Tn] ,

- t_opt is Some T0 .
 *)
 | Pext_rebind of Longident.t Asttypes.loc
  (* Pext_rebind(D) re-export the constructor D with the new name C
 *)

  Class language

  Type expressions for the class language

type class_type = {
 pcty_desc : class_type_desc ;
 pcty_loc : Location.t ;
 pcty_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type class_type_desc =
 | Pcty_constr of Longident.t Asttypes.loc * core_type list
  (* - c

- ['a1, ..., 'an] c
 *)
 | Pcty_signature of class_signature
  (* object ... end
 *)
 | Pcty_arrow of Asttypes.arg_label * core_type * class_type
  (* Pcty_arrow(lbl, T, CT) represents:

- T -> CT when lbl is Asttypes.arg_label.Nolabel ,

- ~l:T -> CT when lbl is Asttypes.arg_label.Labelled ,

- ?l:T -> CT when lbl is Asttypes.arg_label.Optional .
 *)
 | Pcty_extension of extension
  (* %id
 *)
 | Pcty_open of open_description * class_type
  (* let open M in CT
 *)

type class_signature = {
 pcsig_self : core_type ;
 pcsig_fields : class_type_field list ;
 }

Values of type class_signature represents:

- object('selfpat) ... end

- object ... end when Parsetree.class_signature.pcsig_self is Parsetree.core_type_desc.Ptyp_any

type class_type_field = {
 pctf_desc : class_type_field_desc ;
 pctf_loc : Location.t ;
 pctf_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 }

type class_type_field_desc =
 | Pctf_inherit of class_type
  (* inherit CT
 *)
 | Pctf_val of (Asttypes.label Asttypes.loc * Asttypes.mutable_flag * Asttypes.virtual_flag * core_type)
  (* val x: T
 *)
 | Pctf_method of (Asttypes.label Asttypes.loc * Asttypes.private_flag * Asttypes.virtual_flag * core_type)
  (* method x: T

Note: T can be a Parsetree.core_type_desc.Ptyp_poly .
 *)
 | Pctf_constraint of (core_type * core_type)
  (* constraint T1 = T2
 *)
 | Pctf_attribute of attribute
  (* [@@@id]
 *)
 | Pctf_extension of extension
  (* [%%id]
 *)

type 'a class_infos = {
 pci_virt : Asttypes.virtual_flag ;
 pci_params : (core_type * (Asttypes.variance * Asttypes.injectivity)) list ;
 pci_name : string Asttypes.loc ;
 pci_expr : 'a ;
 pci_loc : Location.t ;
 pci_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 }

Values of type class_expr class_infos represents:

- class c = ...

- class ['a1,...,'an] c = ...

- class virtual c = ... They are also used for "class type" declaration.

type class_description = class_type class_infos

type class_type_declaration = class_type class_infos

  Value expressions for the class language

type class_expr = {
 pcl_desc : class_expr_desc ;
 pcl_loc : Location.t ;
 pcl_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type class_expr_desc =
 | Pcl_constr of Longident.t Asttypes.loc * core_type list
  (* c and ['a1, ..., 'an] c
 *)
 | Pcl_structure of class_structure
  (* object ... end
 *)
 | Pcl_fun of Asttypes.arg_label * expression option * pattern * class_expr
  (* Pcl_fun(lbl, exp0, P, CE) represents:

- fun P -> CE when lbl is Asttypes.arg_label.Nolabel and exp0 is None ,

- fun ~l:P -> CE when lbl is Asttypes.arg_label.Labelled and exp0 is None ,

- fun ?l:P -> CE when lbl is Asttypes.arg_label.Optional and exp0 is None ,

- fun ?l:(P = E0) -> CE when lbl is Asttypes.arg_label.Optional and exp0 is Some E0 .
 *)
 | Pcl_apply of class_expr * (Asttypes.arg_label * expression) list
  (* Pcl_apply(CE, [(l1,E1) ; ... ; (ln,En)]) represents CE ~l1:E1 ... ~ln:En . li can be empty (non labeled argument) or start with ? (optional argument).

Invariant: n > 0
 *)
 | Pcl_let of Asttypes.rec_flag * value_binding list * class_expr
  (* Pcl_let(rec, [(P1, E1); ... ; (Pn, En)], CE) represents:

- let P1 = E1 and ... and Pn = EN in CE when rec is Asttypes.rec_flag.Nonrecursive ,

- let rec P1 = E1 and ... and Pn = EN in CE when rec is Asttypes.rec_flag.Recursive .
 *)
 | Pcl_constraint of class_expr * class_type
  (* (CE : CT)
 *)
 | Pcl_extension of extension
  (* [%id]
 *)
 | Pcl_open of open_description * class_expr
  (* let open M in CE
 *)

type class_structure = {
 pcstr_self : pattern ;
 pcstr_fields : class_field list ;
 }

Values of type Parsetree.class_structure represents:

- object(selfpat) ... end

- object ... end when Parsetree.class_structure.pcstr_self is Parsetree.pattern_desc.Ppat_any

type class_field = {
 pcf_desc : class_field_desc ;
 pcf_loc : Location.t ;
 pcf_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 }

type class_field_desc =
 | Pcf_inherit of Asttypes.override_flag * class_expr * string Asttypes.loc option
  (* Pcf_inherit(flag, CE, s) represents:

- inherit CE when flag is Asttypes.override_flag.Fresh and s is None ,

- inherit CE as x when flag is Asttypes.override_flag.Fresh and s is Some x ,

- inherit! CE when flag is Asttypes.override_flag.Override and s is None ,

- inherit! CE as x when flag is Asttypes.override_flag.Override and s is Some x
 *)
 | Pcf_val of (Asttypes.label Asttypes.loc * Asttypes.mutable_flag * class_field_kind)
  (* Pcf_val(x,flag, kind) represents:

- val x = E when flag is Asttypes.mutable_flag.Immutable and kind is Parsetree.class_field_kind.Cfk_concrete

- val virtual x: T when flag is Asttypes.mutable_flag.Immutable and kind is Parsetree.class_field_kind.Cfk_virtual

- val mutable x = E when flag is Asttypes.mutable_flag.Mutable and kind is Parsetree.class_field_kind.Cfk_concrete

- val mutable virtual x: T when flag is Asttypes.mutable_flag.Mutable and kind is Parsetree.class_field_kind.Cfk_virtual
 *)
 | Pcf_method of (Asttypes.label Asttypes.loc * Asttypes.private_flag * class_field_kind)
  (* - method x = E ( E can be a Parsetree.expression_desc.Pexp_poly )

- method virtual x: T ( T can be a Parsetree.core_type_desc.Ptyp_poly )
 *)
 | Pcf_constraint of (core_type * core_type)
  (* constraint T1 = T2
 *)
 | Pcf_initializer of expression
  (* initializer E
 *)
 | Pcf_attribute of attribute
  (* [@@@id]
 *)
 | Pcf_extension of extension
  (* [%%id]
 *)

type class_field_kind =
 | Cfk_virtual of core_type
 | Cfk_concrete of Asttypes.override_flag * expression

type class_declaration = class_expr class_infos

  Module language

  Type expressions for the module language

type module_type = {
 pmty_desc : module_type_desc ;
 pmty_loc : Location.t ;
 pmty_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type module_type_desc =
 | Pmty_ident of Longident.t Asttypes.loc
  (* Pmty_ident(S) represents S
 *)
 | Pmty_signature of signature
  (* sig ... end
 *)
 | Pmty_functor of functor_parameter * module_type
  (* functor(X : MT1) -> MT2
 *)
 | Pmty_with of module_type * with_constraint list
  (* MT with ...
 *)
 | Pmty_typeof of module_expr
  (* module type of ME
 *)
 | Pmty_extension of extension
  (* [%id]
 *)
 | Pmty_alias of Longident.t Asttypes.loc
  (* (module M)
 *)

type functor_parameter =
 | Unit (* ()
 *)
 | Named of string option Asttypes.loc * module_type
  (* Named(name, MT) represents:

- (X : MT) when name is Some X ,

- (_ : MT) when name is None
 *)

type signature = signature_item list

type signature_item = {
 psig_desc : signature_item_desc ;
 psig_loc : Location.t ;
 }

type signature_item_desc =
 | Psig_value of value_description
  (* - val x: T

- external x: T = "s1" ... "sn"
 *)
 | Psig_type of Asttypes.rec_flag * type_declaration list
  (* type t1 = ... and ... and tn = ...
 *)
 | Psig_typesubst of type_declaration list
  (* type t1 := ... and ... and tn := ...
 *)
 | Psig_typext of type_extension
  (* type t1 += ...
 *)
 | Psig_exception of type_exception
  (* exception C of T
 *)
 | Psig_module of module_declaration
  (* module X = M and module X : MT
 *)
 | Psig_modsubst of module_substitution
  (* module X := M
 *)
 | Psig_recmodule of module_declaration list
  (* module rec X1 : MT1 and ... and Xn : MTn
 *)
 | Psig_modtype of module_type_declaration
  (* module type S = MT and module type S
 *)
 | Psig_modtypesubst of module_type_declaration
  (* module type S := ...
 *)
 | Psig_open of open_description
  (* open X
 *)
 | Psig_include of include_description
  (* include MT
 *)
 | Psig_class of class_description list
  (* class c1 : ... and ... and cn : ...
 *)
 | Psig_class_type of class_type_declaration list
  (* class type ct1 = ... and ... and ctn = ...
 *)
 | Psig_attribute of attribute
  (* [@@@id]
 *)
 | Psig_extension of extension * attributes
  (* [%%id]
 *)

type module_declaration = {
 pmd_name : string option Asttypes.loc ;
 pmd_type : module_type ;
 pmd_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 pmd_loc : Location.t ;
 }

Values of type module_declaration represents S : MT

type module_substitution = {
 pms_name : string Asttypes.loc ;
 pms_manifest : Longident.t Asttypes.loc ;
 pms_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 pms_loc : Location.t ;
 }

Values of type module_substitution represents S := M

type module_type_declaration = {
 pmtd_name : string Asttypes.loc ;
 pmtd_type : module_type option ;
 pmtd_attributes : attributes ; (* ... [@@id1] [@@id2]
 *)
 pmtd_loc : Location.t ;
 }

Values of type module_type_declaration represents:

- S = MT ,

- S for abstract module type declaration, when Parsetree.module_type_declaration.pmtd_type is None .

type 'a open_infos = {
 popen_expr : 'a ;
 popen_override : Asttypes.override_flag ;
 popen_loc : Location.t ;
 popen_attributes : attributes ;
 }

Values of type 'a open_infos represents:

- open! X when Parsetree.open_infos.popen_override is Asttypes.override_flag.Override (silences the "used identifier shadowing" warning)

- open X when Parsetree.open_infos.popen_override is Asttypes.override_flag.Fresh

type open_description = Longident.t Asttypes.loc open_infos

Values of type open_description represents:

- open M.N

- open M(N).O

type open_declaration = module_expr open_infos

Values of type open_declaration represents:

- open M.N

- open M(N).O

- open struct ... end

type 'a include_infos = {
 pincl_mod : 'a ;
 pincl_loc : Location.t ;
 pincl_attributes : attributes ;
 }

type include_description = module_type include_infos

Values of type include_description represents include MT

type include_declaration = module_expr include_infos

Values of type include_declaration represents include ME

type with_constraint =
 | Pwith_type of Longident.t Asttypes.loc * type_declaration
  (* with type X.t = ...

Note: the last component of the longident must match the name of the type_declaration.
 *)
 | Pwith_module of Longident.t Asttypes.loc * Longident.t Asttypes.loc
  (* with module X.Y = Z
 *)
 | Pwith_modtype of Longident.t Asttypes.loc * module_type
  (* with module type X.Y = Z
 *)
 | Pwith_modtypesubst of Longident.t Asttypes.loc * module_type
  (* with module type X.Y := sig end
 *)
 | Pwith_typesubst of Longident.t Asttypes.loc * type_declaration
  (* with type X.t := ..., same format as [Pwith_type]
 *)
 | Pwith_modsubst of Longident.t Asttypes.loc * Longident.t Asttypes.loc
  (* with module X.Y := Z
 *)

  Value expressions for the module language

type module_expr = {
 pmod_desc : module_expr_desc ;
 pmod_loc : Location.t ;
 pmod_attributes : attributes ; (* ... [@id1] [@id2]
 *)
 }

type module_expr_desc =
 | Pmod_ident of Longident.t Asttypes.loc
  (* X
 *)
 | Pmod_structure of structure
  (* struct ... end
 *)
 | Pmod_functor of functor_parameter * module_expr
  (* functor(X : MT1) -> ME
 *)
 | Pmod_apply of module_expr * module_expr
  (* ME1(ME2)
 *)
 | Pmod_apply_unit of module_expr
  (* ME1()
 *)
 | Pmod_constraint of module_expr * module_type
  (* (ME : MT)
 *)
 | Pmod_unpack of expression
  (* (val E)
 *)
 | Pmod_extension of extension
  (* [%id]
 *)

type structure = structure_item list

type structure_item = {
 pstr_desc : structure_item_desc ;
 pstr_loc : Location.t ;
 }

type structure_item_desc =
 | Pstr_eval of expression * attributes
  (* E
 *)
 | Pstr_value of Asttypes.rec_flag * value_binding list
  (* Pstr_value(rec, [(P1, E1 ; ... ; (Pn, En))]) represents:

- let P1 = E1 and ... and Pn = EN when rec is Asttypes.rec_flag.Nonrecursive ,

- let rec P1 = E1 and ... and Pn = EN when rec is Asttypes.rec_flag.Recursive .
 *)
 | Pstr_primitive of value_description
  (* - val x: T

- external x: T = "s1" ... "sn"
 *)
 | Pstr_type of Asttypes.rec_flag * type_declaration list
  (* type t1 = ... and ... and tn = ...
 *)
 | Pstr_typext of type_extension
  (* type t1 += ...
 *)
 | Pstr_exception of type_exception
  (* - exception C of T

- exception C = M.X
 *)
 | Pstr_module of module_binding
  (* module X = ME
 *)
 | Pstr_recmodule of module_binding list
  (* module rec X1 = ME1 and ... and Xn = MEn
 *)
 | Pstr_modtype of module_type_declaration
  (* module type S = MT
 *)
 | Pstr_open of open_declaration
  (* open X
 *)
 | Pstr_class of class_declaration list
  (* class c1 = ... and ... and cn = ...
 *)
 | Pstr_class_type of class_type_declaration list
  (* class type ct1 = ... and ... and ctn = ...
 *)
 | Pstr_include of include_declaration
  (* include ME
 *)
 | Pstr_attribute of attribute
  (* [@@@id]
 *)
 | Pstr_extension of extension * attributes
  (* [%%id]
 *)

type value_constraint =
 | Pvc_constraint of {
 locally_abstract_univars : string Asttypes.loc list ;
 typ : core_type ;
 }
 | Pvc_coercion of {
 ground : core_type option ;
 coercion : core_type ;
 }
  (* - Pvc_constraint { locally_abstract_univars=[]; typ} is a simple type constraint on a value binding: let x : typ

-More generally, in Pvc_constraint { locally_abstract_univars; typ} locally_abstract_univars is the list of locally abstract type variables in let x: type a ... . typ

- Pvc_coercion { ground=None; coercion } represents let x :> typ

- Pvc_coercion { ground=Some g; coercion } represents let x : g :> typ
 *)

type value_binding = {
 pvb_pat : pattern ;
 pvb_expr : expression ;
 pvb_constraint : value_constraint option ;
 pvb_attributes : attributes ;
 pvb_loc : Location.t ;
 }

let pat : type_constraint = exp

type module_binding = {
 pmb_name : string option Asttypes.loc ;
 pmb_expr : module_expr ;
 pmb_attributes : attributes ;
 pmb_loc : Location.t ;
 }

Values of type module_binding represents module X = ME

  Toplevel

  Toplevel phrases

type toplevel_phrase =
 | Ptop_def of structure
 | Ptop_dir of toplevel_directive
  (* #use , #load ...
 *)

type toplevel_directive = {
 pdir_name : string Asttypes.loc ;
 pdir_arg : directive_argument option ;
 pdir_loc : Location.t ;
 }

type directive_argument = {
 pdira_desc : directive_argument_desc ;
 pdira_loc : Location.t ;
 }

type directive_argument_desc =
 | Pdir_string of string
 | Pdir_int of string * char option
 | Pdir_ident of Longident.t
 | Pdir_bool of bool