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 core_type list
(* Ptyp_tuple([T1 ; ... ; Tn]) represents a product type T1 * ... * Tn .

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] .
*)

type package_type = Longident.t Asttypes.loc * (Longident.t Asttypes.loc * core_type) list

As Parsetree.package_type typed values:

- (S, []) represents (module S) ,

- (S, [(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 pattern list
(* Patterns (P1, ..., Pn) .

Invariant: n >= 2

*)
| 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
(* Ppat_unpack(s) represents:

- (module P) when s is Some "P"

- (module _) when s is None

Note: (module P : S) is represented as Ppat_constraint(Ppat_unpack(Some "P"), Ptyp_package S)

*)
| Ppat_exception of pattern
(* Pattern exception P

*)
| 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. Pexp_function (params, _, body) must have non-empty params or a Pfunction_cases _ body.
*)
| 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 expression list
(* Expressions (E1, ..., En)

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_letmodule of string option Asttypes.loc * module_expr * expression
(* let module M = ME in E

*)
| Pexp_letexception of extension_constructor * expression
(* let exception C 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
(* (module ME) .

(module ME : S) is represented as Pexp_constraint(Pexp_pack ME, Ptyp_package S)

*)
| Pexp_open of open_declaration * expression
(* - M.(E)

- let open M in E

- let open! M in E

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

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