OCaml compiler library : Ast_helper.Type

`sig
val mk :
?loc:Ast_helper.loc ->
?attrs:Ast_helper.attrs ->
?docs:Docstrings.docs ->
?text:Docstrings.text ->
?params:(Parsetree.core_type * (Asttypes.variance * Asttypes.injectivity))
list ->
?cstrs:(Parsetree.core_type * Parsetree.core_type * Ast_helper.loc) list ->
?kind:Parsetree.type_kind ->
?priv:Asttypes.private_flag ->
?manifest:Parsetree.core_type ->
Ast_helper.str -> Parsetree.type_declaration
val constructor :
?loc:Ast_helper.loc ->
?attrs:Ast_helper.attrs ->
?info:Docstrings.info ->
?args:Parsetree.constructor_arguments ->
?res:Parsetree.core_type ->
Ast_helper.str -> Parsetree.constructor_declaration
val field :
?loc:Ast_helper.loc ->
?attrs:Ast_helper.attrs ->
?info:Docstrings.info ->
?mut:Asttypes.mutable_flag ->
Ast_helper.str -> Parsetree.core_type -> Parsetree.label_declaration
end`