Below is the API for the OCaml standard library. It's directly copied over from the OCaml Manual, formatted to the Reason syntax and styled accordingly. The API docs are work-in-progress; we'll be polishing these gradually!
If you're targeting JavaScript, the API docs for BuckleScript includes all of below, plus JS-specific APIs.
module Type: sig .. end
val mk : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> ?docs:Docstrings.docs -> ?text:Docstrings.text -> ?params:(Parsetree.core_type * Asttypes.variance) 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.core_type list -> ?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