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.
sig val mk : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern_desc -> Parsetree.pattern val attr : Parsetree.pattern -> Parsetree.attribute -> Parsetree.pattern val any : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> unit -> Parsetree.pattern val var : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Ast_helper.str -> Parsetree.pattern val alias : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern -> Ast_helper.str -> Parsetree.pattern val constant : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Asttypes.constant -> Parsetree.pattern val interval : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Asttypes.constant -> Asttypes.constant -> Parsetree.pattern val tuple : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern list -> Parsetree.pattern val construct : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Ast_helper.lid -> Parsetree.pattern option -> Parsetree.pattern val variant : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Asttypes.label -> Parsetree.pattern option -> Parsetree.pattern val record : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> (Ast_helper.lid * Parsetree.pattern) list -> Asttypes.closed_flag -> Parsetree.pattern val array : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern list -> Parsetree.pattern val or_ : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern -> Parsetree.pattern -> Parsetree.pattern val constraint_ : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern -> Parsetree.core_type -> Parsetree.pattern val type_ : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Ast_helper.lid -> Parsetree.pattern val lazy_ : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern -> Parsetree.pattern val unpack : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Ast_helper.str -> Parsetree.pattern val exception_ : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.pattern -> Parsetree.pattern val extension : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.extension -> Parsetree.pattern end