Standard Library
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 type t external repr : 'a -> Obj.t = "%identity" external obj : Obj.t -> 'a = "%identity" external magic : 'a -> 'b = "%identity" external is_block : Obj.t -> bool = "caml_obj_is_block" external is_int : Obj.t -> bool = "%obj_is_int" external tag : Obj.t -> int = "caml_obj_tag" external set_tag : Obj.t -> int -> unit = "caml_obj_set_tag" external size : Obj.t -> int = "%obj_size" external field : Obj.t -> int -> Obj.t = "%obj_field" external set_field : Obj.t -> int -> Obj.t -> unit = "%obj_set_field" val double_field : Obj.t -> int -> float val set_double_field : Obj.t -> int -> float -> unit external new_block : int -> int -> Obj.t = "caml_obj_block" external dup : Obj.t -> Obj.t = "caml_obj_dup" external truncate : Obj.t -> int -> unit = "caml_obj_truncate" external add_offset : Obj.t -> Int32.t -> Obj.t = "caml_obj_add_offset" val first_non_constant_constructor_tag : int val last_non_constant_constructor_tag : int val lazy_tag : int val closure_tag : int val object_tag : int val infix_tag : int val forward_tag : int val no_scan_tag : int val abstract_tag : int val string_tag : int val double_tag : int val double_array_tag : int val custom_tag : int val final_tag : int val int_tag : int val out_of_heap_tag : int val unaligned_tag : int val extension_name : 'a -> string val extension_id : 'a -> int val extension_slot : 'a -> Obj.t val marshal : Obj.t -> bytes val unmarshal : bytes -> int -> Obj.t * int end