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 Sig: sig .. end
val mk : ?loc:Ast_helper.loc -> Parsetree.signature_item_desc -> Parsetree.signature_item
val value : ?loc:Ast_helper.loc -> Parsetree.value_description -> Parsetree.signature_item
val type_ : ?loc:Ast_helper.loc -> Parsetree.type_declaration list -> Parsetree.signature_item
val type_extension : ?loc:Ast_helper.loc -> Parsetree.type_extension -> Parsetree.signature_item
val exception_ : ?loc:Ast_helper.loc -> Parsetree.extension_constructor -> Parsetree.signature_item
val module_ : ?loc:Ast_helper.loc -> Parsetree.module_declaration -> Parsetree.signature_item
val rec_module : ?loc:Ast_helper.loc -> Parsetree.module_declaration list -> Parsetree.signature_item
val modtype : ?loc:Ast_helper.loc -> Parsetree.module_type_declaration -> Parsetree.signature_item
val open_ : ?loc:Ast_helper.loc -> Parsetree.open_description -> Parsetree.signature_item
val include_ : ?loc:Ast_helper.loc -> Parsetree.include_description -> Parsetree.signature_item
val class_ : ?loc:Ast_helper.loc -> Parsetree.class_description list -> Parsetree.signature_item
val class_type : ?loc:Ast_helper.loc -> Parsetree.class_type_declaration list -> Parsetree.signature_item
val extension : ?loc:Ast_helper.loc -> ?attrs:Ast_helper.attrs -> Parsetree.extension -> Parsetree.signature_item
val attribute : ?loc:Ast_helper.loc -> Parsetree.attribute -> Parsetree.signature_item
val text : Docstrings.text -> Parsetree.signature_item list