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 lseek : Unix.file_descr -> int64 -> Unix.seek_command -> int64 val truncate : string -> int64 -> unit val ftruncate : Unix.file_descr -> int64 -> unit type stats = { st_dev : int; st_ino : int; st_kind : Unix.file_kind; st_perm : Unix.file_perm; st_nlink : int; st_uid : int; st_gid : int; st_rdev : int; st_size : int64; st_atime : float; st_mtime : float; st_ctime : float; } val stat : string -> Unix.LargeFile.stats val lstat : string -> Unix.LargeFile.stats val fstat : Unix.file_descr -> Unix.LargeFile.stats end