type (+'a, 's) io
type 's scheduler = {
  1. bind : 'a 'b. ('a, 's) io -> ('a -> ('b, 's) io) -> ('b, 's) io;
  2. return : 'a. 'a -> ('a, 's) io;
}
type where =
  1. | SET
  2. | CUR
  3. | END
type ('fd, 'error, 's) syscall = {
  1. seek : 'fd -> int64 -> where -> ((unit, 'error) result, 's) io;
  2. read : 'fd -> int -> ((string, 'error) result, 's) io;
  3. line : 'fd -> ((int * int * string, 'error) result, 's) io;
  4. read_int8 : 'fd -> ((int, 'error) result, 's) io;
  5. read_int16_ne : 'fd -> ((int, 'error) result, 's) io;
  6. read_int32_ne : 'fd -> ((int32, 'error) result, 's) io;
  7. read_int64_ne : 'fd -> ((int64, 'error) result, 's) io;
}