import expect

pub external type Iodata;

pub external fn prepend(Iodata, String) -> Iodata =
  "gleam__stdlib" "iodata_prepend";

pub external fn append(Iodata, String) -> Iodata =
  "gleam__stdlib" "iodata_append";

pub external fn from(List(String)) -> Iodata =
  "gleam__stdlib" "identity";

pub external fn to_string(Iodata) -> String =
  "erlang" "iolist_to_binary";

pub external fn byte_size(Iodata) -> Int =
  "erlang" "iolist_size";

test iodata {
  let iodata = from(["ello"])
    |> append(_, ",")
    |> append(_, " world!")
    |> prepend(_, "H")

  iodata
  |> to_string
  |> expect:equal(_, "Hello, world!")

  iodata
  |> byte_size
  |> expect:equal(_, 13)
}