WavWriter {.requiresInit.} = object
  file: File
  channels: int
  samplerate: int
  samplesWritten: int

proc `=destroy`(w: var WavWriter) {....raises: [Exception], tags: [RootEffect].}

proc close(w: var WavWriter): void {....raises: [IOError], tags: [WriteIOEffect].}

proc init(_: typedesc[WavWriter]; filename: sink string;
          channels, samplerate: int): WavWriter {....raises: [IOError].}

proc write(w: var WavWriter; data: openArray[PcmF32]) {....raises: [IOError],
    tags: [WriteIOEffect].}