Bracket typeclass in cats-effect 0.10.1

Question

I'm using cats-effect 0.10.1 and found out that there is no Bracket typeclass in this version. So this seems I need to introduce some workaround for that.

I'm designing function for Reading from some source (side-effect). So I have \

trait DataFormat

object StreamData{

  def apply[T](path: String)(f: (DataFormat, ReadableByteChannel) => T): IO[T] = 
  IO {
     val channel: ReadableByteChannel = Files.newByteChannel(path)
     try{
        val dataFormat: DataFormat = //...
        //in case of GZIP format open GZIPInputStream
        f(dataFormat, channel)
     } finally {
        if(channel != null) channel.close()
     }
  }
}

The problem with this is that f: (DataFormat, ReadableByteChannel) => T is impure. So I'd make it as f: (DataFormat, ReadableByteChannel) => IO[T] which makes resource releasing in the example above not possible (because I need to flatMap in this case).

Can you suggest any workarounds about it and yet keeping functions pure?

@YuvalItzchakov Unfortunately, no. I also cannot switch to `scalaz-effect` which also includes that. — Some Name, Jun 07 '18 at 12:54
@YuvalItzchakov I have some function that depending on the data-format and channel creates `fs2.Stream[IO, Array[Byte]]` and does some processing. But after that I want to release the channel, that's it. — Some Name, Jun 07 '18 at 12:55
How about creating a thin typeclass for resource releasing? Do you need any other properties for the effect around `T`? Do you need to `map`, `flatMap` etc? — Yuval Itzchakov, Jun 07 '18 at 12:55
@YuvalItzchakov You mean similar to `Bracket` of `1.0.0-RC`? Only `map`, but this look straightworward to implement. — Some Name, Jun 07 '18 at 13:02
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/172690/discussion-between-yuval-itzchakov-and-some-name). — Yuval Itzchakov, Jun 07 '18 at 13:04

Bracket typeclass in cats-effect 0.10.1

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