Created
October 16, 2013 10:08
-
-
Save seanparsons/7005543 to your computer and use it in GitHub Desktop.
Stacking ReaderT and OptionT.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import scalaz._,Scalaz._,scalaz.effect._,OptionT._,Kleisli._ | |
type OptionTIO[+X] = OptionT[IO, X] | |
val reader1: ReaderT[Option, Int, String] = kleisli[Option, Int, String](n => n.toString.some) | |
val reader2: ReaderT[IO, Int, String] = kleisli[IO, Int, String](n => IO((n * 2).toString)) | |
val convertedReader1: ReaderT[OptionTIO, Int, String] = reader1.mapK[OptionTIO, String](opt => optionT(IO(opt))) | |
val convertedReader2: ReaderT[OptionTIO, Int, String] = reader2.mapK[OptionTIO, String](io => io.liftM[OptionT]) | |
val composed = for { | |
first <- convertedReader1 | |
second <- convertedReader2 | |
} yield first + " - " + second | |
composed | |
.run(4) // ReaderT | |
.run // OptionT | |
.unsafePerformIO // IO |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment