Ghosts

Nano library that provides syntax niceties on top of cats

Rationale

Let's say you have val v: F[Either[A, B]] where F is some monad and you want to convert Either inside F. You have following options:

• Use nested map calls:

  v.map(_.map(f))

  Pros:

  • Pretty straightforward
  • Type of outer monad doesn't change - it's still F

  Cons:

  • Code become clattered with multiple map/flatMap calls

• Use EitherT:

  import cats.data.EitherT
      
  EitherT(v).map(f).value

  Pros:

  • Allows you to use it in for-comprehension

  Cons:

  • Type of outer monad changes - now it's EitherT instead of F and you can't directly pass your value to function that expects `F'.
  • Increased depth of monad's stack makes code harder to read
  • Code is clattered with EitherT's contructor calls

• Use this library:

  import ghosts.either._
      
  v.mapT(f)

  Pros:

  • Type of outer monad doesn't change: all methods of F are directly available to you, you can freely pass it to any fuction that expects F.
  • Depth of monad stack stays the same

  Cons:

  • Not suitable for use inside for-comprehension

How to use

Add the following to your build.sbt file: libraryDependencies += "com.github.mkulak" %% "ghosts" % "0.0.1"

List of Dependencies

org.typelevel" %% "cats" % "0.8.1"