Error handling and logging

EitherTLogging.scala

import cats._
import cats.data._
import cats.implicits._

object EitherTLogging {

    def divide[F[_]](dividend: Int, divisor: Int)(implicit F: ApplicativeError[F, String]): F[Int] = {
        if (divisor === 0) F.raiseError("division by zero")
        else F.pure(dividend / divisor)
    }

    type ErrorOr[A] = Either[String, A]
    
    def logDivide(a: Int, b: Int) : Writer[String, Either[String, Int]] = (
        divide[ErrorOr](a,b) match {
            case Left(e) => Writer("Computation failed\n", Left(e))
            case Right(n) => Writer(s"Divided $a by $b\n", Right(n))
        }
    )

    def test = {
        for(
            a <- EitherT(logDivide(10,2));
            b <- EitherT(logDivide(100,a));
            c <- EitherT(logDivide(b, 4))
        ) yield c

    }

    def failTest = {
        for(
            a <- EitherT(logDivide(10,2));
            b <- EitherT(logDivide(100,a));
            c <- EitherT(logDivide(b, 0));
            d <- EitherT(logDivide(c, 10))
        ) yield c

    }
    
    def main(args: Array[String]) : Unit = {
        println(s"Success:\n$test\n\n")
        println(s"Failure:\n$failTest")
    }

    /*
    Success:
        EitherT(WriterT((Divided 10 by 2
        Divided 100 by 5
        Divided 20 by 4
        ,Right(5))))


    Failure:
        EitherT(WriterT((Divided 10 by 2
        Divided 100 by 5
        Computation failed
        ,Left(division by zero))))
    */
}