replio.sc

import $ivy.`org.typelevel::cats-effect:0.10-22efb61`, cats._, cats.implicits._, cats.effect._, scala.concurrent.duration._

def putStr(msg: String): IO[Unit] = IO(print(msg))
def putStrLn(msg: String): IO[Unit] = IO(println(msg))
def readLn: IO[String] = IO(Console.readLine)

val now: IO[Long] = IO(System.currentTimeMillis)

def time[A](ioa: IO[A]): IO[(FiniteDuration, A)] = for {
  start <- now
  a <- ioa
  end <- now
} yield ((end - start).millis, a)

def currentThread: IO[Thread] = IO(Thread.currentThread)
def currentThreadName: IO[String] = currentThread.map(_.getName)

def log[A: Show](a: A): IO[Unit] = for {
  threadName <- currentThreadName
  time <- now
  msg = show"[$time] ($threadName) $a"
  _ <- putStrLn(msg)
} yield ()

def logIO[A: Show](ioa: IO[A]): IO[A] = ioa.flatTap(a => log(a))

def trace[A](desc: String, ioa: IO[A]): IO[A] = for {
  _ <- log(s"Before $desc")
  result <- time(ioa)
  (elapsed, a) = result
  _ <- log(s"After $desc - took $elapsed")
} yield a

implicit class IoExtensions[A](val ioa: IO[A]) extends AnyVal {
  def log(implicit s: Show[A]): IO[A] = replio.logIO(ioa)
  def trace(desc: String): IO[A] = replio.trace(desc, ioa)
}