Library is available for Scala 2.11, 2.12, 2.13.
Add it with:
libraryDependencies += "io.scalaland" %% "log4effect" % log4EffectVersion
General mechanism
Logging is done using Logged type class:
import cats.effect.Sync
import io.scalaland.log4effect.Logged
def operation[F[_]: Sync: Logged] = for {
a <- Sync[F].defer(1 + 1)
b <- Sync[F].defer(2 + 2)
_ <- Logged[F].info(s"a = $a b=$b")
} yield a -> b
If you want you can use interpolator syntax - it assumes that there is
cats.Show instance for any value that you use in it.
import cats.implicits._
import io.scalaland.log4effect.Logged
import io.scalaland.log4effect.syntax._
val i = 1
val d = 1.0
val s = "test"
def logs[F[_]: Monad: Logged] = for {
_ <- trace"$i $d $s"[F]
_ <- trace"$i $d $s".withEx[F](new Exception("with ex"))
_ <- debug"$i $d $s"[F]
_ <- debug"$i $d $s".withEx[F](new Exception("with ex"))
_ <- info"$i $d $s"[F]
_ <- info"$i $d $s".withEx[F](new Exception("with ex"))
_ <- warn"$i $d $s"[F]
_ <- warn"$i $d $s".withEx[F](new Exception("with ex"))
_ <- error"$i $d $s"[F]
_ <- error"$i $d $s".withEx[F](new Exception("with ex"))
} yield ()
If there is no cats.Show you'd have to call .toString explicitly.