SAM Type Interface #920

Jay-Lokhande · 2025-06-18T18:26:10Z

This PR's objective is to create a SAM type interface in log4cats

core/shared/src/main/scala/org/typelevel/log4cats/JsonLike.scala

morgen-peschke · 2025-06-19T23:38:21Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+final case class KernelLogLevel(name: String, value: Double) {
+  def namePadded: String = KernelLogLevel.padded(this)
+
+  KernelLogLevel.add(this)
+}


issue (structure): I'm sick right now, but we should get on a call towards the end of next week and go over bincompat.

Case classes are wonderful for applications, but we're going to tend to avoid them because they don't play nicely with bincompat.

agreed 💯

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

morgen-peschke · 2025-06-19T23:40:11Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+  def add(level: KernelLogLevel): Unit = synchronized {
+    val length = level.name.length
+    map += level.name.toLowerCase -> level
+    if (length > maxLength) {
+      maxLength = length
+      padded = map.map { case (_, level) =>
+        level -> level.name.padTo(maxLength, ' ').mkString
+      }
+    } else {
+      padded += level -> level.name.padTo(maxLength, ' ').mkString
+    }
+  }


issue: I'm not convinced we need to support dynamically adding log levels, or looking them up by name.

Reminder to remove the dynamically added log levels

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

morgen-peschke · 2025-06-20T00:36:10Z

core/shared/src/main/scala/org/typelevel/log4cats/LoggerKernel.scala

+  final def logTrace(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Trace, record)
+  final def logDebug(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Debug, record)
+  final def logInfo(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Info, record)
+  final def logWarn(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Warn, record)
+  final def logError(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Error, record)


suggestion (naming): If we do end up needing these, we should simplify down the names

Suggested change

final def logTrace(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Trace, record)

final def logDebug(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Debug, record)

final def logInfo(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Info, record)

final def logWarn(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Warn, record)

final def logError(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Error, record)

final def trace(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Trace, record)

final def debug(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Debug, record)

final def info(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Info, record)

final def warn(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Warn, record)

final def error(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Error, record)

lets keep it until final change, I tried to change as suggested but its giving error due to duplicates

js-console/src/main/scala/org/typelevel/log4cats/console/ConsoleLogger.scala

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

Jay-Lokhande · 2025-06-20T13:15:50Z

Thank you for all the suggestions, I will rework on it

… Logger

morgen-peschke · 2025-07-09T06:44:16Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+  // For Java/legacy interop, if needed (not implicit)
+  val LevelOrdering: Ordering[KernelLogLevel] =
+    Ordering.by[KernelLogLevel, Int](_.value).reverse


todo: Java interop is a non-issue, since attempting to use cats-effect from Java would be painful (at best) and the idioms are all sorts of incompatible.

There's an implicit which provides an Ordering[A] if there is an Order[A] in scope, so this can be removed.

Reminder to remove this

morgen-peschke · 2025-09-28T14:29:52Z

core/shared/src/main/scala/org/typelevel/log4cats/SamStructuredLogger.scala

+      override def error(t: Throwable)(message: => String): F[Unit] = l.error(t)(f(message))
+    }
+
+  private def mapK[G[_], F[_]](f: G ~> F)(logger: SamStructuredLogger[G]): SamStructuredLogger[F] =


suggestion: This is going to need to be overridden in a bunch of Logger subclasses, so you'll probably want to add a .mapK to LoggerKernel

morgen-peschke · 2025-09-28T14:31:02Z

core/shared/src/main/scala/org/typelevel/log4cats/SamStructuredLogger.scala

+  implicit def optionTSamStructuredLogger[F[_]: Functor](implicit
+      ev: SamStructuredLogger[F]
+  ): SamStructuredLogger[OptionT[F, *]] =
+    ev.mapK(OptionT.liftK[F])
+
+  implicit def eitherTSamStructuredLogger[F[_]: Functor, E](implicit
+      ev: SamStructuredLogger[F]
+  ): SamStructuredLogger[EitherT[F, E, *]] =
+    ev.mapK(EitherT.liftK[F, E])
+
+  implicit def kleisliSamStructuredLogger[F[_], A](implicit
+      ev: SamStructuredLogger[F]
+  ): SamStructuredLogger[Kleisli[F, A, *]] =
+    ev.mapK(Kleisli.liftK[F, A])


issue: We really don't want to add implicit conversions for this sort of thing. It leads to really confusing code.

morgen-peschke · 2025-09-28T14:36:56Z

core/shared/src/main/scala/org/typelevel/log4cats/ConsoleLoggerKernel.scala

+      // Use simple timestamp formatting instead of java.time.Instant for Scala Native compatibility
+      val timeStr = s"${new java.util.Date(timestamp).toString}"


cleanup: Scala Native should support Instant, and it's better to avoid the java.util time classes whenever possible.

morgen-peschke · 2025-09-28T14:45:13Z

core/shared/src/test/scala/org/typelevel/log4cats/NoOpLoggerKernelTest.scala

+    val kernel = NoOpLoggerKernel[IO, String]
+    val logger = SamLogger.wrap(kernel)
+    // All of these should be no-ops and not throw
+    logger.info("This should not appear").void *>


issue: This isn't actually testing what the comment hint it's testing.

To do that, you'd need something like this:

private def boom()(implicit loc: munit.Location): String = fail("This code should not have executed")

This would replace the message.

Suggested change

logger.info("This should not appear").void *>

logger.info(boom()).void *>

morgen-peschke · 2025-09-28T14:46:23Z

core/shared/src/test/scala/org/typelevel/log4cats/NoOpLoggerKernelTest.scala

+    // All of these should be no-ops and not throw
+    logger.info("This should not appear").void *>
+      logger.error("This should not appear").void *>
+      logger.warn("This should not appear").void *>


cleanup: logger.warn and friends already return F[Unit], so you don't need to add .void

morgen-peschke · 2025-09-28T14:47:51Z

core/shared/src/test/scala/org/typelevel/log4cats/SamLoggerTest.scala

+import cats.effect.IO
+import munit.CatsEffectSuite
+
+class SamLoggerTest extends CatsEffectSuite {


issue: tests that require you to inspect the console to see if they pass or not aren't automated tests.

They can be useful when doing exploratory programming, but they shouldn't generally be committed to source.

morgen-peschke · 2025-09-28T14:49:02Z

core/shared/src/test/scala/org/typelevel/log4cats/SamStructuredLoggerTest.scala

+  test("SamStructuredLogger should handle context with multiple entries") {
+    var capturedLogs: List[(KernelLogLevel, Log.Builder[String] => Log.Builder[String])] = Nil
+
+    val testKernel = new LoggerKernel[IO, String] {


issue: Instead of inlining this with a var, it'd be better to rework the existing test loggers to use LoggerKernel

…khande/log4cats into feature/log4cats-sam-type

Jay-Lokhande added 12 commits June 18, 2025 15:50

Added Logger Kernel Initial File

485b98b

sbt scalafmt

8d8223f

added withMethodName method

f6e9d55

added more SAM type specific files

e7f0be4

changed LogLevel to remove conflict

7f6dc0e

going back to LogLevel name

9c3c243

original WriterTLogger

9908c00

deleted DefferedLogLevel

4fb2850

build.sbt

fc58670

scalafmt

23b2094

sbt scalafmtSbt

3f1f34c

added KernelLogLevel

7961c15

morgen-peschke reviewed Jun 20, 2025

View reviewed changes

iRevive mentioned this pull request Jun 20, 2025

Logs module typelevel/otel4s#994

Closed

15 tasks

add new samlogger interface based on old and poc logger

a5708c3

Jay-Lokhande added 7 commits June 23, 2025 07:15

add SamStructuredLogger that delegates to LoggerKernel, with original…

649468d

… Logger

modify log with parameterized with the context type

ac5aaee

change datatype double to int and use cats Order

53dda4f

update LoggerKernel to use new Log.scala

634de7d

update LogRecord and Recordable to use paramerterized Log

b7f0d10

update ConsoleLogger to original, JsonLike

859753b

remove unused Context.Encoder

ac1a39b

lenguyenthanh mentioned this pull request Jun 30, 2025

Allow adding effect's contextual environment to the log context #800

Open

morgen-peschke reviewed Jul 9, 2025

View reviewed changes

Jay-Lokhande and others added 5 commits August 7, 2025 18:09

Merge branch 'typelevel:main' into feature/log4cats-sam-type

3beb5f7

remove JsonLike Structure instead bypass it direct

44ab02b

modify files to adapt new change

10b0c81

update log.scala

4b746e2

update recordable

2ad479c

morgen-peschke reviewed Sep 28, 2025

View reviewed changes

Jay-Lokhande and others added 23 commits October 4, 2025 06:57

remove LogRecord Recordable and SamLoggerAdapter

bd68364

update core's extras

d19ffae

update old interfaces with logger kernel functionality

749fd3d

remove SamLoggerAdaptorTest

72376e8

update sam implementation after removing LogRecor and Recordable

b0ddff1

update test suite

58f2b51

update js-console ConsoleLogger

b606c3b

update slf4j Logger Internel

6962ff8

update testing module with LoggerKernel

041375c

update NoOp Logger

468114f

Merge branch 'typelevel:main' into feature/log4cats-sam-type

cb28f49

Merge branch 'feature/log4cats-sam-type' of https://github.com/Jay-Lo…

f695de3

…khande/log4cats into feature/log4cats-sam-type

fix match level error

f6bf9a3

fix match error

329bc40

fix match error

a32d908

fir test errors

809e560

try differentt fix

1b7aeb9

fix tests

2a9fe26

sbt scala format

3a13966

update mima Binary issues

0f8c152

add MiMa Exclusions

21b3e6c

remove sourcecode

e69b27d

remove java.util time class as suggested

8bbf794

		// Use simple timestamp formatting instead of java.time.Instant for Scala Native compatibility
		val timeStr = s"${new java.util.Date(timestamp).toString}"

	logger.info("This should not appear").void *>
	logger.info(boom()).void *>

SAM Type Interface #920

Are you sure you want to change the base?

SAM Type Interface #920

Uh oh!

Conversation

Jay-Lokhande commented Jun 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Jay-Lokhande commented Jun 20, 2025

Uh oh!

morgen-peschke Jul 9, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

morgen-peschke Sep 28, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

morgen-peschke Sep 28, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Jay-Lokhande commented Jun 18, 2025 •

edited

Loading

morgen-peschke Jul 9, 2025 •

edited

Loading

morgen-peschke Sep 28, 2025 •

edited

Loading

morgen-peschke Sep 28, 2025 •

edited

Loading