feat: introduction of logger to eliminate printstreams

project.scala

@@ -9,6 +9,8 @@
 //> using dep org.typelevel::cats-effect::3.5.7
 //> using dep com.monovore::decline::2.5.0
 //> using dep com.monovore::decline-effect::2.5.0
+//> using dep org.typelevel::log4cats-slf4j::2.7.0
+//> using dep org.slf4j:slf4j-simple:2.0.17
 //> using test.dep org.scalatest::scalatest::3.2.19
 //> using dep org.typelevel::cats-effect-testing-scalatest::1.6.0
 

src/main/wacc/Main.scala

@@ -4,7 +4,6 @@ import scala.collection.mutable
 import cats.data.Chain
 import parsley.{Failure, Success}
 import java.io.File
-import java.io.PrintStream
 import cats.implicits.*
 
 import cats.effect.IO
@@ -14,6 +13,9 @@ import com.monovore.decline._
 import com.monovore.decline.effect._
 import com.monovore.decline.Argument
 
+import org.typelevel.log4cats.slf4j.Slf4jLogger
+import org.typelevel.log4cats.Logger
+
 import assemblyIR as asm
 
 given Argument[File] = Argument.from("file") { str =>
@@ -32,30 +34,33 @@ val cliCommand: Command[File] =
     Opts.argument[File]("file")
   }
 
+given logger: Logger[IO] = Slf4jLogger.getLogger[IO]
+
 def frontend(
     contents: String
-)(using stdout: PrintStream): IO[Either[Int, microWacc.Program]] = {
-  IO(parser.parse(contents)).map {
+): IO[Either[Int, microWacc.Program]] = {
+  IO(parser.parse(contents)).flatMap {
     case Failure(msg) =>
-      stdout.println(msg)
-      Left(100) // Syntax error
+      logger.error(s"Syntax error: $msg").as(Left(100))
 
     case Success(prog) =>
       given errors: mutable.Builder[Error, List[Error]] = List.newBuilder
-      given errorContent: String = contents
 
       val (names, funcs) = renamer.rename(prog)
       given ctx: typeChecker.TypeCheckerCtx = typeChecker.TypeCheckerCtx(names, funcs, errors)
 
       val typedProg = typeChecker.check(prog)
 
-      if (errors.result.isEmpty) Right(typedProg)
+      if (errors.result.isEmpty) IO.pure(Right(typedProg))
       else {
-        errors.result.foreach(printError)
-        Left(errors.result.view.map {
+        val exitCode = errors.result.view.map {
           case _: Error.InternalError => 201
           case _                      => 200
-        }.max)
+        }.max
+
+        logger.error(s"Semantic errors:\n${errors.result.mkString("\n")}") *> IO.pure(
+          Left(exitCode)
+        )
       }
   }
 }
@@ -64,21 +69,18 @@ val s = "enter an integer to echo"
 def backend(typedProg: microWacc.Program): Chain[asm.AsmLine] =
   asmGenerator.generateAsm(typedProg)
 
-def compile(filename: String, outFile: Option[File] = None)(using
-    stdout: PrintStream = Console.out
-): IO[Int] =
+def compile(filename: String, outFile: Option[File] = None): IO[Int] =
   for {
     contents <- IO(os.read(os.Path(filename)))
+    _ <- logger.info(s"Compiling file: $filename")
     result <- frontend(contents)
     exitCode <- result.fold(
-      IO.pure, // Return error code (handles Left case)
+      code => logger.error(s"Compilation failed for $filename\nExit code: $code").as(code),
       typedProg =>
-        IO {
-          writer.writeTo(
-            backend(typedProg),
-            PrintStream(outFile.getOrElse(File(filename.stripSuffix(".wacc") + ".s")))
-          )
-        }.as(0) // Compilation succeeded
+        val outputFile = outFile.getOrElse(File(filename.stripSuffix(".wacc") + ".s"))
+        writer.writeTo(backend(typedProg), outputFile) *> logger
+          .info(s"Compilation succeeded: $filename")
+          .as(0)
     )
   } yield exitCode
 

src/main/wacc/backend/writer.scala

@@ -1,12 +1,27 @@
 package wacc
 
-import java.io.PrintStream
+import cats.effect.Resource
+import java.nio.charset.StandardCharsets
+import java.io.File
+import java.io.BufferedWriter
+import java.io.FileWriter
 import cats.data.Chain
+import cats.effect.IO
+
+import org.typelevel.log4cats.Logger
 
 object writer {
   import assemblyIR._
 
-  def writeTo(asmList: Chain[AsmLine], printStream: PrintStream): Unit = {
-    asmList.iterator.foreach(printStream.println)
-  }
+  def writeTo(asmList: Chain[AsmLine], outputFile: File)(using logger: Logger[IO]): IO[Unit] =
+    Resource
+      .fromAutoCloseable {
+        IO(BufferedWriter(FileWriter(outputFile, StandardCharsets.UTF_8)))
+      }
+      .use { writer =>
+        IO {
+          asmList.iterator.foreach(line => writer.write(line.toString + "\n"))
+          writer.flush() // TODO: NECESSARY OR NOT?
+        } *> logger.info(s"Wrote assembly to ${outputFile.getAbsolutePath}")
+      }
 }

src/test/wacc/examples.scala

@@ -7,7 +7,6 @@ import org.scalatest.freespec.AsyncFreeSpec
 import cats.effect.testing.scalatest.AsyncIOSpec
 import java.io.File
 import sys.process._
-import java.io.PrintStream
 import scala.io.Source
 import cats.effect.IO
 import wacc.{compile as compileWacc}
@@ -30,7 +29,6 @@ class ParallelExamplesSpec extends AsyncFreeSpec with AsyncIOSpec with BeforeAnd
 
   forEvery(files) { (filename, expectedResult) =>
     val baseFilename = filename.stripSuffix(".wacc")
-    given stdout: PrintStream = PrintStream(File(baseFilename + ".out"))
 
     s"$filename" - {
       "should be compiled with correct result" in {