Rewrite to Scala 3 syntax using -rewrite flag

build.sbt

@@ -49,9 +49,6 @@ Compile / resourceGenerators += Def.task {
 }
 
 /* sbt-assembly configuration: build an executable jar. */
-//assembly / assemblyOption  := (assembly / assemblyOption).value.copy(
-//    prependShellScript = Some(sbtassembly.AssemblyPlugin.defaultShellScript)
-//)
 ThisBuild / assemblyPrependShellScript := Some(sbtassembly.AssemblyPlugin.defaultShellScript)
 assembly / assemblyJarName := "fuse.jar"
 assembly / test := {}

src/main/scala/Compiler.scala

@@ -9,7 +9,7 @@ import Configuration._
 import Syntax._
 import Transformer.{PartialTransformer, TypedPartialTransformer}
 
-object Compiler {
+object Compiler:
 
   // Transformers to execute *before* type checking.
   val preTransformers: List[(String, PartialTransformer)] = List(
@@ -28,28 +28,25 @@ object Compiler {
       "Add bitwidth" -> (passes.AddBitWidth, true)
     )
 
-  def showDebug(ast: Prog, pass: String, c: Config): Unit = {
-    if c.passDebug then {
+  def showDebug(ast: Prog, pass: String, c: Config): Unit =
+    if c.passDebug then
       val top = ("=" * 15) + pass + ("=" * 15)
       println(top)
       println(Pretty.emitProg(ast)(c.logLevel == scribe.Level.Debug).trim)
       println("=" * top.length)
-    }
-  }
 
-  def toBackend(str: BackendOption): fuselang.backend.Backend = str match {
+  def toBackend(str: BackendOption): fuselang.backend.Backend = str match
     case Vivado => backend.VivadoBackend
     case Cpp => backend.CppRunnable
     case Calyx => backend.calyx.CalyxBackend
-  }
 
-  def checkStringWithError(prog: String, c: Config = emptyConf) = {
+  def checkStringWithError(prog: String, c: Config = emptyConf) =
     val preAst = Parser(prog).parse()
 
     showDebug(preAst, "Original", c)
 
     // Run pre transformers if lowering is enabled
-    val ast = if c.enableLowering then {
+    val ast = if c.enableLowering then
       preTransformers.foldLeft(preAst)({
         case (ast, (name, pass)) => {
           val newAst = pass.rewrite(ast)
@@ -70,9 +67,8 @@ object Compiler {
           } */
         }
       })
-    } else {
+    else
       preAst
-    }
     passes.WellFormedChecker.check(ast)
     typechecker.TypeChecker.typeCheck(ast);
     showDebug(ast, "Type Checking", c)
@@ -83,9 +79,8 @@ object Compiler {
     showDebug(ast, "Capability Checking", c)
     typechecker.AffineChecker.check(ast); // Doesn't modify the AST
     ast
-  }
 
-  def codegen(ast: Prog, c: Config = emptyConf) = {
+  def codegen(ast: Prog, c: Config = emptyConf) =
     // Filter out transformers not running in this mode
     val toRun = postTransformers.filter({
       case (_, (_, onlyLower)) => {
@@ -101,14 +96,12 @@ object Compiler {
       }
     })
     toBackend(c.backend).emit(transformedAst, c)
-  }
 
   // Outputs red text to the console
-  def red(txt: String): String = {
+  def red(txt: String): String =
     Console.RED + txt + Console.RESET
-  }
 
-  def compileString(prog: String, c: Config): Either[String, String] = {
+  def compileString(prog: String, c: Config): Either[String, String] =
     Try(codegen(checkStringWithError(prog, c), c)).toEither.left
       .map(err => {
         scribe.info(err.getStackTrace().take(10).mkString("\n"))
@@ -136,13 +129,12 @@ object Compiler {
         val commentPre = toBackend(c.backend).commentPrefix
         s"$commentPre $meta\n" + out
       })
-  }
 
   def compileStringToFile(
       prog: String,
       c: Config,
       out: String
-  ): Either[String, Path] = {
+  ): Either[String, Path] =
 
     compileString(prog, c).map(p => {
       Files.write(
@@ -153,6 +145,4 @@ object Compiler {
         StandardOpenOption.WRITE
       )
     })
-  }
 
-}

src/main/scala/GenerateExec.scala

@@ -10,7 +10,7 @@ import common.CompilerError.HeaderMissing
   * Provides utilities to compile a program and link it with headers required
   * by the CppRunnable backend.
   */
-object GenerateExec {
+object GenerateExec:
   // TODO(rachit): Move this to build.sbt
   val headers = List("parser.cpp", "json.hpp")
 
@@ -19,18 +19,18 @@ object GenerateExec {
 
 
   // Not the compiler directory, check if the fallback directory has been setup.
-  if Files.exists(headerLocation) == false then {
+  if Files.exists(headerLocation) == false then
     // Fallback for headers not setup. Unpack headers from JAR file.
     headerLocation = headerFallbackLocation
 
-    if Files.exists(headerFallbackLocation) == false then {
+    if Files.exists(headerFallbackLocation) == false then
       scribe.warn(
         s"Missing headers required for `fuse run`." +
           s" Unpacking from JAR file into $headerFallbackLocation."
       )
 
       val dir = Files.createDirectory(headerFallbackLocation)
-      for header <- headers do {
+      for header <- headers do
         val stream = getClass.getResourceAsStream(s"/headers/$header")
         val hdrSource = Source.fromInputStream(stream).toArray.map(_.toByte)
         Files.write(
@@ -39,9 +39,6 @@ object GenerateExec {
           StandardOpenOption.CREATE_NEW,
           StandardOpenOption.WRITE
         )
-      }
-    }
-  }
 
   /**
     * Generates an executable object [[out]]. Assumes that [[src]] is a valid
@@ -54,14 +51,12 @@ object GenerateExec {
       src: Path,
       out: String,
       compilerOpts: List[String]
-  ): Either[String, Int] = {
+  ): Either[String, Int] =
 
     // Make sure all headers are downloaded.
-    for header <- headers do {
-      if Files.exists(headerLocation.resolve(header)) == false then {
+    for header <- headers do
+      if Files.exists(headerLocation.resolve(header)) == false then
         throw HeaderMissing(header, headerLocation.toString)
-      }
-    }
 
     val CXX =
       Seq("g++", "-g", "--std=c++14", "-Wall", "-I", headerLocation.toString) ++ compilerOpts
@@ -75,10 +70,7 @@ object GenerateExec {
     scribe.info(cmd.mkString(" "))
     val status = cmd ! logger
 
-    if status != 0 then {
+    if status != 0 then
       Left(s"Failed to generate the executable $out.\n${stderr}")
-    } else {
+    else
       Right(status)
-    }
-  }
-}

src/main/scala/Main.scala

@@ -31,7 +31,7 @@ object Main:
     })
     .toMap
 
-  val parser = new scopt.OptionParser[Config]("fuse") {
+  val parser = new scopt.OptionParser[Config]("fuse"):
 
     head(s"Dahlia (sha = ${meta("git.hash")}, status = ${meta("git.status")})")
 
@@ -112,16 +112,14 @@ object Main:
           .action((f, c) => c.copy(output = Some(f)))
           .text("Name of the output artifact.")
       )
-  }
 
   def runWithConfig(conf: Config): Either[String, Int] =
     type ErrString = String
 
     val path = conf.srcFile.toPath
-    val prog = Files.exists(path) match {
+    val prog = Files.exists(path) match
       case true => Right(new String(Files.readAllBytes(path)))
       case false => Left(s"$path: No such file in working directory")
-    }
 
     val cppPath: Either[ErrString, Option[Path]] = prog.flatMap(prog =>
       conf.output match {

src/main/scala/Utils.scala

@@ -2,70 +2,57 @@ package fuselang
 import scala.{PartialFunction => PF}
 import scala.math.{log10, ceil}
 
-object Utils {
+object Utils:
 
-  implicit class RichOption[A](opt: => Option[A]) {
-    def getOrThrow[T <: Throwable](except: T) = opt match {
+  implicit class RichOption[A](opt: => Option[A]):
+    def getOrThrow[T <: Throwable](except: T) = opt match
       case Some(v) => v
       case None => throw except
-    }
-  }
 
   // https://codereview.stackexchange.com/questions/14561/matching-bigints-in-scala
   // TODO: This can overflow and result in an runtime exception
-  object Big {
+  object Big:
     def unapply(n: BigInt) = Some(n.toInt)
-  }
 
-  def bitsNeeded(n: Int): Int = n match {
+  def bitsNeeded(n: Int): Int = n match
     case 0 => 1
     case n if n > 0 => ceil(log10(n + 1) / log10(2)).toInt
     case n if n < 0 => bitsNeeded(n.abs) + 1
-  }
 
-  def bitsNeeded(n: BigInt): Int = n match {
+  def bitsNeeded(n: BigInt): Int = n match
     case Big(0) => 1
     case n if n > 0 => ceil(log10((n + 1).toDouble) / log10(2)).toInt
     case n if n < 0 => bitsNeeded(n.abs) + 1
-  }
 
-  def cartesianProduct[T](llst: Seq[Seq[T]]): Seq[Seq[T]] = {
+  def cartesianProduct[T](llst: Seq[Seq[T]]): Seq[Seq[T]] =
     def pel(e: T, ll: Seq[Seq[T]], a: Seq[Seq[T]] = Nil): Seq[Seq[T]] =
-      ll match {
+      ll match
         case Nil => a.reverse
         case x +: xs => pel(e, xs, (e +: x) +: a)
-      }
 
-    llst match {
+    llst match
       case Nil => Nil
       case x +: Nil => x.map(Seq(_))
       case x +: _ =>
-        x match {
+        x match
           case Nil => Nil
           case _ =>
             llst
               .foldRight(Seq(x))((l, a) => l.flatMap(x => pel(x, a)))
               .map(_.dropRight(x.size))
-        }
-    }
-  }
 
 
-  @inline def asPartial[A, B, C](f: (A, B) => C): PF[(A, B), C] = {
+  @inline def asPartial[A, B, C](f: (A, B) => C): PF[(A, B), C] =
     case (a, b) => f(a, b)
-  }
 
-  @inline def assertOrThrow[T <: Throwable](cond: Boolean, except: => T) = {
+  @inline def assertOrThrow[T <: Throwable](cond: Boolean, except: => T) =
     if !cond then throw except
-  }
 
   @deprecated(
     "pr is used for debugging. Remove all call to it before committing",
     "fuse 0.0.1"
   )
-  @inline def pr[T](v: T) = {
+  @inline def pr[T](v: T) =
     println(v)
     v
-  }
 
-}

src/main/scala/backends/Backend.scala

@@ -6,14 +6,12 @@ import CompilerError.BackendError
 /**
   * Abstract definition of a Fuse backend.
   */
-trait Backend {
+trait Backend:
 
-  def emit(p: Syntax.Prog, c: Configuration.Config): String = {
-    if c.header && (canGenerateHeader == false) then {
+  def emit(p: Syntax.Prog, c: Configuration.Config): String =
+    if c.header && (canGenerateHeader == false) then
       throw BackendError(s"Backend $this does not support header generation.")
-    }
     emitProg(p, c)
-  }
 
   /**
     * Generate a String representation of the Abstract Syntax Tree of the
@@ -32,4 +30,3 @@ trait Backend {
     */
   val commentPrefix: String = "//"
 
-}