diff --git a/src/main/wacc/Main.scala b/src/main/wacc/Main.scala
index 571103b..33c4fef 100644
--- a/src/main/wacc/Main.scala
+++ b/src/main/wacc/Main.scala
@@ -23,11 +23,10 @@ import cats.data.ValidatedNel
 /*
 TODO:
   1) IO correctness
-  2)  --greedy,
-  3) parallelised compilation
-  4) splitting the file up and nicer refactoring
-  5) logging could be removed
-  6) errors can be handled more gracefully probably
+  2) Errors can be handled more gracefully - currently, parallelised compilation is not fail fast as far as I am aware
+  3) splitting the file up and nicer refactoring
+  4) logging could be removed
+  5) general cleanup and comments (things like replacing home/<user> with ~ , and names of parameters and args, descriptions etc)
  */
 
 given logger: Logger[IO] = Slf4jLogger.getLogger[IO]
@@ -49,12 +48,14 @@ val filesOpt: Opts[NonEmptyList[Path]] =
     _.traverse(validateFile)
   }
 
-// TODO: Is intermediate String necessary
 val outputOpt: Opts[Option[Path]] =
   Opts
     .option[Path]("output", metavar = "path", help = "Output directory for compiled files.")
     .orNone
 
+val greedyOpt: Opts[Boolean] =
+  Opts.flag("greedy", "Compile WACC files sequentially instead of parallelly", short = "g").orFalse
+
 def frontend(
     contents: String
 ): IO[Either[Int, microWacc.Program]] = {
@@ -138,27 +139,43 @@ def compile(filePath: Path, outputDir: Option[Path], log: Boolean): IO[Int] = {
   } yield exitCode
 }
 
-// TODO: this is sequential, thus should be what occurs when --greedy is passed in
-val compileCommand: Opts[IO[ExitCode]] =
-  (filesOpt, logOpt, outputOpt).mapN { (files, log, outDir) =>
-    files
-      .traverse { file =>
-        compile(file.toAbsolutePath, outDir, log).handleErrorWith { err =>
-          // TODO: probably a more elegant way of doing this
-          // also, -1 arbitrary
-          // also - this outputs two messages for some reason
-          logger.error(err.getMessage) // *> IO.pure(ExitCode(-1))
-        }
+// TODO: Remove duplicate code between compileCommandSequential and compileCommandParallel
+def compileCommandSequential(
+    files: NonEmptyList[Path],
+    log: Boolean,
+    outDir: Option[Path]
+): IO[ExitCode] =
+  files
+    .traverse { file =>
+      compile(file.toAbsolutePath, outDir, log).handleErrorWith { err =>
+        // TODO: probably a more elegant way of doing this
+        // also, -1 arbitrary
+        // also - this outputs two messages for some reason
+        logger.error(err.getMessage) // *> IO.raiseError(err)
       }
-      .map { exitCodes =>
-        if (exitCodes.exists(_ != 0))
-          ExitCode.Error // TODO- it should be the first one to exit when parallelised :)
-        else ExitCode.Success
+    }
+    .map { exitCodes =>
+      if (exitCodes.exists(_ != 0)) ExitCode.Error else ExitCode.Success
+    }
+
+def compileCommandParallel(
+    files: NonEmptyList[Path],
+    log: Boolean,
+    outDir: Option[Path]
+): IO[ExitCode] =
+  files
+    .parTraverse { file =>
+      compile(file.toAbsolutePath, outDir, log).handleErrorWith { err =>
+        // TODO: probably a more elegant way of doing this
+        // also, -1 arbitrary
+        // also - this outputs two messages for some reason
+        logger.error(err.getMessage) // *> IO.raiseError(err)
       }
+    }
+    .map { exitCodes =>
+      if (exitCodes.exists(_ != 0)) ExitCode.Error else ExitCode.Success
+    }
 
-  }
-
-// TODO: add parallelisable option
 object Main
     extends CommandIOApp(
       name = "wacc",
@@ -166,6 +183,9 @@ object Main
       version = "1.0"
     ) {
   def main: Opts[IO[ExitCode]] =
-    compileCommand
+    (greedyOpt, filesOpt, logOpt, outputOpt).mapN { (greedy, files, log, outDir) =>
+      if (greedy) compileCommandSequential(files, log, outDir)
+      else compileCommandParallel(files, log, outDir)
+    }
 
 }