fix: remove implicit val causing conflicts with parsing cli arguments

src/main/wacc/Main.scala

@@ -18,7 +18,7 @@ import org.typelevel.log4cats.slf4j.Slf4jLogger
 import org.typelevel.log4cats.Logger
 
 import assemblyIR as asm
-import java.nio.file.Paths
+import cats.data.ValidatedNel
 
 /*
 TODO:
@@ -30,34 +30,30 @@ TODO:
   6) errors can be handled more gracefully probably
  */
 
-given Argument[Path] = Argument.from("path") { str =>
-  val path =
-    if (str.startsWith("~")) Paths.get(System.getProperty("user.home"), str.drop(1)) // Expand ~
-    else Paths.get(str).toAbsolutePath.normalize() // TODO: normalize or not?
-
-  if (path.toString.endsWith(".wacc")) {
-    (
-      Either.cond(Files.exists(path), path, s"File '${path.toAbsolutePath}' does not exist"),
-      Either.cond(
-        Files.isRegularFile(path),
-        path,
-        s"File '${path.toAbsolutePath}' must be a regular file"
-      )
-    ).mapN((_, _) => path).toValidatedNel
-  } else {
-    Right(path).toValidatedNel
-  }
-}
-
 given logger: Logger[IO] = Slf4jLogger.getLogger[IO]
 
 val logOpt: Opts[Boolean] =
   Opts.flag("log", "Enable logging for additional compilation details", short = "l").orFalse
 
-val outputOpt: Opts[Option[Path]] =
+def validateFile(path: Path): ValidatedNel[String, Path] = {
-  Opts.option[Path]("output", "Specify path for output assembly file(s)").orNone
+  (for {
+    // TODO: redundant 2nd parameter :(
+    _ <- Either.cond(Files.exists(path), (), s"File '${path}' does not exist")
+    _ <- Either.cond(Files.isRegularFile(path), (), s"File '${path}' must be a regular file")
+    _ <- Either.cond(path.toString.endsWith(".wacc"), (), "File must have .wacc extension")
+  } yield path).toValidatedNel
+}
 
-val filesOpt: Opts[NonEmptyList[Path]] = Opts.arguments[Path]("files")
+val filesOpt: Opts[NonEmptyList[Path]] =
+  Opts.arguments[Path]("files").mapValidated {
+    _.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
 
 def frontend(
     contents: String