diff --git a/src/main/kotlin/runner/jvm/JVMRunner.kt b/src/main/kotlin/runner/jvm/JVMRunner.kt
index 97f5745..7db075c 100644
--- a/src/main/kotlin/runner/jvm/JVMRunner.kt
+++ b/src/main/kotlin/runner/jvm/JVMRunner.kt
@@ -13,6 +13,7 @@ import runner.Runner
 import technology.idlab.parser.intermediate.IRArgument
 import technology.idlab.parser.intermediate.IRParameter
 import technology.idlab.parser.intermediate.IRStage
+import technology.idlab.runner.jvm.Arguments
 import technology.idlab.util.Log
 import technology.idlab.util.Log.Cause.*
 
@@ -42,8 +43,9 @@ class JVMRunner(
     val arguments = this.instantiate(stage.processor.parameters.zip(stage.arguments))
 
     /** Initialize the stage with the new map. */
-    val constructor = clazz.getConstructor(Map::class.java)
-    this.stages[stage.uri] = constructor.newInstance(arguments) as Processor
+    val constructor = clazz.getConstructor(Arguments::class.java)
+    val args = Arguments.from(arguments)
+    this.stages[stage.uri] = constructor.newInstance(args) as Processor
   }
 
   override suspend fun exec() = coroutineScope {
@@ -86,7 +88,7 @@ class JVMRunner(
 
   private fun instantiate(
       serialized: Map<String, Pair<IRParameter, IRArgument>>
-  ): Map<String, Any> {
+  ): Map<String, List<Any>> {
     return serialized.mapValues { (_, map) ->
       val (parameter, arguments) = map
 
diff --git a/src/main/kotlin/runner/jvm/Processor.kt b/src/main/kotlin/runner/jvm/Processor.kt
index 6afa58b..ba80e42 100644
--- a/src/main/kotlin/runner/jvm/Processor.kt
+++ b/src/main/kotlin/runner/jvm/Processor.kt
@@ -1,6 +1,6 @@
 package runner.jvm
 
-import java.util.Optional
+import technology.idlab.runner.jvm.Arguments
 import technology.idlab.util.Log
 
 abstract class Processor(
@@ -8,7 +8,7 @@ abstract class Processor(
      * The arguments of a processor are stored in a map and can be accessed by name. At the time of
      * writing, the user must manually cast the arguments to the correct type.
      */
-    private val arguments: Map<String, Any>,
+    protected val arguments: Arguments,
 ) {
   /**
    * Processors which wish to log messages should use the logger provided by the template class.
@@ -16,25 +16,5 @@ abstract class Processor(
    */
   @JvmField protected val log = Log.shared
 
-  fun <T> getArgument(name: String): T {
-    val result = arguments.get(name) as List<T> ?: log.fatal("Argument $name is missing")
-    return result.get(0) ?: log.fatal("Argument $name is missing")
-  }
-
-  fun <T> getNullableArgument(name: String): T? {
-    val result = arguments.get(name) as List<T>?
-    return result?.get(0)
-  }
-
-  fun <T> getOptionalArgument(name: String): Optional<T> {
-    val result = (arguments.get(name) as List<T>?)?.get(0) ?: log.fatal("Argument $name is missing")
-
-    if (result is Optional<*>) {
-      return result as Optional<T>
-    }
-
-    log.fatal("Argument $name is not optional")
-  }
-
   abstract suspend fun exec()
 }
diff --git a/src/main/kotlin/std/FileReader.kt b/src/main/kotlin/std/FileReader.kt
index 2f879d4..0b14b2d 100644
--- a/src/main/kotlin/std/FileReader.kt
+++ b/src/main/kotlin/std/FileReader.kt
@@ -3,11 +3,12 @@ package technology.idlab.std
 import java.io.File
 import runner.jvm.Processor
 import runner.jvm.Writer
+import technology.idlab.runner.jvm.Arguments
 
-class FileReader(args: Map<String, Any>) : Processor(args) {
+class FileReader(args: Arguments) : Processor(args) {
   /** Arguments */
-  private val path: String = this.getArgument("path")
-  private val output: Writer = this.getArgument("output")
+  private val path: String = arguments["path"]
+  private val output: Writer = arguments["output"]
 
   /** Read the file as a single byte array and push it down the pipeline. */
   override suspend fun exec() {
diff --git a/src/main/kotlin/std/FileWriter.kt b/src/main/kotlin/std/FileWriter.kt
index f956f18..c2b62e0 100644
--- a/src/main/kotlin/std/FileWriter.kt
+++ b/src/main/kotlin/std/FileWriter.kt
@@ -3,31 +3,33 @@ package technology.idlab.std
 import java.io.File
 import runner.jvm.Processor
 import runner.jvm.Reader
+import technology.idlab.runner.jvm.Arguments
 
-class FileWriter(args: Map<String, Any>) : Processor(args) {
+class FileWriter(args: Arguments) : Processor(args) {
   /** Processor default values. */
   private val overwriteDefault = true
   private val appendDefault = false
 
   /** Arguments */
-  private val file = File(this.getArgument<String>("path"))
-  private val input: Reader = this.getArgument("input")
-  private val overwrite = this.getOptionalArgument<Boolean>("overwrite")
-  private val append = this.getOptionalArgument<Boolean>("append")
+  private val path: String = arguments["path"]
+  private val file = File(path)
+  private val input: Reader = arguments["input"]
+  private val overwrite: Boolean? = arguments["overwrite"]
+  private val append: Boolean? = arguments["append"]
 
   init {
     // Sanity check.
-    if (overwrite.orElse(false) && append.orElse(false)) {
+    if (overwrite == true && append == true) {
       log.fatal("Cannot overwrite and append at the same time")
     }
 
     // Do not overwrite the file if it exists.
-    if (file.exists() && !overwrite.orElse(overwriteDefault)) {
+    if (file.exists() && !(overwrite ?: overwriteDefault)) {
       log.fatal("File ${file.path} already exists")
     }
 
     // Overwrite file if not exists.
-    if (file.exists() && !append.orElse(appendDefault)) {
+    if (file.exists() && !(append ?: appendDefault)) {
       file.writeBytes(ByteArray(0))
     }
   }
diff --git a/src/main/kotlin/std/HttpFetch.kt b/src/main/kotlin/std/HttpFetch.kt
index 20b96b2..59bb639 100644
--- a/src/main/kotlin/std/HttpFetch.kt
+++ b/src/main/kotlin/std/HttpFetch.kt
@@ -8,16 +8,17 @@ import io.ktor.client.statement.*
 import io.ktor.http.*
 import runner.jvm.Processor
 import runner.jvm.Writer
+import technology.idlab.runner.jvm.Arguments
 
-class HttpFetch(args: Map<String, Any>) : Processor(args) {
+class HttpFetch(args: Arguments) : Processor(args) {
   /** Meta configuration. */
   private var engine: HttpClientEngine = CIO.create()
 
   /** Parameters. */
-  private val endpoint = this.getArgument<String>("endpoint")
-  private val output = this.getArgument<Writer>("output")
-  private val headers = this.getArgument<Array<String>>("headers")
-  private val method = this.getNullableArgument<String>("method") ?: "GET"
+  private val endpoint: String = arguments["endpoint"]
+  private val output: Writer = arguments["output"]
+  private val headers: Array<String> = arguments["headers"]
+  private val method: String = arguments.get<String?>("method") ?: "GET"
 
   /** Prebuild request. */
   private val builder = HttpRequestBuilder()
diff --git a/src/main/kotlin/std/RDFValidator.kt b/src/main/kotlin/std/RDFValidator.kt
index ce8700c..f4083e3 100644
--- a/src/main/kotlin/std/RDFValidator.kt
+++ b/src/main/kotlin/std/RDFValidator.kt
@@ -10,18 +10,19 @@ import runner.jvm.Processor
 import runner.jvm.Reader
 import runner.jvm.Writer
 import technology.idlab.extensions.readModelRecursively
+import technology.idlab.runner.jvm.Arguments
 import technology.idlab.util.Log
 
-class RDFValidator(args: Map<String, Any>) : Processor(args) {
+class RDFValidator(args: Arguments) : Processor(args) {
   /** Default values. */
   private val errorIsFatalDefault = false
   private val printReportDefault = false
 
   /** Arguments. */
-  private val errorIsFatal = this.getOptionalArgument<Boolean>("error_is_fatal")
-  private val printReport = this.getOptionalArgument<Boolean>("print_report")
-  private val input = this.getArgument<Reader>("input")
-  private val output = this.getArgument<Writer>("output")
+  private val errorIsFatal: Boolean? = arguments["error_is_fatal"]
+  private val printReport: Boolean? = arguments["print_report"]
+  private val input: Reader = arguments["input"]
+  private val output: Writer = arguments["output"]
 
   /** Runtime fields. */
   private val shapes: Graph
@@ -30,7 +31,7 @@ class RDFValidator(args: Map<String, Any>) : Processor(args) {
 
   // Initialize the shape graph and validator.
   init {
-    val path = this.getArgument<String>("shapes")
+    val path: String = arguments["shapes"]
     val file = File(path)
 
     val shapesModel =
@@ -65,14 +66,14 @@ class RDFValidator(args: Map<String, Any>) : Processor(args) {
         output.push(res)
       } else {
         // Print the report if required.
-        if (printReport.orElse(printReportDefault)) {
+        if (printReport ?: printReportDefault) {
           val out = ByteArrayOutputStream()
           report.model.write(out, "TURTLE")
           Log.shared.info(out.toString())
         }
 
         // Check if we can continue after an error.
-        if (errorIsFatal.orElse(errorIsFatalDefault)) {
+        if (errorIsFatal ?: errorIsFatalDefault) {
           Log.shared.fatal("Validation error is fatal.")
         }
       }
diff --git a/src/main/kotlin/std/Transparent.kt b/src/main/kotlin/std/Transparent.kt
index a8cca73..d517598 100644
--- a/src/main/kotlin/std/Transparent.kt
+++ b/src/main/kotlin/std/Transparent.kt
@@ -3,10 +3,11 @@ package technology.idlab.std
 import runner.jvm.Processor
 import runner.jvm.Reader
 import runner.jvm.Writer
+import technology.idlab.runner.jvm.Arguments
 
-class Transparent(args: Map<String, Any>) : Processor(args) {
-  private val input = this.getArgument<Reader>("input")
-  private val output = this.getArgument<Writer>("output")
+class Transparent(args: Arguments) : Processor(args) {
+  private val input: Reader = arguments["input"]
+  private val output: Writer = arguments["output"]
 
   override suspend fun exec() {
     output.push(input.read())
diff --git a/src/test/kotlin/processors/TappedReader.kt b/src/test/kotlin/processors/TappedReader.kt
index 3c19bb2..0b3a168 100644
--- a/src/test/kotlin/processors/TappedReader.kt
+++ b/src/test/kotlin/processors/TappedReader.kt
@@ -8,15 +8,16 @@ import technology.idlab.parser.intermediate.IRArgument
 import technology.idlab.parser.intermediate.IRParameter
 import technology.idlab.parser.intermediate.IRProcessor
 import technology.idlab.parser.intermediate.IRStage
+import technology.idlab.runner.jvm.Arguments
 
 /**
  * The TappedReader processor provides a convenient way to read data from the pipeline during
  * testing. All incoming data will be written to a global channel, which can be used directly during
  * testing to read data from.
  */
-class TappedReader(args: Map<String, Any>) : Processor(args) {
+class TappedReader(args: Arguments) : Processor(args) {
   /** The channel which is exposed to the pipeline. */
-  private val input = this.getArgument<Reader>("input")
+  private val input: Reader = arguments["input"]
 
   /** Continuously read data from the input and write it to the global channel. */
   override suspend fun exec() {
diff --git a/src/test/kotlin/processors/TappedWriter.kt b/src/test/kotlin/processors/TappedWriter.kt
index 4d02808..062bf0a 100644
--- a/src/test/kotlin/processors/TappedWriter.kt
+++ b/src/test/kotlin/processors/TappedWriter.kt
@@ -8,15 +8,16 @@ import technology.idlab.parser.intermediate.IRArgument
 import technology.idlab.parser.intermediate.IRParameter
 import technology.idlab.parser.intermediate.IRProcessor
 import technology.idlab.parser.intermediate.IRStage
+import technology.idlab.runner.jvm.Arguments
 
 /**
  * The TappedWriter processor provides a convenient way to write data into the pipeline during
  * testing. All instances listen to a global channel, which can be used directly during testing to
  * write date to.
  */
-class TappedWriter(args: Map<String, Any>) : Processor(args) {
+class TappedWriter(args: Arguments) : Processor(args) {
   /** Writer which is exposed to the pipeline. */
-  private val output = this.getArgument<Writer>("output")
+  private val output: Writer = arguments["output"]
 
   /** Continuously read data from the global channel and write it to the output. */
   override suspend fun exec() {