Feature/init array default values (#296)

* Initialization of arrays

---------

Co-authored-by: phischu <[email protected]>

examples/pos/arrays.check

@@ -2,3 +2,6 @@ Some(hello)
 Some(world)
 None()
 Some(foo)
+Hello World,Hello World,Hello World,Hello World
+0,1,2,3,4
+1,5,17

examples/pos/arrays.effekt

@@ -17,4 +17,13 @@ def main() = {
     println(show(get(arr, 4)));
     put(arr, 4, "foo");
     println(show(get(arr, 4)))
+
+    val arrWithVals = arrayFromValue(4,"Hello World");
+    println(arrWithVals)
+
+    val arrByF = arrayFromLoop(5){ i => i };
+    println(arrByF);
+
+    var arrByList = arrayFromList([1,5,17]);
+    println(arrByList)
 }

libraries/js/immutable/list.effekt

@@ -20,6 +20,17 @@ def foreach[A](l: List[A]) { f: A => Unit } : Unit = {
   }
 }
 
+def foreachIndex[T](list: List[T]){ f: (Int, T) => Unit}: Unit = {
+  def worker[T](list: List[T], i: Int){ f: (Int, T) => Unit}: Unit = {
+    list match {
+      case Nil() => ();
+      case Cons(head, tail) => f(i, head); worker(tail, i+1){f}
+
+    }
+  };
+  worker(list,0){f};
+}
+
 def map[A, B](l: List[A]) { f: A => B } : List[B] = {
   var acc = Nil[B]()
   l.foreach { el => acc = Cons(f(el), acc) }

libraries/js/mutable/array.effekt

@@ -8,6 +8,29 @@ extern type Array[T]
 
 def emptyArray[T](): Array[T] = emptyArray(0)
 
+//initialize array with default values
+def arrayFromValue[T](size: Int, default: T) : Array[T] = {
+  val arr = emptyArray[T](size)
+  each(0,arr.size()){ i=> put(arr, i, default)}
+  return arr;
+}
+
+def arrayFromLoop[T](size: Int) { index: Int => T}: Array[T] = {
+  val arr = emptyArray[T](size)
+  each(0,arr.size()){ i=> put(arr, i, index(i))}
+  return arr
+}
+
+def arrayFromList[T](list: List[T]): Array[T] = {
+  val listSize = list.size();
+  val arr = emptyArray(listSize);
+
+  foreachIndex(list){(i, head) => put(arr, i, head)}
+  return arr;
+}
+
+
+
 extern pure def emptyArray[T](initialSize: Int): Array[T] =
   "(new Array(initialSize))"