splat any Iterable

docs/declaring_arguments.md

@@ -70,7 +70,31 @@ destructuring arrays when calling functions and lambdas:
     fun getFirstAndLast(first, args..., last) {
         [ first, last ]
     }
-    getFirstAndLast( ...(1..10).toList() )
+    getFirstAndLast( ...(1..10) ) // see "splats" section below
     >>> [1, 10]
 
+# Splats
+
+Ellipsis allows to convert argument lists to lists. The inversa algorithm that converts [List],
+or whatever implementing [Iterable], is called _splats_. Here is how we use it:
+
+    fun testSplat(data...) {
+        println(data)
+    }
+    val array = [1,2,3]
+    testSplat("start", ...array, "end")
+    >>> ["start", 1, 2, 3, "end"]
+    >>> void
+
+There could be any number of splats at any positions. You can splat any other [Iterable] type:
+
+    fun testSplat(data...) {
+        println(data)
+    }
+    val range = 1..3
+    testSplat("start", ...range, "end")
+    >>> ["start", 1, 2, 3, "end"]
+    >>> void
+    
+
 [tutorial]: tutorial.md

library/src/commonMain/kotlin/net/sergeych/lyng/Arguments.kt

@@ -8,8 +8,18 @@ suspend fun Collection<ParsedArgument>.toArguments(context: Context): Arguments
     for (x in this) {
         val value = x.value.execute(context)
         if (x.isSplat) {
-            (value as? ObjList) ?: context.raiseClassCastError("expected list of objects for splat argument")
-            for (subitem in value.list) list.add(Arguments.Info(subitem, x.pos))
+            when {
+                value is ObjList -> {
+                    for (subitem in value.list) list.add(Arguments.Info(subitem, x.pos))
+                }
+
+                value.isInstanceOf(ObjIterable) -> {
+                    val i = (value.invokeInstanceMethod(context, "toList") as ObjList).list
+                    i.forEach { list.add(Arguments.Info(it, x.pos)) }
+                }
+
+                else -> context.raiseClassCastError("expected list of objects for splat argument")
+            }
         } else
             list.add(Arguments.Info(value, x.pos))
     }