fancy error printing done

src/main/kotlin/blitz/collections/Bounds.kt

@@ -0,0 +1,17 @@
+package blitz.collections
+
+fun <T> List<T>.inBounds(index: Int): Boolean {
+    if (index >= size)
+        return false
+    if (index < 0)
+        return false
+    return true
+}
+
+fun <T> Vec<T>.inBounds(index: Int): Boolean {
+    if (index >= size)
+        return false
+    if (index < 0)
+        return false
+    return true
+}

src/main/kotlin/blitz/collections/MergeNeighbors.kt

@@ -0,0 +1,22 @@
+package blitz.collections
+
+fun <T, G> Iterable<T>.mergeNeighbors(
+    to: MutableList<Pair<G, MutableList<T>>> = mutableListOf(),
+    by: (T) -> G
+): MutableList<Pair<G, MutableList<T>>> {
+    val out = mutableListOf<Pair<G, MutableList<T>>>()
+    forEach {
+        val b = by(it)
+        if (b == out.lastOrNull()?.first)
+            out.last().second.add(it)
+        else
+            out.add(b to mutableListOf(it))
+    }
+    return out
+}
+
+fun <T, G> Sequence<T>.mergeNeighbors(
+    to: MutableList<Pair<G, MutableList<T>>> = mutableListOf(),
+    by: (T) -> G
+): MutableList<Pair<G, MutableList<T>>> =
+    asIterable().mergeNeighbors(to, by)