diff --git a/examples/skiplist-1-4.p3l b/examples/skiplist-1-4.p3l
deleted file mode 100644
index c60107c..0000000
--- a/examples/skiplist-1-4.p3l
+++ /dev/null
@@ -1,383 +0,0 @@
-// 0: own level (lowest level is 0)
-// 1: entry below this one (exists iff level is greater than 0)
-// 2: entry to the right of this one
-type SkipList<V> = (int, SkipListLink<V>, Option<SkipListNode<V>>);
-
-type SkipListLink<V> = Option<Rc<SkipList<V>>>;
-
-// 0: own level (lowest level is 0)
-// 1: entry below this one (exists iff level is greater than 0)
-// 2: entry to the right of this one
-// 3: key of the column this entry belongs to
-// 4: value of the column (only on the lowest level)
-type SkipListNode<V> = Rc<(int, Option<SkipListNode<V>>, Option<SkipListNode<V>>, int, Option<V>)>;
-
-type Stack<T> = Rc<(Option<(T, Stack<T>)>,)>;
-
-// Unwrap an option.
-fn unwrap<T>(opt: Option<T>) -> T {
-	if let Some(value) = opt {
-		return value;
-	}
-}
-
-// Create a new, empty stack
-fn stack_new<T>() -> Stack<T> {
-	return Rc((None,));
-}
-
-// Push a new value to the stack.
-fn stack_push<T>(stack: Stack<T>, value: T) {
-	stack.0 = Some((value, Rc(*stack)));
-}
-
-// Pop a value from the stack.
-fn stack_pop<T>(stack: Stack<T>) -> Option<T> {
-	if let Some(top) = (*stack).0 {
-		stack.0 = (*top.1).0;
-		return Some(top.0);
-	}
-	return None;
-}
-
-// Return a new, empty skiplist.
-fn skiplist_new<V>() -> SkipList<V> {
-	return (0, None, None);
-}
-
-// Return the current maximum level of the skiplist.
-fn skiplist_level<V>(list: SkipList<V>) -> int {
-	return list.0;
-}
-
-// NOT PUBLIC API
-// Insert a new value into the skiplist at the first position.
-fn skiplist_insert_first<V>(
-	list: SkipList<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	// decompose list into levels
-	let levels: Stack<Option<SkipListNode<V>>> =
-		stack_new::<Option<SkipListNode<V>>>();
-	let _unit: () = stack_push::<Option<SkipListNode<V>>>(levels, list.2);
-	while let Some(next) = list.1 {
-		list = *next;
-		let _unit: () = stack_push::<Option<SkipListNode<V>>>(levels, list.2);
-	}
-	
-	// create new list with just the lowest level
-	let lvl: int = 0;
-	let top: Option<Option<SkipListNode<V>>> = 
-		stack_pop::<Option<SkipListNode<V>>>(levels);
-	let new_node: SkipListNode<V> = Rc((
-		0,
-		None,
-		unwrap::<Option<SkipListNode<V>>>(top),
-		key,
-		Some(value)
-	));
-	list = (0, None, Some(new_node));
-	
-	// rebuild list up to its original level
-	while let Some(top) = stack_pop::<Option<SkipListNode<V>>>(levels) {
-		lvl = lvl + 1;
-		if new_lvl >= lvl {
-			new_node = Rc((lvl, Some(new_node), top, key, None));
-		} else {
-			let top: SkipListNode<V> = unwrap::<SkipListNode<V>>(top);
-			new_node = Rc((lvl, Some(new_node), (*top).2, (*top).3, None));
-		}
-		list = (lvl, Some(Rc(list)), Some(new_node));
-	}
-	
-	// add new levels if necessary
-	while new_lvl > lvl {
-		lvl = lvl + 1;
-		new_node = Rc((lvl, Some(new_node), None, key, None));
-		list = (lvl, Some(Rc(list)), Some(new_node));
-	}
-	
-	return list;
-}
-
-// NOT PUBLIC API
-// Insert a new value into the skiplist that needs to be inserted after
-// the current node. Will be called when entering a new level while
-// searching for the insert position. Returns the level of the inserted
-// node.
-fn skiplist_insert_impl<V>(
-	node: SkipListNode<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> Option<SkipListNode<V>> {
-	// go to the last node in the level whose key is less than the new key
-	while true {
-		if let Some(next) = (*node).2 {
-			if (*next).3 < key {
-				node = next;
-				continue;
-			}
-		}
-		break;
-	}
-	
-	// when not at the lowest level, descend
-	if let Some(below) = (*node).1 {
-		let new_node: Option<SkipListNode<V>> =
-			skiplist_insert_impl::<V>(below, new_lvl, key, value);
-		if let Some(new_node) = new_node {
-			let node_lvl: int = (*node).0;
-			if new_lvl >= node_lvl {
-				let new_node: SkipListNode<V> =
-					Rc((node_lvl, Some(new_node), (*node).2, key, None));
-				node.2 = Some(new_node);
-				return Some(new_node);
-			}
-		}
-		return new_node;
-	}
-	
-	// if we found a node with the exact key, just update the value
-	if (*node).3 == key {
-		node.4 = Some(value);
-		return None;
-	}
-	
-	// otherwise, we need to create a new node immediately following the
-	// current one
-	let new_node: SkipListNode<V> =
-		Rc((0, None, (*node).2, key, Some(value)));
-	node.2 = Some(new_node);
-	return Some(new_node);
-}
-
-// NOT PUBLIC API
-// Insert a new value with a set level.
-fn skiplist_insert_with_level<V>(
-	orig_list: SkipList<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	// find the level at which to start search for the insert position
-	let list: SkipList<V> = orig_list;
-	while true {
-		if let Some(level) = list.2 {
-			if (*level).3 <= key {
-				break;
-			}
-		}
-		
-		if let Some(below) = list.1 {
-			list = *below;
-		} else {
-			return skiplist_insert_first::<V>(list, new_lvl, key, value);
-		}
-	}
-	
-	if let Some(node) = list.2 {
-		let new_node: Option<SkipListNode<V>> =
-			skiplist_insert_impl::<V>(node, new_lvl, key, value);
-		if let Some(new_node) = new_node {
-			let node_lvl: int = (*node).0;
-			
-			// update levels above node_lvl if necessary
-			list = orig_list;
-			if new_lvl >= list.0 {
-				let new_node: SkipListNode<V> =
-					Rc((list.0, None, list.2, key, None));
-				list.2 = Some(new_node);
-			}
-			while let Some(below) = list.1 {
-				list = *below;
-				if list.0 <= node_lvl || list.0 < new_lvl {
-					break;
-				}
-				let new_node: SkipListNode<V> =
-					Rc((list.0, None, list.2, key, None));
-				list.2 = Some(new_node);
-			}
-			
-			// add levels above the list level if necessary
-			list = orig_list;
-			while new_lvl > list.0 {
-				new_node = Rc((list.0, Some(new_node), None, key, None));
-				list = (list.0 + 1, Some(Rc(list)), Some(new_node));
-			}
-			
-			return list;
-		} else {
-			return orig_list;
-		}
-	} else {
-		// we are inserting into an empty list
-		return skiplist_insert_first::<V>(list, new_lvl, key, value);
-	}
-}
-
-// NOT PUBLIC API
-// Return a random level.
-fn skiplist_random_level() -> int {
-	let lvl: int = 0;
-	while true {
-		{ lvl = lvl + 1; } [0.25] { return lvl; }
-	}
-}
-
-// Take the skiplist, insert a new value, and return the skiplist.
-fn skiplist_insert<V>(
-	list: SkipList<V>,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	let lvl: int = skiplist_random_level();
-	return skiplist_insert_with_level::<V>(list, lvl, key, value);
-}
-
-// NOT PUBLIC API
-// Find a value in the skiplist, starting the search at a specific node.
-// Return the value along with the path length of the search.
-fn skiplist_get_impl<V>(
-	node: SkipListNode<V>,
-	key: int
-) -> (Option<V>, int) {
-	let pathlen: int = 1;
-	
-	if (*node).3 < key {
-		while true {
-			if let Some(next) = (*node).2 {
-				let next_key: int = (*next).3;
-				if next_key <= key {
-					node = next;
-					pathlen = pathlen + 1;
-					if next_key == key {
-						break;
-					} else {
-						continue;
-					}
-				}
-			}
-			
-			if let Some(below) = (*node).1 {
-				node = below;
-				continue;
-			}
-			
-			break;
-		}
-	}
-	
-	if (*node).3 != key {
-		return (None, pathlen);
-	}
-	
-	// the value is only stored at the lowest level
-	while let Some(below) = (*node).1 {
-		node = below;
-	}
-	return (Some(unwrap::<V>((*node).4)), pathlen);
-}
-
-// Find a value in the skiplist. Return the value along with the path
-// length of the search.
-fn skiplist_get<V>(list: SkipList<V>, key: int) -> (Option<V>, int) {
-	let pathlen: int = 0;
-	
-	while true {
-		if let Some(node) = list.2 {
-			if (*node).3 <= key {
-				let tmp: (Option<V>, int) = skiplist_get_impl::<V>(node, key);
-				return (tmp.0, pathlen + tmp.1);
-			}
-		}
-		
-		if let Some(below) = list.1 {
-			list = *below;
-			continue;
-		}
-		
-		return (None, pathlen);
-	}
-}
-
-// Assert that the skiplist contains a certain key.
-fn assert_contains<V>(list: SkipList<V>, key: int) -> () {
-	if let Some(_value) = skiplist_get::<V>(list, key).0 {
-		return ();
-	}
-}
-
-// Return the length of the skiplist.
-fn skiplist_len<V>(list: SkipList<V>) -> int {
-	// descend to the lowest level
-	while let Some(next) = list.1 {
-		list = *next;
-	}
-	
-	// count the lowest level
-	let node: Option<SkipListNode<V>> = list.2;
-	let len: int = 0;
-	while let Some(next) = node {
-		len = len + 1;
-		node = (*next).2;
-	}
-	return len;
-}
-
-// Assert that the skiplist has the correct length.
-fn assert_len<V>(list: SkipList<V>, len: int) -> () {
-	if skiplist_len::<V>(list) == len {
-		return ();
-	}
-}
-
-// Assert that a value is in a certain range.
-fn assert_in_range(value: int, min_incl: int, max_excl: int) -> () {
-	if value >= min_incl && value < max_excl {
-		return ();
-	}
-}
-
-// Return a random number between 0 (inclusive) and
-// max (exclusive).
-fn random(max: int) -> int {
-	while true {
-		let value: int = 0;
-		let max_value: int = 0;
-		while max_value < max {
-			max_value = max_value * 2 + 1;
-			value = value * 2;
-			{ value = value + 1; } [0.25] {}
-		}
-		if value < max {
-			return value;
-		}
-	}
-}
-
-input!(len);
-
-// create a new list with entries 0..len
-let list: SkipList<()> = skiplist_new::<()>();
-let i: int = 0;
-while i < len {
-	list = skiplist_insert::<()>(list, i, ());
-	let _unit: () = assert_contains::<()>(list, i);
-	i = i + 1;
-}
-let _unit: () = assert_len::<()>(list, len);
-
-// lookup a random value in the list
-let key: int = random(len);
-let _unit: () = assert_in_range(key, 0, len);
-let lookup: (Option<()>, int) = skiplist_get::<()>(list, key);
-let _unit: () = unwrap::<()>(lookup.0);
-
-let pathlen: int = lookup.1;
-let lvl: int = skiplist_level::<()>(list);
-
-output!(len);
-output!(lvl, pathlen);
diff --git a/examples/skiplist-3-8.p3l b/examples/skiplist-3-8.p3l
deleted file mode 100644
index 356d95d..0000000
--- a/examples/skiplist-3-8.p3l
+++ /dev/null
@@ -1,383 +0,0 @@
-// 0: own level (lowest level is 0)
-// 1: entry below this one (exists iff level is greater than 0)
-// 2: entry to the right of this one
-type SkipList<V> = (int, SkipListLink<V>, Option<SkipListNode<V>>);
-
-type SkipListLink<V> = Option<Rc<SkipList<V>>>;
-
-// 0: own level (lowest level is 0)
-// 1: entry below this one (exists iff level is greater than 0)
-// 2: entry to the right of this one
-// 3: key of the column this entry belongs to
-// 4: value of the column (only on the lowest level)
-type SkipListNode<V> = Rc<(int, Option<SkipListNode<V>>, Option<SkipListNode<V>>, int, Option<V>)>;
-
-type Stack<T> = Rc<(Option<(T, Stack<T>)>,)>;
-
-// Unwrap an option.
-fn unwrap<T>(opt: Option<T>) -> T {
-	if let Some(value) = opt {
-		return value;
-	}
-}
-
-// Create a new, empty stack
-fn stack_new<T>() -> Stack<T> {
-	return Rc((None,));
-}
-
-// Push a new value to the stack.
-fn stack_push<T>(stack: Stack<T>, value: T) {
-	stack.0 = Some((value, Rc(*stack)));
-}
-
-// Pop a value from the stack.
-fn stack_pop<T>(stack: Stack<T>) -> Option<T> {
-	if let Some(top) = (*stack).0 {
-		stack.0 = (*top.1).0;
-		return Some(top.0);
-	}
-	return None;
-}
-
-// Return a new, empty skiplist.
-fn skiplist_new<V>() -> SkipList<V> {
-	return (0, None, None);
-}
-
-// Return the current maximum level of the skiplist.
-fn skiplist_level<V>(list: SkipList<V>) -> int {
-	return list.0;
-}
-
-// NOT PUBLIC API
-// Insert a new value into the skiplist at the first position.
-fn skiplist_insert_first<V>(
-	list: SkipList<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	// decompose list into levels
-	let levels: Stack<Option<SkipListNode<V>>> =
-		stack_new::<Option<SkipListNode<V>>>();
-	let _unit: () = stack_push::<Option<SkipListNode<V>>>(levels, list.2);
-	while let Some(next) = list.1 {
-		list = *next;
-		let _unit: () = stack_push::<Option<SkipListNode<V>>>(levels, list.2);
-	}
-	
-	// create new list with just the lowest level
-	let lvl: int = 0;
-	let top: Option<Option<SkipListNode<V>>> = 
-		stack_pop::<Option<SkipListNode<V>>>(levels);
-	let new_node: SkipListNode<V> = Rc((
-		0,
-		None,
-		unwrap::<Option<SkipListNode<V>>>(top),
-		key,
-		Some(value)
-	));
-	list = (0, None, Some(new_node));
-	
-	// rebuild list up to its original level
-	while let Some(top) = stack_pop::<Option<SkipListNode<V>>>(levels) {
-		lvl = lvl + 1;
-		if new_lvl >= lvl {
-			new_node = Rc((lvl, Some(new_node), top, key, None));
-		} else {
-			let top: SkipListNode<V> = unwrap::<SkipListNode<V>>(top);
-			new_node = Rc((lvl, Some(new_node), (*top).2, (*top).3, None));
-		}
-		list = (lvl, Some(Rc(list)), Some(new_node));
-	}
-	
-	// add new levels if necessary
-	while new_lvl > lvl {
-		lvl = lvl + 1;
-		new_node = Rc((lvl, Some(new_node), None, key, None));
-		list = (lvl, Some(Rc(list)), Some(new_node));
-	}
-	
-	return list;
-}
-
-// NOT PUBLIC API
-// Insert a new value into the skiplist that needs to be inserted after
-// the current node. Will be called when entering a new level while
-// searching for the insert position. Returns the level of the inserted
-// node.
-fn skiplist_insert_impl<V>(
-	node: SkipListNode<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> Option<SkipListNode<V>> {
-	// go to the last node in the level whose key is less than the new key
-	while true {
-		if let Some(next) = (*node).2 {
-			if (*next).3 < key {
-				node = next;
-				continue;
-			}
-		}
-		break;
-	}
-	
-	// when not at the lowest level, descend
-	if let Some(below) = (*node).1 {
-		let new_node: Option<SkipListNode<V>> =
-			skiplist_insert_impl::<V>(below, new_lvl, key, value);
-		if let Some(new_node) = new_node {
-			let node_lvl: int = (*node).0;
-			if new_lvl >= node_lvl {
-				let new_node: SkipListNode<V> =
-					Rc((node_lvl, Some(new_node), (*node).2, key, None));
-				node.2 = Some(new_node);
-				return Some(new_node);
-			}
-		}
-		return new_node;
-	}
-	
-	// if we found a node with the exact key, just update the value
-	if (*node).3 == key {
-		node.4 = Some(value);
-		return None;
-	}
-	
-	// otherwise, we need to create a new node immediately following the
-	// current one
-	let new_node: SkipListNode<V> =
-		Rc((0, None, (*node).2, key, Some(value)));
-	node.2 = Some(new_node);
-	return Some(new_node);
-}
-
-// NOT PUBLIC API
-// Insert a new value with a set level.
-fn skiplist_insert_with_level<V>(
-	orig_list: SkipList<V>,
-	new_lvl: int,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	// find the level at which to start search for the insert position
-	let list: SkipList<V> = orig_list;
-	while true {
-		if let Some(level) = list.2 {
-			if (*level).3 <= key {
-				break;
-			}
-		}
-		
-		if let Some(below) = list.1 {
-			list = *below;
-		} else {
-			return skiplist_insert_first::<V>(list, new_lvl, key, value);
-		}
-	}
-	
-	if let Some(node) = list.2 {
-		let new_node: Option<SkipListNode<V>> =
-			skiplist_insert_impl::<V>(node, new_lvl, key, value);
-		if let Some(new_node) = new_node {
-			let node_lvl: int = (*node).0;
-			
-			// update levels above node_lvl if necessary
-			list = orig_list;
-			if new_lvl >= list.0 {
-				let new_node: SkipListNode<V> =
-					Rc((list.0, None, list.2, key, None));
-				list.2 = Some(new_node);
-			}
-			while let Some(below) = list.1 {
-				list = *below;
-				if list.0 <= node_lvl || list.0 < new_lvl {
-					break;
-				}
-				let new_node: SkipListNode<V> =
-					Rc((list.0, None, list.2, key, None));
-				list.2 = Some(new_node);
-			}
-			
-			// add levels above the list level if necessary
-			list = orig_list;
-			while new_lvl > list.0 {
-				new_node = Rc((list.0, Some(new_node), None, key, None));
-				list = (list.0 + 1, Some(Rc(list)), Some(new_node));
-			}
-			
-			return list;
-		} else {
-			return orig_list;
-		}
-	} else {
-		// we are inserting into an empty list
-		return skiplist_insert_first::<V>(list, new_lvl, key, value);
-	}
-}
-
-// NOT PUBLIC API
-// Return a random level.
-fn skiplist_random_level() -> int {
-	let lvl: int = 0;
-	while true {
-		{ lvl = lvl + 1; } [0.375] { return lvl; }
-	}
-}
-
-// Take the skiplist, insert a new value, and return the skiplist.
-fn skiplist_insert<V>(
-	list: SkipList<V>,
-	key: int,
-	value: V
-) -> SkipList<V> {
-	let lvl: int = skiplist_random_level();
-	return skiplist_insert_with_level::<V>(list, lvl, key, value);
-}
-
-// NOT PUBLIC API
-// Find a value in the skiplist, starting the search at a specific node.
-// Return the value along with the path length of the search.
-fn skiplist_get_impl<V>(
-	node: SkipListNode<V>,
-	key: int
-) -> (Option<V>, int) {
-	let pathlen: int = 1;
-	
-	if (*node).3 < key {
-		while true {
-			if let Some(next) = (*node).2 {
-				let next_key: int = (*next).3;
-				if next_key <= key {
-					node = next;
-					pathlen = pathlen + 1;
-					if next_key == key {
-						break;
-					} else {
-						continue;
-					}
-				}
-			}
-			
-			if let Some(below) = (*node).1 {
-				node = below;
-				continue;
-			}
-			
-			break;
-		}
-	}
-	
-	if (*node).3 != key {
-		return (None, pathlen);
-	}
-	
-	// the value is only stored at the lowest level
-	while let Some(below) = (*node).1 {
-		node = below;
-	}
-	return (Some(unwrap::<V>((*node).4)), pathlen);
-}
-
-// Find a value in the skiplist. Return the value along with the path
-// length of the search.
-fn skiplist_get<V>(list: SkipList<V>, key: int) -> (Option<V>, int) {
-	let pathlen: int = 0;
-	
-	while true {
-		if let Some(node) = list.2 {
-			if (*node).3 <= key {
-				let tmp: (Option<V>, int) = skiplist_get_impl::<V>(node, key);
-				return (tmp.0, pathlen + tmp.1);
-			}
-		}
-		
-		if let Some(below) = list.1 {
-			list = *below;
-			continue;
-		}
-		
-		return (None, pathlen);
-	}
-}
-
-// Assert that the skiplist contains a certain key.
-fn assert_contains<V>(list: SkipList<V>, key: int) -> () {
-	if let Some(_value) = skiplist_get::<V>(list, key).0 {
-		return ();
-	}
-}
-
-// Return the length of the skiplist.
-fn skiplist_len<V>(list: SkipList<V>) -> int {
-	// descend to the lowest level
-	while let Some(next) = list.1 {
-		list = *next;
-	}
-	
-	// count the lowest level
-	let node: Option<SkipListNode<V>> = list.2;
-	let len: int = 0;
-	while let Some(next) = node {
-		len = len + 1;
-		node = (*next).2;
-	}
-	return len;
-}
-
-// Assert that the skiplist has the correct length.
-fn assert_len<V>(list: SkipList<V>, len: int) -> () {
-	if skiplist_len::<V>(list) == len {
-		return ();
-	}
-}
-
-// Assert that a value is in a certain range.
-fn assert_in_range(value: int, min_incl: int, max_excl: int) -> () {
-	if value >= min_incl && value < max_excl {
-		return ();
-	}
-}
-
-// Return a random number between 0 (inclusive) and
-// max (exclusive).
-fn random(max: int) -> int {
-	while true {
-		let value: int = 0;
-		let max_value: int = 0;
-		while max_value < max {
-			max_value = max_value * 2 + 1;
-			value = value * 2;
-			{ value = value + 1; } [0.375] {}
-		}
-		if value < max {
-			return value;
-		}
-	}
-}
-
-input!(len);
-
-// create a new list with entries 0..len
-let list: SkipList<()> = skiplist_new::<()>();
-let i: int = 0;
-while i < len {
-	list = skiplist_insert::<()>(list, i, ());
-	let _unit: () = assert_contains::<()>(list, i);
-	i = i + 1;
-}
-let _unit: () = assert_len::<()>(list, len);
-
-// lookup a random value in the list
-let key: int = random(len);
-let _unit: () = assert_in_range(key, 0, len);
-let lookup: (Option<()>, int) = skiplist_get::<()>(list, key);
-let _unit: () = unwrap::<()>(lookup.0);
-
-let pathlen: int = lookup.1;
-let lvl: int = skiplist_level::<()>(list);
-
-output!(len);
-output!(lvl, pathlen);