diff --git a/website/src/playground/files/root/examples/useRange.ts b/website/src/playground/files/root/examples/useRange.ts
new file mode 100644
index 00000000..57c40bdf
--- /dev/null
+++ b/website/src/playground/files/root/examples/useRange.ts
@@ -0,0 +1,23 @@
+// This program solves https://projecteuler.net/problem=2 using the `Range`
+// library. Range provides operations on iterables that are very similar to the
+// higher order functions on arrays. By using iterables, you can work with
+// infinite sequences (eg fibonacci), and the processing is done incrementally
+// instead of serializing each step into memory.
+
+import { Range } from "../lib/mod.ts";
+
+export default function main() {
+  return Range.from(fibonacci())
+    .while((x) => x < 4_000_000)
+    .filter((x) => x % 2 === 0)
+    .sum();
+}
+
+function* fibonacci() {
+  let [fibLast, fib] = [0, 1];
+
+  while (true) {
+    yield fib;
+    [fibLast, fib] = [fib, fibLast + fib];
+  }
+}
diff --git a/website/src/playground/files/root/lib/Range.ts b/website/src/playground/files/root/lib/Range.ts
new file mode 100644
index 00000000..7f09b712
--- /dev/null
+++ b/website/src/playground/files/root/lib/Range.ts
@@ -0,0 +1,423 @@
+import { primes } from "./primes.ts";
+
+export default class Range<T = never> implements Iterable<T> {
+  iterable: Iterable<T>;
+
+  constructor(iterable: Iterable<T>) {
+    this.iterable = iterable;
+  }
+
+  [Symbol.iterator]() {
+    return this.iterable[Symbol.iterator]();
+  }
+
+  limit(n: number) {
+    const iterable = this.iterable;
+
+    function* res() {
+      let i = 0;
+
+      for (const x of iterable) {
+        if (i >= n) {
+          break;
+        }
+
+        yield x;
+        i++;
+      }
+    }
+
+    return new Range(res());
+  }
+
+  count() {
+    let i = 0;
+
+    for (const _x of this.iterable) {
+      i++;
+    }
+
+    return i;
+  }
+
+  empty() {
+    for (const _x of this.iterable) {
+      return false;
+    }
+
+    return true;
+  }
+
+  stringJoin(sep = "") {
+    let iter = this[Symbol.iterator]();
+
+    const first = iter.next();
+
+    if (first.done) {
+      return "";
+    }
+
+    let res = String(first.value);
+
+    for (const x of asIterable(iter)) {
+      res += sep;
+      res += x;
+    }
+
+    return res;
+  }
+
+  sum(
+    // Warning: ValueScript has a bug where typing the `this` parameter causes it to create a
+    // phantom regular parameter. This only works because there aren't any other parameters.
+    // TODO: Fix this.
+    this: Range<number>,
+  ) {
+    let res = 0;
+
+    for (const x of this.iterable) {
+      res += x;
+    }
+
+    return res;
+  }
+
+  bigSum(
+    // Warning: ValueScript has a bug where typing the `this` parameter causes it to create a
+    // phantom regular parameter. This only works because there aren't any other parameters.
+    // TODO: Fix this.
+    this: Range<bigint>,
+  ) {
+    let res = 0n;
+
+    for (const x of this.iterable) {
+      res += x;
+    }
+
+    return res;
+  }
+
+  product(this: Range<number>) {
+    let res = 1;
+
+    for (const x of this.iterable) {
+      res *= x;
+    }
+
+    return res;
+  }
+
+  bigProduct(
+    // Warning: ValueScript has a bug where typing the `this` parameter causes it to create a
+    // phantom regular parameter. This only works because there aren't any other parameters.
+    // TODO: Fix this.
+    this: Range<bigint>,
+  ) {
+    let res = 1n;
+
+    for (const x of this.iterable) {
+      res *= x;
+    }
+
+    return res;
+  }
+
+  map<MappedT>(fn: (x: T) => MappedT) {
+    const iterable = this.iterable;
+
+    function* res() {
+      for (const x of iterable) {
+        yield fn(x);
+      }
+    }
+
+    return new Range(res());
+  }
+
+  flatMap<MappedT>(fn: (x: T) => Iterable<MappedT>) {
+    const iterable = this.iterable;
+
+    function* res() {
+      for (const x of iterable) {
+        for (const y of fn(x)) {
+          yield y;
+        }
+      }
+    }
+
+    return new Range(res());
+  }
+
+  flatten<U>(this: Range<Iterable<U>>) {
+    const iterable = this.iterable;
+
+    function* res() {
+      for (const x of iterable) {
+        for (const y of x) {
+          yield y;
+        }
+      }
+    }
+
+    return new Range(res());
+  }
+
+  filter(fn: (x: T) => boolean) {
+    const iterable = this.iterable;
+
+    function* res() {
+      for (const x of iterable) {
+        if (fn(x)) {
+          yield x;
+        }
+      }
+    }
+
+    return new Range(res());
+  }
+
+  // TODO: Negative indexes
+  at(n: number) {
+    let i = 0;
+
+    for (const x of this.iterable) {
+      if (i === n) {
+        return x;
+      }
+
+      i++;
+    }
+  }
+
+  first() {
+    for (const x of this.iterable) {
+      return x;
+    }
+  }
+
+  last() {
+    let res: T | undefined;
+
+    for (const x of this.iterable) {
+      res = x;
+    }
+
+    return res;
+  }
+
+  indexed() {
+    const iterable = this.iterable;
+
+    function* res() {
+      let i = 0;
+
+      for (const x of iterable) {
+        yield [i, x] as [number, T];
+        i++;
+      }
+    }
+
+    return new Range(res());
+  }
+
+  append<U>(newItems: Iterable<U>) {
+    const iterable = this.iterable;
+
+    function* res() {
+      yield* iterable;
+      yield* newItems;
+    }
+
+    return new Range(res());
+  }
+
+  prepend<U>(newItems: Iterable<U>) {
+    const iterable = this.iterable;
+
+    function* res() {
+      yield* newItems;
+      yield* iterable;
+    }
+
+    return new Range(res());
+  }
+
+  zip<U>(other: Iterable<U>) {
+    const iterable = this.iterable;
+
+    function* res() {
+      let iter1 = iterable[Symbol.iterator]();
+      let iter2 = other[Symbol.iterator]();
+
+      while (true) {
+        const x1 = iter1.next();
+        const x2 = iter2.next();
+
+        if (x1.done || x2.done) {
+          break;
+        }
+
+        yield [x1.value, x2.value] as [T, U];
+      }
+    }
+
+    return new Range(res());
+  }
+
+  skip(n: number) {
+    const iterable = this.iterable;
+
+    function* res() {
+      let iter = iterable[Symbol.iterator]();
+
+      for (let i = 0; i < n; i++) {
+        iter.next();
+      }
+
+      while (true) {
+        const x = iter.next();
+
+        if (x.done) {
+          break;
+        }
+
+        yield x.value;
+      }
+    }
+
+    return new Range(res());
+  }
+
+  reduce<S>(state: S, fn: (state: S, x: T) => S) {
+    for (const x of this.iterable) {
+      state = fn(state, x);
+    }
+
+    return state;
+  }
+
+  while(fn: (x: T) => boolean) {
+    const iterable = this.iterable;
+
+    function* res() {
+      for (const x of iterable) {
+        if (fn(x)) {
+          yield x;
+        } else {
+          break;
+        }
+      }
+    }
+
+    return new Range(res());
+  }
+
+  window(len: number) {
+    const iterable = this.iterable;
+
+    function* res() {
+      let iter = iterable[Symbol.iterator]();
+      let memory = [];
+
+      for (let i = 0; i < len; i++) {
+        const { value, done } = iter.next();
+
+        if (done) {
+          return;
+        }
+
+        memory.push(value);
+      }
+
+      yield new Range(memory);
+
+      let i = 0;
+
+      for (const x of asIterable(iter)) {
+        memory[i] = x;
+
+        const memoryCopy = memory;
+        const iCopy = i;
+
+        yield new Range((function* () {
+          for (let j = 1; j <= len; j++) {
+            yield memoryCopy[(iCopy + j) % len];
+          }
+        })());
+
+        i++;
+        i %= len;
+      }
+    }
+
+    return new Range(res());
+  }
+
+  static fromConversion<T = never>(
+    iter?: Iterable<T> | Iterator<T> | (() => Iterable<T>),
+  ) {
+    if (iter === undefined) {
+      return new Range([]);
+    }
+
+    if (typeof iter === "function") {
+      return new Range(iter());
+    }
+
+    // TODO: `in` operator
+    if (hasKey(iter, Symbol.iterator)) {
+      return new Range(iter);
+    }
+
+    if (hasKey(iter, "next")) {
+      return Range.fromIterator(iter);
+    }
+
+    never(iter);
+  }
+
+  static from<T = never>(iterable: Iterable<T> = []) {
+    return new Range<T>(iterable);
+  }
+
+  static fromIterator<T = never>(iterator: Iterator<T>) {
+    return new Range<T>({
+      [Symbol.iterator]: () => iterator,
+    });
+  }
+
+  static numbers(start = 0, end?: number) {
+    if (end === undefined) {
+      return new Range((function* () {
+        for (let i = start;; i++) {
+          yield i;
+        }
+      })());
+    }
+
+    return new Range((function* () {
+      for (let i = start; i < end; i++) {
+        yield i;
+      }
+    })());
+  }
+
+  static primes() {
+    return new Range(primes());
+  }
+}
+
+function hasKey<Obj, K extends string | symbol>(
+  obj: unknown,
+  key: K,
+): obj is Obj & Record<K, unknown> {
+  return (obj as Record<K, unknown>)[key] !== undefined;
+}
+
+function never(x: never): never {
+  throw new Error(`Unexpected value: ${x}`);
+}
+
+function asIterable<T>(iterator: Iterator<T>): Iterable<T> {
+  return { [Symbol.iterator]: () => iterator };
+}
diff --git a/website/src/playground/files/root/lib/mod.ts b/website/src/playground/files/root/lib/mod.ts
index 6c6af63f..bea25da6 100644
--- a/website/src/playground/files/root/lib/mod.ts
+++ b/website/src/playground/files/root/lib/mod.ts
@@ -1,6 +1,6 @@
 export { default as BinaryTree } from "./BinaryTree.ts";
 export { type NotNullish } from "./util.ts";
-export { factorize, factorizeAsPowers, primes, isPrime } from "./primes.ts";
-export { default as range } from "./range.ts";
+export { factorize, factorizeAsPowers, isPrime, primes } from "./primes.ts";
+export { default as Range } from "./Range.ts";
 
 // Note: `export *` would be used here, but it isn't implemented yet.
diff --git a/website/src/playground/files/root/lib/range.ts b/website/src/playground/files/root/lib/range.ts
deleted file mode 100644
index 9b6e065f..00000000
--- a/website/src/playground/files/root/lib/range.ts
+++ /dev/null
@@ -1,312 +0,0 @@
-import { primes } from "./primes.ts";
-
-export default function range<T>(iterable: Iterable<T>) {
-  return new Range(iterable);
-}
-
-// TODO: Static methods
-export function Range_from<T = never>(
-  iter?: Iterable<T> | Iterator<T> | (() => Iterable<T>),
-) {
-  if (iter === undefined) {
-    return Range_fromIterable([]);
-  }
-
-  if (typeof iter === "function") {
-    return Range_fromIterable(iter());
-  }
-
-  // TODO: `in` operator
-  if (hasKey(iter, Symbol.iterator)) {
-    return Range_fromIterable(iter);
-  }
-
-  if (hasKey(iter, "next")) {
-    return Range_fromIterator(iter);
-  }
-
-  never(iter);
-}
-
-export function Range_fromIterable<T = never>(iterable: Iterable<T> = []) {
-  return new Range<T>(iterable);
-}
-
-export function Range_fromIterator<T = never>(iterator: Iterator<T>) {
-  return new Range<T>({
-    [Symbol.iterator]: () => iterator,
-  });
-}
-
-export function Range_numbers(start: number, end: number) {
-  function* res() {
-    for (let i = start; i < end; i++) {
-      yield i;
-    }
-  }
-
-  return Range_fromIterable(res());
-}
-
-export function Range_primes() {
-  return new Range(primes());
-}
-
-export class Range<T = never> implements Iterable<T> {
-  iterable: Iterable<T>;
-
-  constructor(iterable: Iterable<T>) {
-    this.iterable = iterable;
-  }
-
-  [Symbol.iterator]() {
-    return this.iterable[Symbol.iterator]();
-  }
-
-  limit(n: number) {
-    const iterable = this.iterable;
-
-    function* res() {
-      let i = 0;
-
-      for (const x of iterable) {
-        if (i >= n) {
-          break;
-        }
-
-        yield x;
-        i++;
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  count() {
-    let i = 0;
-
-    for (const _x of this.iterable) {
-      i++;
-    }
-
-    return i;
-  }
-
-  empty() {
-    for (const _x of this.iterable) {
-      return false;
-    }
-
-    return true;
-  }
-
-  stringJoin(sep = "") {
-    let iter = this[Symbol.iterator]();
-
-    const first = iter.next();
-
-    if (first.done) {
-      return "";
-    }
-
-    let res = String(first.value);
-
-    for (const x of this.iterable) {
-      res += sep;
-      res += x;
-    }
-
-    return res;
-  }
-
-  sum(): T extends number ? number : never {
-    let res = 0;
-
-    for (const x of this.iterable) {
-      res += x as number;
-    }
-
-    return res as T extends number ? number : never;
-  }
-
-  product(): T extends number ? number : never {
-    let res = 1;
-
-    for (const x of this.iterable) {
-      res *= x as number;
-    }
-
-    return res as T extends number ? number : never;
-  }
-
-  map<MappedT>(fn: (x: T) => MappedT) {
-    const iterable = this.iterable;
-
-    function* res() {
-      for (const x of iterable) {
-        yield fn(x);
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  flatMap<MappedT>(fn: (x: T) => Iterable<MappedT>) {
-    const iterable = this.iterable;
-
-    function* res() {
-      for (const x of iterable) {
-        for (const y of fn(x)) {
-          yield y;
-        }
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  filter(fn: (x: T) => boolean) {
-    const iterable = this.iterable;
-
-    function* res() {
-      for (const x of iterable) {
-        if (fn(x)) {
-          yield x;
-        }
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  // TODO: Negative indexes
-  at(n: number) {
-    let i = 0;
-
-    for (const x of this.iterable) {
-      if (i === n) {
-        return x;
-      }
-
-      i++;
-    }
-  }
-
-  first() {
-    for (const x of this.iterable) {
-      return x;
-    }
-  }
-
-  last() {
-    let res: T | undefined;
-
-    for (const x of this.iterable) {
-      res = x;
-    }
-
-    return res;
-  }
-
-  indexed() {
-    const iterable = this.iterable;
-
-    function* res() {
-      let i = 0;
-
-      for (const x of iterable) {
-        yield [i, x] as [number, T];
-        i++;
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  append<U>(newItems: Iterable<U>) {
-    const iterable = this.iterable;
-
-    function* res() {
-      yield* iterable;
-      yield* newItems;
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  prepend<U>(newItems: Iterable<U>) {
-    const iterable = this.iterable;
-
-    function* res() {
-      yield* newItems;
-      yield* iterable;
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  zip<U>(other: Iterable<U>) {
-    const iterable = this.iterable;
-
-    function* res() {
-      let iter1 = iterable[Symbol.iterator]();
-      let iter2 = other[Symbol.iterator]();
-
-      while (true) {
-        const x1 = iter1.next();
-        const x2 = iter2.next();
-
-        if (x1.done || x2.done) {
-          break;
-        }
-
-        yield [x1.value, x2.value] as [T, U];
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  skip(n: number) {
-    const iterable = this.iterable;
-
-    function* res() {
-      let iter = iterable[Symbol.iterator]();
-
-      for (let i = 0; i < n; i++) {
-        iter.next();
-      }
-
-      while (true) {
-        const x = iter.next();
-
-        if (x.done) {
-          break;
-        }
-
-        yield x.value;
-      }
-    }
-
-    return Range_fromIterable(res());
-  }
-
-  reduce<S>(state: S, fn: (state: S, x: T) => S) {
-    for (const x of this.iterable) {
-      state = fn(state, x);
-    }
-
-    return state;
-  }
-}
-
-function hasKey<Obj, K extends string | symbol>(
-  obj: unknown,
-  key: K,
-): obj is Obj & Record<K, unknown> {
-  return (obj as Record<K, unknown>)[key] !== undefined;
-}
-
-function never(x: never): never {
-  throw new Error(`Unexpected value: ${x}`);
-}