Rename package root

The package root is now bjc, not io.github.bculkin2442.

6 files changed, 802 insertions, 0 deletions

diff --git a/src/main/java/bjc/data/internals/BoundLazy.java b/src/main/java/bjc/data/internals/BoundLazy.java
new file mode 100644
index 0000000..728af8e
--- /dev/null
+++ b/src/main/java/bjc/data/internals/BoundLazy.java
@@ -0,0 +1,137 @@
+package bjc.data.internals;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.function.UnaryOperator;
+
+import bjc.data.IHolder;
+import bjc.data.Lazy;
+import bjc.funcdata.FunctionalList;
+import bjc.funcdata.IList;
+
+/**
+ * Implements a lazy holder that has been bound.
+ *
+ * @author Ben Culkin
+ */
+@SuppressWarnings("javadoc")
+public class BoundLazy<OldType, BoundContainedType> implements IHolder<BoundContainedType> {
+	/* The old value. */
+	private final Supplier<IHolder<OldType>> oldSupplier;
+
+	/* The function to use to transform the old value into a new value. */
+	private final Function<OldType, IHolder<BoundContainedType>> binder;
+
+	/* The bound value being held. */
+	private IHolder<BoundContainedType> boundHolder;
+
+	/* Whether the bound value has been actualized or not. */
+	private boolean holderBound;
+
+	/* Transformations currently pending on the bound value. */
+	private final IList<UnaryOperator<BoundContainedType>> actions = new FunctionalList<>();
+
+	/**
+	 * Create a new bound lazy value.
+	 *
+	 * @param supp
+	 *        The supplier of the old value.
+	 *
+	 * @param binder
+	 *        The function to use to bind the old value to the new one.
+	 */
+	public BoundLazy(final Supplier<IHolder<OldType>> supp,
+			final Function<OldType, IHolder<BoundContainedType>> binder) {
+		oldSupplier = supp;
+		this.binder = binder;
+	}
+
+	@Override
+	public <BoundType> IHolder<BoundType> bind(final Function<BoundContainedType, IHolder<BoundType>> bindr) {
+		if(bindr == null) throw new NullPointerException("Binder must not be null");
+
+		/* Prepare a list of pending actions. */
+		final IList<UnaryOperator<BoundContainedType>> pendingActions = new FunctionalList<>();
+		actions.forEach(pendingActions::add);
+
+		/* Create the new supplier of a value. */
+		final Supplier<IHolder<BoundContainedType>> typeSupplier = () -> {
+			IHolder<BoundContainedType> oldHolder = boundHolder;
+
+			/* Bind the value if it hasn't been bound before. */
+			if(!holderBound) {
+				oldHolder = oldSupplier.get().unwrap(binder);
+			}
+
+			/* Apply all the pending actions. */
+			return pendingActions.reduceAux(oldHolder, (action, state) -> {
+				return state.transform(action);
+			}, (value) -> value);
+		};
+
+		return new BoundLazy<>(typeSupplier, bindr);
+	}
+
+	@Override
+	public <NewType> Function<BoundContainedType, IHolder<NewType>> lift(
+			final Function<BoundContainedType, NewType> func) {
+		if(func == null) throw new NullPointerException("Function to lift must not be null");
+
+		return (val) -> {
+			return new Lazy<>(func.apply(val));
+		};
+	}
+
+	@Override
+	public <MappedType> IHolder<MappedType> map(final Function<BoundContainedType, MappedType> mapper) {
+		if(mapper == null) throw new NullPointerException("Mapper must not be null");
+
+		/* Prepare a list of pending actions. */
+		final IList<UnaryOperator<BoundContainedType>> pendingActions = new FunctionalList<>();
+		actions.forEach(pendingActions::add);
+
+		/* Prepare the new supplier. */
+		final Supplier<MappedType> typeSupplier = () -> {
+			IHolder<BoundContainedType> oldHolder = boundHolder;
+
+			/* Bound the value if it hasn't been bound. */
+			if(!holderBound) {
+				oldHolder = oldSupplier.get().unwrap(binder);
+			}
+
+			/* Apply pending actions. */
+			return pendingActions.reduceAux(oldHolder.getValue(), (action, state) -> {
+				return action.apply(state);
+			}, (value) -> mapper.apply(value));
+		};
+
+		return new Lazy<>(typeSupplier);
+	}
+
+	@Override
+	public String toString() {
+		if(holderBound) return boundHolder.toString();
+
+		return "(unmaterialized)";
+	}
+
+	@Override
+	public IHolder<BoundContainedType> transform(final UnaryOperator<BoundContainedType> transformer) {
+		if(transformer == null) throw new NullPointerException("Transformer must not be null");
+
+		actions.add(transformer);
+
+		return this;
+	}
+
+	@Override
+	public <UnwrappedType> UnwrappedType unwrap(final Function<BoundContainedType, UnwrappedType> unwrapper) {
+		if(unwrapper == null) throw new NullPointerException("Unwrapper must not be null");
+
+		if(!holderBound) {
+			boundHolder = oldSupplier.get().unwrap(binder::apply);
+		}
+
+		return boundHolder.unwrap(unwrapper);
+	}
+}
diff --git a/src/main/java/bjc/data/internals/BoundLazyPair.java b/src/main/java/bjc/data/internals/BoundLazyPair.java
new file mode 100644
index 0000000..105b410
--- /dev/null
+++ b/src/main/java/bjc/data/internals/BoundLazyPair.java
@@ -0,0 +1,228 @@
+package bjc.data.internals;
+
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import bjc.data.IHolder;
+import bjc.data.IPair;
+import bjc.data.Identity;
+import bjc.data.LazyPair;
+
+/**
+ * Implements a lazy pair that has been bound.
+ *
+ * @author Ben Culkin
+ */
+@SuppressWarnings("javadoc")
+public class BoundLazyPair<OldLeft, OldRight, NewLeft, NewRight> implements IPair<NewLeft, NewRight> {
+	/* The supplier of the left value. */
+	private final Supplier<OldLeft> leftSupplier;
+	/* The supplier of the right value. */
+	private final Supplier<OldRight> rightSupplier;
+
+	/* The binder to transform values. */
+	private final BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>> binder;
+
+	/* The bound pair. */
+	private IPair<NewLeft, NewRight> boundPair;
+
+	/* Whether the pair has been bound yet. */
+	private boolean pairBound;
+
+	/**
+	 * Create a new bound lazy pair.
+	 *
+	 * @param leftSupp
+	 *        The supplier for the left value.
+	 *
+	 * @param rightSupp
+	 *        The supplier for the right value.
+	 *
+	 * @param bindr
+	 *        The function to use to bind the left and right into a new
+	 *        pair.
+	 */
+	public BoundLazyPair(final Supplier<OldLeft> leftSupp, final Supplier<OldRight> rightSupp,
+			final BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>> bindr) {
+		leftSupplier = leftSupp;
+		rightSupplier = rightSupp;
+		binder = bindr;
+	}
+
+	@Override
+	public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
+			final BiFunction<NewLeft, NewRight, IPair<BoundLeft, BoundRight>> bindr) {
+		if(bindr == null) throw new NullPointerException("Binder must not be null");
+
+		final IHolder<IPair<NewLeft, NewRight>> newPair = new Identity<>(boundPair);
+		final IHolder<Boolean> newPairMade = new Identity<>(pairBound);
+
+		final Supplier<NewLeft> leftSupp = () -> {
+			if(!newPairMade.getValue()) {
+				/*
+				 * If the pair hasn't been bound before, bind
+				 * it.
+				 */
+				newPair.replace(binder.apply(leftSupplier.get(), rightSupplier.get()));
+
+				newPairMade.replace(true);
+			}
+
+			return newPair.unwrap((pair) -> pair.getLeft());
+		};
+
+		final Supplier<NewRight> rightSupp = () -> {
+			if(!newPairMade.getValue()) {
+				/*
+				 * If the pair hasn't been bound before, bind
+				 * it.
+				 */
+				newPair.replace(binder.apply(leftSupplier.get(), rightSupplier.get()));
+
+				newPairMade.replace(true);
+			}
+
+			return newPair.unwrap((pair) -> pair.getRight());
+		};
+
+		return new BoundLazyPair<>(leftSupp, rightSupp, bindr);
+	}
+
+	@Override
+	public <BoundLeft> IPair<BoundLeft, NewRight> bindLeft(
+			final Function<NewLeft, IPair<BoundLeft, NewRight>> leftBinder) {
+		if(leftBinder == null) throw new NullPointerException("Left binder must not be null");
+
+		final Supplier<NewLeft> leftSupp = () -> {
+			IPair<NewLeft, NewRight> newPair = boundPair;
+
+			if(!pairBound) {
+				/*
+				 * If the pair hasn't been bound before, bind
+				 * it.
+				 */
+				newPair = binder.apply(leftSupplier.get(), rightSupplier.get());
+			}
+
+			return newPair.getLeft();
+		};
+
+		return new HalfBoundLazyPair<>(leftSupp, leftBinder);
+	}
+
+	@Override
+	public <BoundRight> IPair<NewLeft, BoundRight> bindRight(
+			final Function<NewRight, IPair<NewLeft, BoundRight>> rightBinder) {
+		if(rightBinder == null) throw new NullPointerException("Right binder must not be null");
+
+		final Supplier<NewRight> rightSupp = () -> {
+			IPair<NewLeft, NewRight> newPair = boundPair;
+
+			if(!pairBound) {
+				/*
+				 * If the pair hasn't been bound before, bind
+				 * it.
+				 */
+				newPair = binder.apply(leftSupplier.get(), rightSupplier.get());
+			}
+
+			return newPair.getRight();
+		};
+
+		return new HalfBoundLazyPair<>(rightSupp, rightBinder);
+	}
+
+	@Override
+	public <OtherLeft, OtherRight, CombinedLeft, CombinedRight> IPair<CombinedLeft, CombinedRight> combine(
+			final IPair<OtherLeft, OtherRight> otherPair,
+			final BiFunction<NewLeft, OtherLeft, CombinedLeft> leftCombiner,
+			final BiFunction<NewRight, OtherRight, CombinedRight> rightCombiner) {
+		if(otherPair == null) {
+			throw new NullPointerException("Other pair must not be null");
+		} else if(leftCombiner == null) {
+			throw new NullPointerException("Left combiner must not be null");
+		} else if(rightCombiner == null) {
+			throw new NullPointerException("Right combiner must not be null");
+		}
+
+		return otherPair.bind((otherLeft, otherRight) -> {
+			return bind((leftVal, rightVal) -> {
+				CombinedLeft cLeft = leftCombiner.apply(leftVal, otherLeft);
+				CombinedRight cRight = rightCombiner.apply(rightVal, otherRight);
+
+				return new LazyPair<>(cLeft, cRight);
+			});
+		});
+	}
+
+	@Override
+	public <NewLeftType> IPair<NewLeftType, NewRight> mapLeft(final Function<NewLeft, NewLeftType> mapper) {
+		if(mapper == null) throw new NullPointerException("Mapper must not be null");
+
+		final Supplier<NewLeftType> leftSupp = () -> {
+			if(!pairBound) {
+				final NewLeft leftVal = binder.apply(leftSupplier.get(), rightSupplier.get()).getLeft();
+
+				return mapper.apply(leftVal);
+			}
+
+			return mapper.apply(boundPair.getLeft());
+		};
+
+		final Supplier<NewRight> rightSupp = () -> {
+			if(!pairBound) return binder.apply(leftSupplier.get(), rightSupplier.get()).getRight();
+
+			return boundPair.getRight();
+		};
+
+		return new LazyPair<>(leftSupp, rightSupp);
+	}
+
+	@Override
+	public <NewRightType> IPair<NewLeft, NewRightType> mapRight(final Function<NewRight, NewRightType> mapper) {
+		if(mapper == null) throw new NullPointerException("Mapper must not be null");
+
+		final Supplier<NewLeft> leftSupp = () -> {
+			if(!pairBound) return binder.apply(leftSupplier.get(), rightSupplier.get()).getLeft();
+
+			return boundPair.getLeft();
+		};
+
+		final Supplier<NewRightType> rightSupp = () -> {
+			if(!pairBound) {
+				final NewRight rightVal = binder.apply(leftSupplier.get(), rightSupplier.get())
+						.getRight();
+
+				return mapper.apply(rightVal);
+			}
+
+			return mapper.apply(boundPair.getRight());
+		};
+
+		return new LazyPair<>(leftSupp, rightSupp);
+	}
+
+	@Override
+	public <MergedType> MergedType merge(final BiFunction<NewLeft, NewRight, MergedType> merger) {
+		if(merger == null) throw new NullPointerException("Merger must not be null");
+
+		if(!pairBound) {
+			/*
+			 * If the pair isn't bound yet, bind it.
+			 */
+			boundPair = binder.apply(leftSupplier.get(), rightSupplier.get());
+
+			pairBound = true;
+		}
+
+		return boundPair.merge(merger);
+	}
+
+	@Override
+	public String toString() {
+		if(pairBound) return boundPair.toString();
+
+		return "(un-materialized)";
+	}
+}
diff --git a/src/main/java/bjc/data/internals/BoundListHolder.java b/src/main/java/bjc/data/internals/BoundListHolder.java
new file mode 100644
index 0000000..8f8cab4
--- /dev/null
+++ b/src/main/java/bjc/data/internals/BoundListHolder.java
@@ -0,0 +1,81 @@
+package bjc.data.internals;
+
+import java.util.function.Function;
+import java.util.function.UnaryOperator;
+
+import bjc.data.IHolder;
+import bjc.data.ListHolder;
+import bjc.funcdata.IList;
+
+/**
+ * Holds a list, converted into a holder.
+ *
+ * @author Ben Culkin
+ */
+@SuppressWarnings("javadoc")
+public class BoundListHolder<ContainedType> implements IHolder<ContainedType> {
+	/* The list of contained holders. */
+	private final IList<IHolder<ContainedType>> heldHolders;
+
+	/**
+	 * Create a new list of holders.
+	 *
+	 * @param toHold
+	 *        The list of holders to, well, hold.
+	 */
+	public BoundListHolder(final IList<IHolder<ContainedType>> toHold) {
+		heldHolders = toHold;
+	}
+
+	@Override
+	public <BoundType> IHolder<BoundType> bind(final Function<ContainedType, IHolder<BoundType>> binder) {
+		if(binder == null) throw new NullPointerException("Binder must not be null");
+
+		final IList<IHolder<BoundType>> boundHolders = heldHolders.map((containedHolder) -> {
+			return containedHolder.bind(binder);
+		});
+
+		return new BoundListHolder<>(boundHolders);
+	}
+
+	@Override
+	public <NewType> Function<ContainedType, IHolder<NewType>> lift(final Function<ContainedType, NewType> func) {
+		if(func == null) throw new NullPointerException("Function to lift must not be null");
+
+		return (val) -> {
+			return new ListHolder<>(func.apply(val));
+		};
+	}
+
+	@Override
+	public <MappedType> IHolder<MappedType> map(final Function<ContainedType, MappedType> mapper) {
+		if(mapper == null) throw new NullPointerException("Mapper must not be null");
+
+		final IList<IHolder<MappedType>> mappedHolders = heldHolders.map((containedHolder) -> {
+			return containedHolder.map(mapper);
+		});
+
+		return new BoundListHolder<>(mappedHolders);
+	}
+
+	@Override
+	public IHolder<ContainedType> transform(final UnaryOperator<ContainedType> transformer) {
+		if(transformer == null) throw new NullPointerException("Transformer must not be null");
+
+		heldHolders.forEach((containedHolder) -> {
+			containedHolder.transform(transformer);
+		});
+
+		return this;
+	}
+
+	@Override
+	public <UnwrappedType> UnwrappedType unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
+		if(unwrapper == null) throw new NullPointerException("Unwrapper must not be null");
+
+		/*
+		 * @NOTE Is there another way we could want to do this?
+		 */
+		return heldHolders.randItem().unwrap(unwrapper);
+	}
+}
diff --git a/src/main/java/bjc/data/internals/HalfBoundLazyPair.java b/src/main/java/bjc/data/internals/HalfBoundLazyPair.java
new file mode 100644
index 0000000..4f28012
--- /dev/null
+++ b/src/main/java/bjc/data/internals/HalfBoundLazyPair.java
@@ -0,0 +1,177 @@
+package bjc.data.internals;
+
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import bjc.data.IHolder;
+import bjc.data.IPair;
+import bjc.data.Identity;
+import bjc.data.LazyPair;
+
+/*
+ * @NOTE
+ * 	I am not convinced that this code works correctly. Tests should be
+ * 	written to make sure things only ever get instantiated once.
+ *
+ * 	Namely, my main concern is to whether the places that bind the pair
+ * 	without setting pairBound are doing the right thing.
+ */
+/**
+ * A lazy pair, with only one side bound.
+ *
+ * @author Ben Culkin
+ */
+@SuppressWarnings("javadoc")
+public class HalfBoundLazyPair<OldType, NewLeft, NewRight> implements IPair<NewLeft, NewRight> {
+	/* The supplier of the old value. */
+	private final Supplier<OldType> oldSupplier;
+
+	/* The function to transform the old value into a new pair. */
+	private final Function<OldType, IPair<NewLeft, NewRight>> binder;
+
+	/* The new bound pair. */
+	private IPair<NewLeft, NewRight> boundPair;
+	/* Has the pair been bound yet or not? */
+	private boolean pairBound;
+
+	/**
+	 * Create a new half-bound lazy pair.
+	 *
+	 * @param oldSupp
+	 *        The supplier of the old value.
+	 *
+	 * @param bindr
+	 *        The function to use to create the pair from the old value.
+	 */
+	public HalfBoundLazyPair(final Supplier<OldType> oldSupp,
+			final Function<OldType, IPair<NewLeft, NewRight>> bindr) {
+		oldSupplier = oldSupp;
+		binder = bindr;
+	}
+
+	@Override
+	public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
+			final BiFunction<NewLeft, NewRight, IPair<BoundLeft, BoundRight>> bindr) {
+		final IHolder<IPair<NewLeft, NewRight>> newPair = new Identity<>(boundPair);
+		final IHolder<Boolean> newPairMade = new Identity<>(pairBound);
+
+		final Supplier<NewLeft> leftSupp = () -> {
+			if(!newPairMade.getValue()) {
+				/* Bind the pair if it hasn't been bound yet. */
+				newPair.replace(binder.apply(oldSupplier.get()));
+				newPairMade.replace(true);
+			}
+
+			return newPair.unwrap((pair) -> pair.getLeft());
+		};
+
+		final Supplier<NewRight> rightSupp = () -> {
+			if(!newPairMade.getValue()) {
+				/* Bind the pair if it hasn't been bound yet. */
+				newPair.replace(binder.apply(oldSupplier.get()));
+				newPairMade.replace(true);
+			}
+
+			return newPair.unwrap((pair) -> pair.getRight());
+		};
+
+		return new BoundLazyPair<>(leftSupp, rightSupp, bindr);
+	}
+
+	@Override
+	public <BoundLeft> IPair<BoundLeft, NewRight> bindLeft(
+			final Function<NewLeft, IPair<BoundLeft, NewRight>> leftBinder) {
+		final Supplier<NewLeft> leftSupp = () -> {
+			IPair<NewLeft, NewRight> newPair = boundPair;
+
+			if(!pairBound) {
+				newPair = binder.apply(oldSupplier.get());
+			}
+
+			return newPair.getLeft();
+		};
+
+		return new HalfBoundLazyPair<>(leftSupp, leftBinder);
+	}
+
+	@Override
+	public <BoundRight> IPair<NewLeft, BoundRight> bindRight(
+			final Function<NewRight, IPair<NewLeft, BoundRight>> rightBinder) {
+		final Supplier<NewRight> rightSupp = () -> {
+			IPair<NewLeft, NewRight> newPair = boundPair;
+
+			if(!pairBound) {
+				newPair = binder.apply(oldSupplier.get());
+			}
+
+			return newPair.getRight();
+		};
+
+		return new HalfBoundLazyPair<>(rightSupp, rightBinder);
+	}
+
+	@Override
+	public <OtherLeft, OtherRight, CombinedLeft, CombinedRight> IPair<CombinedLeft, CombinedRight> combine(
+			final IPair<OtherLeft, OtherRight> otherPair,
+			final BiFunction<NewLeft, OtherLeft, CombinedLeft> leftCombiner,
+			final BiFunction<NewRight, OtherRight, CombinedRight> rightCombiner) {
+		return otherPair.bind((otherLeft, otherRight) -> {
+			return bind((leftVal, rightVal) -> {
+				CombinedLeft cLeft = leftCombiner.apply(leftVal, otherLeft);
+				CombinedRight cRight = rightCombiner.apply(rightVal, otherRight);
+
+				return new LazyPair<>(cLeft, cRight);
+			});
+		});
+	}
+
+	@Override
+	public <NewLeftType> IPair<NewLeftType, NewRight> mapLeft(final Function<NewLeft, NewLeftType> mapper) {
+		final Supplier<NewLeftType> leftSupp = () -> {
+			if(pairBound) return mapper.apply(boundPair.getLeft());
+
+			final NewLeft leftVal = binder.apply(oldSupplier.get()).getLeft();
+
+			return mapper.apply(leftVal);
+		};
+
+		final Supplier<NewRight> rightSupp = () -> {
+			if(pairBound) return boundPair.getRight();
+
+			return binder.apply(oldSupplier.get()).getRight();
+		};
+
+		return new LazyPair<>(leftSupp, rightSupp);
+	}
+
+	@Override
+	public <NewRightType> IPair<NewLeft, NewRightType> mapRight(final Function<NewRight, NewRightType> mapper) {
+		final Supplier<NewLeft> leftSupp = () -> {
+			if(pairBound) return boundPair.getLeft();
+
+			return binder.apply(oldSupplier.get()).getLeft();
+		};
+
+		final Supplier<NewRightType> rightSupp = () -> {
+			if(pairBound) return mapper.apply(boundPair.getRight());
+
+			final NewRight rightVal = binder.apply(oldSupplier.get()).getRight();
+
+			return mapper.apply(rightVal);
+		};
+
+		return new LazyPair<>(leftSupp, rightSupp);
+	}
+
+	@Override
+	public <MergedType> MergedType merge(final BiFunction<NewLeft, NewRight, MergedType> merger) {
+		if(!pairBound) {
+			boundPair = binder.apply(oldSupplier.get());
+
+			pairBound = true;
+		}
+
+		return boundPair.merge(merger);
+	}
+}
diff --git a/src/main/java/bjc/data/internals/WrappedLazy.java b/src/main/java/bjc/data/internals/WrappedLazy.java
new file mode 100644
index 0000000..17d2309
--- /dev/null
+++ b/src/main/java/bjc/data/internals/WrappedLazy.java
@@ -0,0 +1,83 @@
+package bjc.data.internals;
+
+import java.util.function.Function;
+import java.util.function.UnaryOperator;
+
+import bjc.data.IHolder;
+import bjc.data.Lazy;
+
+/**
+ * A wrapped lazy value.
+ *
+ * @author Ben Culkin
+ * @param <ContainedType>
+ *        The type of the wrapped value.
+ */
+public class WrappedLazy<ContainedType> implements IHolder<ContainedType> {
+	/* Held value. */
+	private final IHolder<IHolder<ContainedType>> held;
+
+	/**
+	 * Create a new wrapped lazy value.
+	 *
+	 * @param wrappedHolder
+	 *        The holder to make lazy.
+	 */
+	public WrappedLazy(final IHolder<ContainedType> wrappedHolder) {
+		held = new Lazy<>(wrappedHolder);
+	}
+
+	/*
+	 * This has an extra parameter, because otherwise it erases to the same
+	 * as the public one.
+	 *
+	 * This is a case where reified generics would be useful, because then
+	 * the compiler could know which one we meant without the dummy
+	 * parameter.
+	 */
+	private WrappedLazy(final IHolder<IHolder<ContainedType>> wrappedHolder,
+			@SuppressWarnings("unused") final boolean dummy) {
+		held = wrappedHolder;
+	}
+
+	@Override
+	public <BoundType> IHolder<BoundType> bind(final Function<ContainedType, IHolder<BoundType>> binder) {
+		final IHolder<IHolder<BoundType>> newHolder = held.map((containedHolder) -> {
+			return containedHolder.bind(binder);
+		});
+
+		return new WrappedLazy<>(newHolder, false);
+	}
+
+	@Override
+	public <NewType> Function<ContainedType, IHolder<NewType>> lift(final Function<ContainedType, NewType> func) {
+		return (val) -> {
+			return new Lazy<>(func.apply(val));
+		};
+	}
+
+	@Override
+	public <MappedType> IHolder<MappedType> map(final Function<ContainedType, MappedType> mapper) {
+		final IHolder<IHolder<MappedType>> newHolder = held.map((containedHolder) -> {
+			return containedHolder.map(mapper);
+		});
+
+		return new WrappedLazy<>(newHolder, false);
+	}
+
+	@Override
+	public IHolder<ContainedType> transform(final UnaryOperator<ContainedType> transformer) {
+		held.transform((containedHolder) -> {
+			return containedHolder.transform(transformer);
+		});
+
+		return this;
+	}
+
+	@Override
+	public <UnwrappedType> UnwrappedType unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
+		return held.unwrap((containedHolder) -> {
+			return containedHolder.unwrap(unwrapper);
+		});
+	}
+}
diff --git a/src/main/java/bjc/data/internals/WrappedOption.java b/src/main/java/bjc/data/internals/WrappedOption.java
new file mode 100644
index 0000000..eb4d120
--- /dev/null
+++ b/src/main/java/bjc/data/internals/WrappedOption.java
@@ -0,0 +1,96 @@
+package bjc.data.internals;
+
+import java.util.function.Function;
+import java.util.function.UnaryOperator;
+
+import bjc.data.IHolder;
+import bjc.data.Option;
+
+/**
+ * A wrapped optional value.
+ *
+ * @author Ben Culkin.
+ * @param <ContainedType>
+ *        The wrapped type.
+ */
+public class WrappedOption<ContainedType> implements IHolder<ContainedType> {
+	/* The held value. */
+	private final IHolder<IHolder<ContainedType>> held;
+
+	/**
+	 * Create a new wrapped option.
+	 *
+	 * @param seedValue
+	 *        The value to wrap.
+	 */
+	public WrappedOption(final IHolder<ContainedType> seedValue) {
+		held = new Option<>(seedValue);
+	}
+
+	/*
+	 * The dummy parameter is to ensure the compiler can pick the right
+	 * method, because without this method erases to the same type as the
+	 * public one.
+	 */
+	private WrappedOption(final IHolder<IHolder<ContainedType>> toHold,
+			@SuppressWarnings("unused") final boolean dummy) {
+		held = toHold;
+	}
+
+	@Override
+	public <BoundType> IHolder<BoundType> bind(final Function<ContainedType, IHolder<BoundType>> binder) {
+		final IHolder<IHolder<BoundType>> newHolder = held.map((containedHolder) -> {
+			return containedHolder.bind((containedValue) -> {
+				if(containedValue == null) return new Option<>(null);
+
+				return binder.apply(containedValue);
+			});
+		});
+
+		return new WrappedOption<>(newHolder, false);
+	}
+
+	@Override
+	public <NewType> Function<ContainedType, IHolder<NewType>> lift(final Function<ContainedType, NewType> func) {
+		return (val) -> {
+			return new Option<>(func.apply(val));
+		};
+	}
+
+	@Override
+	public <MappedType> IHolder<MappedType> map(final Function<ContainedType, MappedType> mapper) {
+		final IHolder<IHolder<MappedType>> newHolder = held.map((containedHolder) -> {
+			return containedHolder.map((containedValue) -> {
+				if(containedValue == null) return null;
+
+				return mapper.apply(containedValue);
+			});
+		});
+
+		return new WrappedOption<>(newHolder, false);
+	}
+
+	@Override
+	public IHolder<ContainedType> transform(final UnaryOperator<ContainedType> transformer) {
+		held.transform((containedHolder) -> {
+			return containedHolder.transform((containedValue) -> {
+				if(containedValue == null) return null;
+
+				return transformer.apply(containedValue);
+			});
+		});
+
+		return this;
+	}
+
+	@Override
+	public <UnwrappedType> UnwrappedType unwrap(final Function<ContainedType, UnwrappedType> unwrapper) {
+		return held.unwrap((containedHolder) -> {
+			return containedHolder.unwrap((containedValue) -> {
+				if(containedValue == null) return null;
+
+				return unwrapper.apply(containedValue);
+			});
+		});
+	}
+}