Naming Collection Extensions for clarity

Question

Introducing some of the goodness of collection operations to our codebase without adding a new external library dependency, we are adding these methods to our utility package.

static public List<T> filter(List<T> source, Predicate<T> filter);
static <Y,T> public List<Y> transform(List<T> source, Mutator<Y,T> filter);
static public boolean exists(List<T> source, Predicate<T> filter);
static public T findFirst(List<T> source, Predicate<T> filter);
static public boolean trueForAll(List<T> source, Predicate<T> filter);

With the attendant interfaces

public interface Predicate<T> { public boolean apply(T item); }
public interface Mutator<T,Y> { public Y apply(T item); }

So the questions:

• Is Filters a good name for the class containing the extensions? If not, a better?
• Is Mutator<T,Y> appropriately named?
• Should I prefer map to transform and reduce to filter?
• Are there any important set-based functions that I've forgotten to include in the library class?

Edited to add: A significant argument I have against map (and thus in favor of transform) is that map has significant semantic load due to the many uses for java.util.Map

Answer 1

Are there any important set-based functions that I've forgotten to include in the library class?

For higher-order collection functions I use the approach outlined by Adrian Kuhn in his article "Pimp My Foreach".

Some of these you've already got, but thought I'd throw them out there anyway:

• AllSatisfy
• AnySatisfy
• Cardinality
• Collect
• Count
• CutPieces
• Detect
• Fold
• GroupedBy
• IndexOf
• Inject
• Reject
• Select