Naming convention of @FunctionalInterface

Question

By convention, types should be named by nouns, that's ok. However, @FunctionalInterface is a special type - object type that acts like function/method. In case of function I feel like it's more natural to choose a verb e.g. decorate.apply(o) instead of noun decorator.apply(o). And there are also nouns expressing an activities e.g. decoration.apply(o).

If I look at java.util.function package all the functions are named by nouns: Function, Operator, Consumer, Supplier, ... Should I prefer nouns, verbs or nouns expressing verbs?

UPDATE

Sometimes, we can get little help with factory method returning an object/function:

// toList factory returning Collector instance
list.stream().filter(...).collect(toList()); 

Answer 1

@FunctionalInterface can mark only types (classes, interfaces, annotations, enums).

To name a type you should use a noun, while for a method you need a verb.

Classes

Class names should be nouns, in mixed case with the first letter of each internal word capitalized. Try to keep your class names simple and descriptive. Use whole words-avoid acronyms and abbreviations (unless the abbreviation is much more widely used than the long form, such as URL or HTML).

class Raster; 
class ImageSprite;

Methods

Methods should be verbs, in mixed case with the first letter lowercase, with the first letter of each internal word capitalized.

run(); 
runFast(); 
getBackground();

^{Naming Conventions, Oracle}

Here's an example of how I would define a functional interface.

@FunctionalInterface
interface Decorator {

    void decorate();

}

In code, it looks readable.

Decorator decorator = () -> {};
decorator.decorate();

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My thoughts on "decorator vs decoration":

"Decoration" is more about describing the process/result, while "Decorator" is a mechanism/tool/means to start that process/to obtain that result.

If I saw the Decoration class in code, I would think about a collection of decoration stuff (like ornaments, paints, wallpapers) rather than a person who actually decorate.

If I saw Decorator or Painter, I would be expecting methods like decorate() or paint() because that's what they can/should do.

Compare suppliance/supplier -> get() and consumption/consumer -> accept(t).