Static and runtime types: Correct Solution

Given the following type declarations:

public interface Lurmi {
    public Lurmi prafti(Lurmi eu);
}

public class Dosm implements Lurmi {
    public Lurmi prafti(Lurmi eu) {
        return eu;
    }
}

public class Rophlin implements Lurmi {
    public Lurmi prafti(Lurmi eu) {
        return new Rophlin();
    }
}

...and given the following setup code:

Rophlin foo = new Rophlin();
Dosm bar = new Dosm();

Part 1

Draw an AST for the following expression, labeling the static type (a.k.a. compile-time type) of each node in the tree:

foo.prafti(foo.prafti(bar))

(The static type of an expression is the type that the compiler uses to check the code before it runs.)

Solution

Part 2

Draw an AST for the same expression, this time labeling the runtime type of each node in the tree.

(The runtime type of an expression is the type of the actual value that appears when the code runs.)

Solution

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