+

Addition on numbers and strings.

1 + 2 gives 3.

"foo" + "bar" gives "foobar".

"foo" + something where something is any object instance is equivalent to "foo" + something.toString() in Java.

-

Subtraction on numbers.

4 - 1 gives 3.

*

Multiplication on numbers and strings.

2 * 2 gives 4.

"a" * 3 gives "aaa".

/

Division on numbers.

4 / 2 gives 2.

%

Modulo on numbers.

4 % 2 gives 0, 3 % 2 gives 1.

"<", "<=", "==", "!=", ">", ">="

Comparison between numbers and objects that implement java.lang.Comparable. == is equivalent to calling Object#equals(Object) in Java.

1 < 2 gives true.

is, isnt

Comparison of reference equality.

a is b gives true only if a and b reference the same object instance.

and, or, not

Boolean operators. not is of course a unary operator.

true and true gives true, not(true) gives false.

oftype

Checks the type of an object instance, equivalent to the instanceof operator in Java.

("plop" oftype String.class) gives true.

orIfNull

Evaluates an expression and returns the value of another one if null.

null orIfNull "a" gives "a". foo() orIfNull 0 gives the value of calling foo(), or 0 if foo() returns null.