@time

The @time macro "starts a timer" at the beginning of the code, and "stops the timer" when the code finishes. Elapsed time and memory usage is returned.

@which

This macro doesn't allow the expression 2 + 2 to be evaluated at all. Instead, it reports which method would be used for these particular arguments. And it also tells you the source file that contains the method's definition, and the line number.

@show

Show an expression and result, returning the result

Defining Macro