Typing

Many languages such as Java and C use what is known as strong or static variable typing. This means that when you declare a variable in your application code you must define the variable type.

And I've forgot to mention that if you would like to declare types and have the compiler check their type for you, you can use the CHECK-TYPE macro which just expands to:

 (check-type place typespec)
 ==  (assert (typep place 'typespec) (place)
            'type-error :datum place :expected-type 'typespec)