The compiler uses arrays for lists instead of linked lists. It is a performance improvement compared with how functional compilers usually do it. And the langua

The compiler uses arrays for lists instead of linked lists. It is a performance improvement compared with how functional compilers usually do it. And the language is designed in such a way that rule writers manipulate whole lists at a time instead of one element at a time. A bit like array languages. It changes how the code is written compared with traditional functional code.