LISP is a prefix notation language. While it is true that you do
not need
parentheses if using prefix
notation and you restrict yourself
to only
binary operators, LISP extends its operators to be more
than binary. This extension requires the use of
parentheses for
grouping.
(/ (+ 2 3 4 5) 2)
is equivalent to
(2 + 3 + 4 + 5) / 2
The primary benefit of prefix notation here is that the function
or operator is at the start of the list, and the remainder of the list
is the argument to it. Mostly, its a different way of
thinking of how to deal with operations.