generates a function based on a partial apply
(partial func arg+)
Returns a new Function whose initial arguments are pre-bound to those provided. When that Function is invoked, any provided arguments will simply be appended to the pre-bound arguments before calling the original Function.
(define plus10 (partial + 4 6)) (plus10 9)
This example will return 19 as though
(+ 4 6 9) were called.