Task

Calculate the value of   e.



(e   is also known as   Euler's number   and   Napier's constant.)



See details: Calculating the value of e

(:n (n 0 ==) ((0)) (-1 () ((succ dup) dip append) n times) if) :iota
(iota 'succ '* map-reduce) :factorial
 
20 iota (factorial 1 swap /) '+ map-reduce print