FOLD<N> Macro

FOLD<N> macro enables operations on a list of values such as sum, avg, filter, zip, exists etc. The macro behaves like the fold or reduce function in other programming languages,

FOLD<N>(list, start, foldFunc)

Parameter	Description
N	Maximum number of iterations, up to 1000
list	List of values
start	Initial value
foldFunc	Folded function

The complexity of FOLD<N> corresponds to the complexity of foldFunc mutliplied by N plus extras.

Sum of Numbers

func sum(a:Int, b:Int) = a + b
let arr = [1,2,3,4,5]
FOLD<5>(arr, 0, sum)

Result: 15

Product of Numbers

func mult(a:Int, b:Int) = a * b
let arr = [1,2,3,4,5]
FOLD<5>(arr, 1, mult)

Result: 120

Filter

func filterStep(accumulated: List[Int], a: Int) =
   if (a % 2 == 0) then a :: accumulated else accumulated
let arr = [1,2,3,4,5]
FOLD<5>(arr, [], filterStep)

Result: [4, 2]