SplitEvery (New version, no explicit recursion)

open System.Linq

let repeat x = Seq.initInfinite (fun _ -> x)

let scan = Seq.scan

let iterate f x = scan (fun l _ -> f l) x (repeat x)

let any = Enumerable.Any

let take n = fun xs -> Enumerable.Take (xs, n)

let skip n = fun xs -> Enumerable.Skip (xs, n)

let unfold h p t =  iterate t >> Seq.takeWhile p >> Seq.map h 

let splitAt n = unfold (take n) any (skip n)