Polyvariadic functions in F#

polyvariadic.fsx

// Unfortunatelly it stopped working in F# 4.1 after this PR https://github.com/Microsoft/visualfsharp/pull/1650
// Will ask to revert it

type FoldArgs<'t> = FoldArgs of ('t -> 't -> 't)

let inline foldArgs f (x:'t) (y:'t) :'rest = (FoldArgs f $ Unchecked.defaultof<'rest>) x y

type FoldArgs<'t> with
    static member inline ($) (FoldArgs f, _:'t-> 'rest) = fun (a:'t) -> f a >> foldArgs f
    static member        ($) (FoldArgs f, _:'t        ) = f


let x:int = foldArgs (+) 2 3 
let y:int = foldArgs (+) 2 3 4
let z:int = foldArgs (+) 2 3 4 5
let d:decimal = foldArgs (+) 2M 3M 4M
let e:string = foldArgs (+) "h" "e" "l" "l" "o"
let f:float  = foldArgs (+) 2. 3. 4.

let mult3Numbers a b c = a * b * c
let res2 = mult3Numbers 3 (foldArgs (+) 3 4) (foldArgs (+) 2 2 3 3)