some useful Project Euler functions

euler.fsx

let pair_multiply s1 s2 = 
    [ for x in s1 do 
        for y in s2 do 
            yield (x,y) ]

let enumerate (a:'a[]) =   
    Array.mapi (fun i x -> (i,x)) a   
    
let pandigital (n:int) = 
    let a = string(n).ToCharArray()
    pandigitalArray 
    |> Array.map (fun c -> Array.contains c a) 
    |> Array.fold (fun e acc -> e && acc) true
    
let sort_triple (a,b,c) =
    let sorted = Array.sort [| a;b;c |]
    (sorted.[0], sorted.[1], sorted.[2])