combine applicatives.fs

let validateNumber n = 
    returnM n 
    <* evenNumber n
    <* notEqual 3 n

let validateNumber' n = 
    returnM (fun _ _ -> n) 
    <*> evenNumber n
    <*> notEqual 3 n

let validateNumber'' n =
    returnM (konst2 n) 
    <*> evenNumber n
    <*> notEqual 3 n

let validateNumber''' n =
    konst2 n
    <!> evenNumber n
    <*> notEqual 3 n

let validateNumber'''' n =
    returnM (konst2 n) 
    |> ap (evenNumber n)
    |> ap (notEqual 3 n)

let validateNumber''''' n = 
    konst n 
    <!> (evenNumber >=> notEqual 3) n

let validateNumber'''''' n = 
    returnM n <* sequence [evenNumber n; notEqual 3 n]