parameterized_pattern_for_array_tail

let (|Array|_|) pattern toMatch =
    let patternLength = Array.length pattern
    let toMatchLength = Array.length toMatch
    let tailLength = toMatchLength - patternLength

    if patternLength > toMatchLength then
        None
    else
        let firstElementsAreEqual = [ 0 .. (patternLength - 1) ] |> Seq.forall (fun i -> pattern.[i] = toMatch.[i])
        if firstElementsAreEqual then
            Some(Array.sub toMatch patternLength tailLength)
        else
            None
        
match [|1;2;3|] with
| Array [|1|] tail -> sprintf "bingo %i" (tail |> Array.sum) // the tail is [|2;3|]