Find a subset of a sequence or an array in F# given a source collection and a target collection

gistfile1.txt

module x

let list = [-1;0;1;2;3;4;5;6;7;8;9] |> List.toArray
let target = [1;2;3] |> List.toArray
let nope = [4;1;2] |> List.toArray

/// <summary>
/// Sequenes are basically IEnumerable, so you can't do structural equality on them
/// this is why they are converted to an F# list before doing comparison, otherwise
/// their references are compared
/// </summary>
/// <param name="source"></param>
/// <param name="target"></param>
let rec seqHasSubset source target =    
    let eq seq1 seq2 = (seq1 |> Seq.toList) = (seq2 |> Seq.toList)

    match Seq.length source with 
        | x when x < Seq.length target -> false
        | _ when Seq.take (Seq.length target) source |> eq <| target -> true
        | _ -> seqHasSubset (Seq.skip 1 source) target

/// <summary>
/// Arrays however, have structural equality AND support array slicing
/// (which lists and sequences do not).  If you have an array you can do something
/// like this
/// </summary>
/// <param name="source"></param>
/// <param name="target"></param>
let rec arrayHasSubset (source:'a []) (target : 'a [])= 
    match source.Length with 
        | x when x < target.Length -> false
        | _ when source.[0..target.Length - 1] = target -> true
        | _ -> arrayHasSubset source.[1..] target