Check if an element is within a sequence

Question

how to check if an element is contained within a sequence? I expected some Seq.contains, but i could not find it. Thanks

EDIT: Or, for an easier tas

Answer 1

(Another question, another answer.)

This works, but I don't think that it's the most idomatic way to do it - (you'll need to wait until the US wakes up to find out):

let s1 = seq [ 1; 2; 3; 4 ]
let s2 = seq [ 3; 4; 5; 6 ]

seq {
    for a in s1 do
        if not (Seq.exists (fun n -> n = a) s2) then
            yield a
        }