Seq.chunkBy.fs

module Seq =
    let chunkBy f source = 
        seq { 
            let chunk = ResizeArray()
            for x in source do
                if (chunk.Count <> 0) && (f x) then 
                    chunk.ToArray()
                    chunk.Clear()
                chunk.Add(x)
            if chunk.Count <> 0 then
                chunk.ToArray()
        }