Split Result list into oks and errors

mapPartition.fs

let mapPartition (partitioner : 'T -> Result<'U1, 'U2>) list : 'U1 list * 'U2 list =


    // OPTIMIZATION : If the input list is empty, immediately return empty results.
    if List.isEmpty list then
        [], []
    else
        // Mutable variables are used here instead of List.fold for maximum performance.
        let mutable list = list
        let mutable resultList1 = []
        let mutable resultList2 = []

        // Partition the list, consing the elements onto the list
        // specified by the partition function.
        while not <| List.isEmpty list do
            match partitioner <| List.head list with
            | Ok element ->
                resultList1 <- element :: resultList1
            | Error element ->
                resultList2 <- element :: resultList2

            // Remove the first element from the input list.
            list <- List.tail list

        // Reverse the result lists and return them.
        List.rev resultList1, List.rev resultList2