Extensions.vb

<Extension>
Public Iterator Function ChunkBySumIf(Of T)(source As IEnumerable(Of T), selector As System.Func(Of T, Double), predicate As System.Func(Of Double, Boolean)) As IEnumerable(Of IEnumerable(Of T))

    If source Is Nothing Then Throw New ArgumentNullException(NameOf(source))
    If selector Is Nothing Then Throw New ArgumentNullException(NameOf(selector))
    If predicate Is Nothing Then Throw New ArgumentNullException(NameOf(predicate))

    Using enumerator = source.GetEnumerator()
        Dim values As List(Of T) = Nothing

        While enumerator.MoveNext
            values = If(values, New List(Of T))

            If predicate(values.Sum(selector) + selector(enumerator.Current)) Then
                values.Add(enumerator.Current)
            Else
                Yield values.Hide()
                values = New List(Of T)({enumerator.Current})
            End If

        End While

        If values?.Count > 0 Then
            Yield values
        End If
    End Using

End Function

<Extension>
Public Iterator Function Hide(Of T)(source As IEnumerable(Of T)) As IEnumerable(Of T)

    If source Is Nothing Then Throw New ArgumentNullException(NameOf(source))

    Using enumerator = source.GetEnumerator()
        While enumerator.MoveNext
            Yield enumerator.Current
        End While
    End Using

End Function