Imports System.Runtime.CompilerServices

Module Module1

    Sub Main()
        Dim rand As New Random
        Dim numbers = Enumerable.Range(0, 5000).Select(Function(n) rand.Next(Integer.MinValue, Integer.MaxValue)).Concat({Integer.MinValue, Integer.MaxValue}).
            Select(Function(r)
                       Dim bb() As Byte = BitConverter.GetBytes(r)
                       Return BitConverter.ToUInt32(bb, 0)
                   End Function).ToArray
        'numbers  is just an ienumerable.  it hasn't been iterated and has not generated values

        Dim numbersList = numbers.ToList
        Dim numbersArray = numbers.ToArray
        Dim evens = numbers.Where(Function(n) n Mod 2 = 0)
        'You will notice if you but a breakpoint here and examine these variables that you got different values in the ienumerables
        'Uncomment the .toarray in the numbers declaration
        'Try again.  Understand what is happening?
        'This is functional programming.  I defined something that will generate 5000 values and each value is an integer converted to a UInteger(UInt32)
        'CUInt(rand.Next(Integer.MinValue, Integer.MaxValue))
        'So .ToList,.ToArray, for each ...will iterate over the ienumerable and generate the right type if it is a to.. method.
        Dim doubles = {
            New With {.Values = numbers.Select(Function(n) CDbl(n)), .SourceType = numbers.GetType, .Name = NameOf(numbers)},
            New With {.Values = numbersArray.Select(Function(n) CDbl(n)), .SourceType = numbersArray.GetType, .Name = NameOf(numbersArray)},
            New With {.Values = evens.Select(Function(n) CDbl(n)), .SourceType = evens.GetType, .Name = NameOf(evens)}
        }.Select(Function(d) New With {.Values = d.Values, .Caption = $"{d.Name}- {d.SourceType.FullName}{Environment.NewLine}{vbTab}Value type- {d.Values.GetType.FullName}"})

        For Each dbl In doubles
            dbl.Values.Take(10).Dump(dbl.Caption)
        Next







        Dim lines = "It was the best of times, it was the worst of times, it was the age of wisdom,
it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light,
it was the season of Darkness, it was the spring of hope, it was the winter of despair …, we had nothing before us,
we were all going direct to Heaven, we were all going direct the other way …".Split(vbCrLf.ToCharArray, StringSplitOptions.RemoveEmptyEntries)

        Dim words = From w In lines.GetWords
                    Where w.ToLower.StartsWith("t")


        words = doubles.Select(Function(d) d.Caption).GetWords



        Dim range = Enumerable.Range(0, Integer.MaxValue \ 2)
        Dim EvenNums = range.IsMod(2)
        Dim even10s = EvenNums.IsMod(10)
        even10s.Take(20).Dump("Even Tens")


        Console.ReadKey()
    End Sub

    <Extension>
    Sub Dump(Of T)(items As IEnumerable(Of T), caption As String)
        Console.WriteLine(caption)
        For Each item In items
            Console.WriteLine(item)
        Next
        Console.WriteLine()
    End Sub
    <Extension>
    Function GetWords(strings As IEnumerable(Of String)) As IEnumerable(Of String)
        Return strings.SelectMany(Function(s) If(s, "").Split(" ".ToCharArray, StringSplitOptions.RemoveEmptyEntries))
    End Function

    'Could be done with where but I want to show how linq queries work
    <Extension()>
    Iterator Function IsMod(numbers As IEnumerable(Of Integer), Modulus As Integer) As IEnumerable(Of Integer)
        For Each num In numbers
            If num Mod Modulus = 0 Then Yield num
        Next
    End Function

End Module