Imports System Imports uCalcSoftware Public Module Program Public Sub MyAreaCallback(ByVal cb As uCalc.Callback) Dim length = cb.Arg(1) Dim width = cb.Arg(2) cb.Return(length * width) End Sub Public Sub Main() Dim uc As New uCalc() '// The signature is defined, but the logic is provided by 'MyAreaCallback'. uc.DefineFunction("Area(x, y)", AddressOf MyAreaCallback) Console.WriteLine(uc.Eval("Area(3, 4)")) End Sub End Module