如何从VB.NET中的多变量函数返回单数函数

Question

我有一个功能：

Public Function F(ByVal a As Double, ByVal b As Double,
                  ByVal c As Double, ByVal x As Double) As Double
  y = ax ^ 3 + bx ^ 2 + cx + d
  Return y
End Function

我怎样才能创建一个允许我读取参数a，b，c，d并返回一元函数的函数？例如，a = 1，b = 1，c = 3，d = 4：

Public Function F(ByVal x As Double) As Double
  y = 1x ^ 3 + 2x ^ 2 + 3x + 4
  Return y
End Function

或者换句话说，我怎么能创建一个返回类型

的函数的函数

Func(Of Double, Double)

Answer 1

使用lambda函数。

Public Function F(ByVal a As Double, ByVal b As Double, ByVal c As Double) As Func(of Double, Double)
    Return Function(ByVal x As Double) As Double
               Return ax ^ 3 + bx ^ 2 + cx + d
           End Function
End Function