度量单位类型参数

[<Measure>] 属性可用于类型参数，以声明与度量单位相关的通用类型：

type CylinderSize<[<Measure>] 'u> =
    { Radius : float<'u>
      Height : float<'u> }

测试用法：

open Microsoft.FSharp.Data.UnitSystems.SI.UnitSymbols

/// This has type CylinderSize<m>.
let testCylinder =
    { Radius = 14.<m>
      Height =  1.<m> }