问题 用f＃报废你的锅炉

从来没听说过;如果没有内置于语言/编译器的支持，我希望唯一的替代方案是基于反射的版本。 （我不知道怎么做 Uniplate中 实施 - 你呢？）

这是基于原始演示文稿示例的基于反射的版本的代码。我没有深入考虑它的局限性，但这比我想象的要简单得多。

type Company = C of Dept list
and Dept = D of Name * Manager * SubUnit list
and SubUnit = | PU of Employee | DU of Dept
and Employee = E of Person * Salary
and Person = P of Name * Address
and Salary = S of float
and Manager = Employee
and Name = string
and Address = string

let data = C [D("Research",E(P("Fred","123 Rose"),S 10.0),
                  [PU(E(P("Bill","15 Oak"),S 5.0))])]
printfn "%A" data

open Microsoft.FSharp.Reflection 
let everywhere<'a,'b>(f:'a->'a, src:'b) =   // '
    let ft = typeof<'a>             // '
    let rec traverse (o:obj) =
        let ot = o.GetType()
        if ft = ot then
            f (o :?> 'a) |> box    // '
        elif FSharpType.IsUnion(ot) then
            let info,vals = FSharpValue.GetUnionFields(o, ot)
            FSharpValue.MakeUnion(info, vals |> Array.map traverse)
        else 
            o
    traverse src :?> 'b       // '

let incS (S x) = S(x+1.0) 

let newData = everywhere(incS, data)
printfn "%A" newData

该 everywhere 函数遍历任意DU的整个结构并应用该函数 f 到每个节点类型 f 继续工作，让所有其他节点保持原样。

从来没听说过;如果没有内置于语言/编译器的支持，我希望唯一的替代方案是基于反射的版本。 （我不知道怎么做 Uniplate中 实施 - 你呢？）

这是基于原始演示文稿示例的基于反射的版本的代码。我没有深入考虑它的局限性，但这比我想象的要简单得多。

type Company = C of Dept list
and Dept = D of Name * Manager * SubUnit list
and SubUnit = | PU of Employee | DU of Dept
and Employee = E of Person * Salary
and Person = P of Name * Address
and Salary = S of float
and Manager = Employee
and Name = string
and Address = string

let data = C [D("Research",E(P("Fred","123 Rose"),S 10.0),
                  [PU(E(P("Bill","15 Oak"),S 5.0))])]
printfn "%A" data

open Microsoft.FSharp.Reflection 
let everywhere<'a,'b>(f:'a->'a, src:'b) =   // '
    let ft = typeof<'a>             // '
    let rec traverse (o:obj) =
        let ot = o.GetType()
        if ft = ot then
            f (o :?> 'a) |> box    // '
        elif FSharpType.IsUnion(ot) then
            let info,vals = FSharpValue.GetUnionFields(o, ot)
            FSharpValue.MakeUnion(info, vals |> Array.map traverse)
        else 
            o
    traverse src :?> 'b       // '

let incS (S x) = S(x+1.0) 

let newData = everywhere(incS, data)
printfn "%A" newData

该 everywhere 函数遍历任意DU的整个结构并应用该函数 f 到每个节点类型 f 继续工作，让所有其他节点保持原样。