Elm ：从字符串列表中提取记录值

Question

我尝试制作一个函数，它接受记录和属性名称列表并将值作为字符串列表返回：

Model -> (List String) -> (List String)

目标是以后能够将记录动态呈现到 HTML 表中：

Model -> (List String) -> (Html Cmd)

我成功实现了这个：

import Html exposing (text)

type Field
  = FieldInt Int
  | FieldString String

type alias Model = 
  { name: Field
  , age: Field
  }

user1 = Model (FieldString "foo") (FieldInt 3)

field2text: Field -> String
field2text field =
  case field of
    FieldInt value ->
      toString value
    FieldString value ->
      value

updateModel: (List (a -> Field)) -> (List String)
model2values fns model =
  List.map (\fn -> field2text <| fn model) fns

main =
  text <| toString (model2values [.name, .age] user1)

如何更新model2values 函数以将最后一行更改为：

main =
  text <| toString (model2values ["name", "age"] user1)

Answer 1

没有什么好办法，所以只剩下：

toFieldGetter : String -> (a -> Field)
toFieldGetter : name = 
    case name of 
        "name" -> .name
        ...

model2values_ = model2values << List.map toFieldGetter

main =
  text <| toString (model2values_ ["name", "age"] user1)