Question

榆树新手。使用榆木0.18。

这是一个非常简单的SPA，有12个按钮（每个按钮带有音符值）。单击该按钮，它将显示您单击的注释。

我想通过Put为按钮分配一个函数onClick，然后传递一个字符串参数note，用于更新模型。

这是我的代码：

import Html exposing (div, beginnerProgram, text, button)
import Html.Events exposing (onClick)
import List exposing (..)

main =
  beginnerProgram { model = model, update = update, view = view }

-- model
model =
  { key = "C" }

keys =
  ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"]

-- update
type Action = Put

update msg model =
  case msg note of
    Put ->
      { model | key = note }

-- view
makeButton note =
  button [ onClick Put note ] [text note]

view model =
  div [] [
    div [] [text (toString model.key)],
    div [] (map makeButton keys)
  ]

我收到此错误：

-- NAMING ERROR -------------------------------------------------- musiccalc.elm

Cannot find variable `note`

19|   case msg note of

Answer 1

知道了，你输入了动作，然后在进入item之前先评估。

stores

使用elm 0.18中的参数更新模型

1 个答案: