Elm Dict中的校验值
试图检查水果的价值Elm Dict中的校验值,elm,Elm,试图检查水果的价值 fruit = Dict.fromList [ ( 1, { fruitIsGood = False } ) , ( 2, { fruitIsGood = False } ) , ( 3, { fruitIsGood = True } ) ] whichFruitIsGood : Dict.Dict number { fruitIsGood : Bool } -> String whichFruitIsGood fr
fruit =
Dict.fromList
[ ( 1, { fruitIsGood = False } )
, ( 2, { fruitIsGood = False } )
, ( 3, { fruitIsGood = True } )
]
whichFruitIsGood : Dict.Dict number { fruitIsGood : Bool } -> String
whichFruitIsGood fruit =
case get 0 fruit of
Nothing ->
Debug.crash "nothing found"
Just fruit ->
if fruit.fruitIsGood == True then
"Apple"
else
"I hate Fruit"
我不知道如何获取fruitIsGood道具或您在Elm中称之为的任何东西。首先,Debug.crash“nothing found”
不会为您提供任何有用的功能,不如返回nothing found
字符串
然后您只需要修复编译器指出的错误。它们主要是关于变量的,这些变量被多次定义。让我们将第一个函数重命名为fruits
:
fruits =
Dict.fromList
[ ( 1, { fruitIsGood = False } )
, ( 2, { fruitIsGood = False } )
, ( 3, { fruitIsGood = True } )
]
以及第二个函数中的变量:
whichFruitIsGood : Dict.Dict number { fruitIsGood : Bool } -> String
whichFruitIsGood fruit =
case get 3 fruit of
Nothing ->
"nothing found"
Just foundFruit ->
if foundFruit.fruitIsGood == True then
"Apple"
else
"I hate Fruit"
然后,您的代码将编译并返回未找到任何内容
这里有一个稍加修改的示例,它显示了实际运行的代码