我有一段Elm代码(对于brievity,省略了getProjectView函数):
type Model = Maybe List Project
model : Model
model = Nothing
getView : Model -> Html any
getView model =
case model of
Just projects ->
ul [] (List.map getProjectView projects)
Nothing -> p [] [ text "Still loading..." ]
-- TYPE MISMATCH --------- E:\dev\irrelephant-code\client\elm\Views\Projects.elm
Tag `Maybe.Just` is causing problems in this pattern match.
32| Just projects ->
^^^^^^^^^^^^^
The pattern matches things of type:
Maybe a
But the values it will actually be trying to match are:
Model
表明编译器无法推断
Nothing
是类型的值
Model
(这反过来又是类型的别名
Maybe List Project
).
我正在使用elm v0.18.0
