I am new to elm and I'm working on the ElmBridge tutorial. I understand Html.App collapsed into Html and any Html.App imports need to refer to Html.program instead. I replaced Html.App with Html.program but the module is not importing.
When I run elm-make I get a syntax problem saying it's looking for an upper case name? Screen shot of my Main.elm and error below.
Main.elm
Error message
You don't import Html.program, only Html.
import Html
Then you use it by referencing as you already have,
main = Html.program {...}
-- or...
main = Html.beginnerProgram {...}
There is no "Program" module. It's in Html itself.
Just do import Html and then you can use Html.program
Related
I have two javaScript pages.
and i used apexCharts on the first page, and on this page i exported a variable to use in the second page.but when i import the variable, it gives an error that appexCharts is not defind! . while I didn't export the apexCharts at all, which gives this error.it looks like appexCharts is exporting the entire first page
Is there a way to get intellisense to work for imported mutation types with Vue and VS Code. I have the Vetur extension installed and I am using constant named mutations.
I want to have a file - mutation-types.js
export default {
MY_MUTATION_TYPE: 'MY_MUTATION_TYPE',
ANOTHER_MUTATION_TYPE: 'ANOTHER_MUTATION_TYPE'
}
then whenever I import:
import mutationTypes from './mutation-types'
I want to have intelisense on the mutationTypes object.
Is this is anyway possible?
Isn't this wrong and throwing syntax errors?
It should be:
export default {
MY_MUTATION_TYPE: 'MY_MUTATION_TYPE',
ANOTHER_MUTATION_TYPE: 'ANOTHER_MUTATION_TYPE',
}
That would make auto complete work.
Since you are doing default export, in your import you also should use default import syntax. In your case mutationTypes can be any name, so that's why autocomplete will not work in the import. It will work on the object itself though:
To make it work in imports, you should use named exports.
There are 2 projects generated by vue-cli.
one of it I could add component like this code below:
Vue.component('HeaderBar',require("./components/common/HeaderBar.vue"));
But another one I can't do this , I must code like this:
Vue.component('HeaderBar',require("./components/common/HeaderBar.vue").default);
if not, I will get this error message:
Failed to mount component: template or render function not defined
Is anyone could tell me Why like this ？
Thank you for help .
When using ES6 imports (export default HeaderBar), the exported module is of the format {"default" : HeaderBar}. The import statement handles this assignment for you, however, you have to do the require("./mycomponent").default conversion yourself. The HMR interface code cannot use import as it doesn't work inline.
If you want to avoid that, use module.exports instead of export default.
I'd like to separate the View and Update parts of a program into separate source files, but then, how do I share the Message and Subscriptions declarations ?
Think twice before splitting your modules, premature code splitting might be harmful to your project.
Here is an example of the project structure I use in my Elm apps.
Messages
Html.App.map allows us to tag a message for child component, so we could pass it to Components.Counter.Update.update function, when keyboard subscription emits a message.
module App.View exposing (..)
import Html.App
import Html exposing (text, div, Html)
import App.Model exposing (Model)
import App.Messages exposing (..)
import Components.Counter.View
view : Model -> Html Msg
view model =
div []
[ Html.App.map Counter (Components.Counter.View.view model.counter) ]
Subscriptions
To tag a message from a subscription, we have to use Platform.Sub.map
Please see an example of subscription passing in src/App/Subscriptions.elm
module App.Subscriptions exposing (..)
import App.Model exposing (Model)
import App.Messages exposing (..)
import Components.Counter.Subscriptions
subscriptions : Model -> Sub Msg
subscriptions model =
let
counterSub =
Components.Counter.Subscriptions.subscriptions model.counter
in
Sub.batch [ Sub.map Counter counterSub ]
File structure
Main.elm -- Entry point, where App is initialized
Utils.elm -- Utilities
App/
Messages.elm
Model.elm
Subscriptions.elm
Update.elm
View.elm
Components/
StatefulComponent/
Messages.elm
Model.elm
Subscriptions.elm
Update.elm
View.elm
StatefulComponentWithCommands/
Commands.elm -- Functions, which return Cmd msg
Messages.elm
Model.elm
Subscriptions.elm
Update.elm
View.elm
StatelessComponent/
View.elm
An Elm program can be progressively split into several files as follows :
extract message declarations and associated types into Messages.elm
Add import Messages exposing (..) in Main.elm.
Compile it and test.
extract model declaration and initialisation into Models.elm.
Add import Messages exposing (..) in Models.elm.
Add import Models exposing (..) in Main.elm
Compile it and test
extract the view function into View.elm.
Add import Messages exposing (..) in View.elm.
Add import Models exposing (..) in View.elm
Add import View exposing (..) in Main.elm
Compile it and test
A the end, Main.elm still has the subscriptions and update parts. They can be extracted similarly.
See example at github.com/sporto/elm-tutorial-app/tree/master/src, with corresponding tutorial at elm-tutorial.org/en/05-resources/01-intro.html.
With Java, import is really easy and clear.
You import with the following statement :
import fr.domain.MyUtils;
Then you can use it like this:
MyUtils.myStaticMethod();
You need to namespace MyUtils only if there are two in the same file.
With Typescript AMD and requirejs it seems to be more complicated.
Here the import statement:
import u = require('fr/domain/MyUtils');
And the way to use it:
u.fr.domain.MyUtils.myStaticMethod();
Quite verbose...
The only way I found so fare to use an alias was to double the import statement:
import u = require('fr/domain/MyUtils');
import MyUtils = u.fr.domain.MyUtils;
After doing that you can write this in a module:
MyUtils.myStaticMethod();
It's cleaner but Eclipse TS plugin get completely lost with this and auto completion become erratic. In Visual Studio auto completion is OK but "F12 Go to definition" has to be done twice which is annoying.
Is there a better way to do this ? Or should we just keep namespaces as short as we can ?
You’re doing it wrong.
Your 'fr/domain/MyUtils' module should be exporting only whatever is supposed to be MyUtils. i.e. it should look like this:
export function myStaticMethod() { /* ...code... */ }
It should not be exporting some global namespace object, and it should not be adding anything to some global namespace object that you get from somewhere else. The natural placement of module files in directories is the way you create “namespaces” when you work with external modules.
If you do it correctly then your consumer looks like this:
import MyUtils = require('fr/domain/MyUtils');
MyUtils.myStaticMethod();
or, even more properly using ES module syntax:
import { myStaticMethod } from 'fr/domain/MyUtils';
myStaticMethod();