Optional - Githubissues

mb720 commented 8 years ago

Hi and thanks a lot for JSweet!

I'd like to use java.util.Optional or something equivalent in my Java code and transpile it to JavaScript.

When I import java.util.Optional I get this error:

cannot find name 'java' at path/to/src/MyClass.java(4)
cannot find namespace 'java' at path/to/src/MyClass.java(4)

Is there a way to use Optional and have JSweet transpile it?

For context, this is from my build.gradle:

compile group: 'org.jsweet', name: 'jsweet-transpiler', version: "1.1.0"
compile group: 'org.jsweet.candies', name: 'jsweet-core', version: "1.1.0-20160525"

jsweet {
  targetVersion = org.jsweet.transpiler.EcmaScriptComplianceLevel.ES5
  ...
}

renaudpawlak commented 8 years ago

It is possible to use java.util.Optional (and any other JDK object) under the condition that you provide a JSweet implementation of it in the j4ts project. Currently j4ts supports basic collections of java.util but it would be quite simple to add support for Optional. I encourage everybody to contribute to that project whenever they need a Java API in JSweet.

lgrignon commented 8 years ago

This could be a nice feature indeed! In addition, it should be fairly simple to implement Optional into j4ts. @mb720, let me know if you PR it, I will give it a try. Thanks.

mb720 commented 8 years ago

Thanks for your quick answers!

I'm trying to figure out how to provide a JSweet implementation for Optional.

In j4ts/target/ts/bundle.ts starting at line 964 I can see that OptionalDouble has a TypeScript implementation. Does that mean that I can transpile OptionalDouble with JSweet 1.1.1?

Because when I try to use OptionalDouble in my current setup with the JSweet transpiler 1.1.0 I can't: cannot find name 'java' ...

renaudpawlak commented 8 years ago

I should have checked. Optional is indeed already supported by j4ts: https://github.com/cincheo/j4ts/blob/master/src/main/java/java/util/Optional.java. So the only logical explanation is a problem in the j4ts candy or that you don't have the j4ts candy (or not the right version) in your dependencies. Check your pom.xml.

        <dependency>
            <groupId>org.jsweet.candies</groupId>
            <artifactId>j4ts</artifactId>
            <version>0.1.0</version>
        </dependency>

You can also try the 0.2.0-SNAPSHOT.

Can you check this out?

mb720 commented 8 years ago

That looks promising! Indeed, I hadn't included the j4ts candy in my dependencies.

When I do so by adding

compile group: "org.jsweet.candies", name: "j4ts", version: "0.1.0"

to my build.gradle, JSweet generates a bundle.js that includes code for java.util.Optional in .jsweet\candies\js\j4ts-0.1.0 at the root of my project.

How do I change the directory where this bundle.js is generated so I can source it inside my HTML? I assumed that this part of the JSweet config in build.gradle would accomplish that:

jsweet {
  outDir = new File('src/main/resources/public/js')
  // ...
}

Thanks again for your help so far!

renaudpawlak commented 8 years ago

I think you need to use the candiesJsOut option (see the doc).

mb720 commented 8 years ago

Oh thanks, I forgot about candiesJsOut. It did the trick.

So, in summary, to use java.util.Optional with JSweet, I had to add

compile group: "org.jsweet.candies", name: "j4ts", version: "0.1.0"

and

jsweet {
  // Your path may vary
  def jsDir = new File('src/main/resources/public/js')
  outDir = jsDir
  candiesJsOut = jsDir
  // ...
}

to my build.gradle.

In my HTML I have this:

<body>
  // Order of scripts is important since the second script depends on the first
  <script src="/js/j4ts-0.1.0/bundle.js"></script>
  <script src="/js/FileThatUsesOptional.js"></script>
</body>

Thanks again for your help!

cincheo / jsweet

Optional #139