scalameta/scalameta

Library to read, analyze, transform and generate Scala programs

Ólafur Páll Geirsson

@olafurpg

@ghik you might want to try using the latest SNAPSHOT

otherwise, I don't import the scalameta build into metals since it conflicts with the SemanticDB plugin (which is developed in the scalameta build and Metals uses it)

we do funky stuff like customize the sourceroot setting to be a subdirectory, which doesn't play nicely with Metals

Jiuyang Liu

@sequencer

Hello, I wonder how to implement a "find usage" Scala? since after AST generation, there won't be any packages information for codes. Is there any compiler plugin to help me with this?

Ólafur Páll Geirsson

@olafurpg

@ghik I was able to get Metals working in the Scalameta build using the latest Metals SNAPSHOT

Ólafur Páll Geirsson

@olafurpg

@sequencer you can use the SemanticDB compiler plugin to emit protobuf data with symbol references

you'll need a bit more work to handle references to overridden methods

You can poke into the Metals codebase to see how "textDocument/references" is implemented

Jiuyang Liu

@sequencer

OK! Thank you! I'll try.

Roman Janusz

@ghik

@olafurpg thanks, will try it out

Ólafur Páll Geirsson

@olafurpg

We’re hopefully doing a stable release in a couple days if you can hold out the wait

Roman Janusz

@ghik

@olafurpg I still can't make it work with current snapshot. I built 0.7.7-SNAPSHOT from today's master and I'm getting this:

java.util.concurrent.ExecutionException: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: DecodingFailure(Attempt to decode value on failed cursor, List(DownField(providesFileWatching), DownField(capabilities)))
    at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
    at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1915)
    at scala.meta.internal.metals.BuildServerConnection$.initialize(BuildServerConnection.scala:176)
    at scala.meta.internal.metals.BuildServerConnection$.fromStreams(BuildServerConnection.scala:129)
    at scala.meta.internal.metals.BloopServers.$anonfun$newServer$1(BloopServers.scala:71)
    at scala.util.Success.$anonfun$map$1(Try.scala:255)
    at scala.util.Success.map(Try.scala:213)
    at scala.concurrent.Future.$anonfun$map$1(Future.scala:292)
    at scala.concurrent.impl.Promise.liftedTree1$1(Promise.scala:33)
    at scala.concurrent.impl.Promise.$anonfun$transform$1(Promise.scala:33)
    at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:64)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: DecodingFailure(Attempt to decode value on failed cursor, List(DownField(providesFileWatching), DownField(capabilities)))
    at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.handleResponse(RemoteEndpoint.java:209)
    at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.consume(RemoteEndpoint.java:193)
    at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.handleMessage(StreamMessageProducer.java:194)
    at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.listen(StreamMessageProducer.java:94)
    at org.eclipse.lsp4j.jsonrpc.json.ConcurrentMessageProcessor.run(ConcurrentMessageProcessor.java:113)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

Ólafur Páll Geirsson

@olafurpg

@ghik you may have an old version of bloop running

our CI publishes a SNAPSHOT on every merge BTW http://scalameta.org/metals/docs/editors/vscode.html#using-latest-metals-snapshot

we're waiting for a stable release of bloop to come out before releasing metals v0.8

maybe best to wait until then

Roman Janusz

@ghik

ok, thanks, that's probably what I will do

but I don't understand why I'm running wrong version of bloop - isn't it set up automatically by metals?

Tomasz Godzik

@tgodzik

@ghik might also be needed to reimport the build - that message usually means that some json has an unexpected structure

Jakub Kozłowski

@kubukoz

I'm having trouble running scalafifx on a project (RemoveUnused) - using the sbt plugin/task. The plugin claims the files were changed but they remain unmodified...

sbt:OrderService> scalafix RemoveUnused
[info] Running scalafix on 10 Scala sources
[info] Running scalafix on 6 Scala sources
[info] Running scalafix on 3 Scala sources
[info] Running scalafix on 50 Scala sources
[success] Total time: 1 s, completed Dec 17, 2019 12:35:41 PM

yet nothing changes

I have the necessary flags on, and can see warnings on a fresh compile

would appreciate any hints

sandeshyapuram

@pandareen

Hello, can you point me to some examples? I could use some full-blown tutorials

Bartosz Bąbol

@BBartosz

According to main page of scalameta: Scalameta- Library to read, analyze, transform and generate Scala programs -> how exactly scalameta is used to generate scala programs since macros are not part of scalameta anymore?

Gabriele Petronella

@gabro

@BBartosz you can generate programs by constructing trees and printing them with Scalameta. Macros allow you to do roughly the same thing, except you do it during the compilation of your program

in other words, you can do code generation with Scalameta

(I use it for this purpose at work)

Ólafur Páll Geirsson

@olafurpg

@BBartosz Scalameta does not support macros, you can use scala-reflect macros instead

Roman Janusz

@ghik

Hi!
I have an already parsed Source. I also have a Position representing some arbitrary range in that source. I would like to obtain Tokens representing tokens only from that range. How can I do this efficiently?

Is there anything better I can do than manually implementing binary search?

Ólafur Páll Geirsson

@olafurpg

You can access the underlying token array by using a package private API called “Origin”

But you would still need to know the index in the array where your range starts

So binary search is the best solution if you already have the token array.

Roman Janusz

@ghik

Thanks

Bartosz Bąbol

@BBartosz

@BBartosz you can generate programs by constructing trees and printing them with Scalameta. Macros allow you to do roughly the same thing, except you do it during the compilation of your program

How exactly you generate them? I understand that you use quasiquotes to build your tree and then you save it to file, kinda like string?

Roman Janusz

@ghik

@BBartosz yes, this way. You cannot generate programs with scalameta "on the fly", that is in compile time like macros.

Bartosz Bąbol

@BBartosz

@BBartosz yes, this way. You cannot generate programs with scalameta "on the fly", that is in compile time like macros.

yeah thx i was wondering whats the way to do it. I was using quasiquotes and macros but generating the code and saving it to file might also work for me

sandeshyapuram

@pandareen

Is there a better way to kick off code generation? I am using Scala Annotations for pointing it towards scalameta to generate new codee.

Ólafur Páll Geirsson

@olafurpg

@pandareen if you are generating source code as strings, I would recommend using something like treehugger instead http://eed3si9n.com/treehugger/

vito-c

@vito-c

@olafurpg would treehugger be something we could use for refactoring as well? right now I am using patch like this:

        Patch.replaceTree(
          someTree,
          "val foo:SomeType = new Thing(1, 2,3)"
        )

Charlie Hills

@contagnas

Hi all, wondering if someone could clarify the behavior of the semanticdb-scalac plugin for me. I'm running this command:

$ ~/Downloads/scala-2.13.1/bin/scalac -Xplugin:$(realpath ~/Downloads/semanticdb-scalac_2.13.1-4.3.0.jar) -Yrangepos -Xplugin-require:semanticdb HelloWorld.scala

I'm expecting to see semanticdb files in META-INF/semanticdb, but I do not. In fact, if I create the META-INF/semanticdb directory before running the above command, the semanticdb directory is deleted.

Ondra Pelech

@sideeffffect

Hello, is there an integration between ScalaMeta/SemanticDB and Kythe?

Muhammad Tabaza

@Tabzz98

Hi guys!
Is there a way pass a Source to scala.tools.reflect.ToolBox.eval()?

sandeshyapuram

@pandareen

Hello guys, what is the latest method to design frameworks that overcome Type Erasures? Does scalameta aim to solve this?

I wouldn't want to use scala reflection as it's experimental

Ólafur Páll Geirsson

@olafurpg

@contagnas it looks like you need the targetroot option as well

❯ cs launch scala:2.13.1 -- -Xplugin:$(cs fetch --intransitive org.scalameta:semanticdb-scalac_2.13.1:4.3.7) -Yrangepos -Xplugin-require:semanticdb -P:semanticdb:targetroot:$(pwd) foo.scala
❯ tree
.
├── foo.scala
└── META-INF
   └── semanticdb
      └── foo.scala.semanticdb

where cs is coursier from https://get-coursier.io/docs/cli-overview

@sideeffffect there's no published integration with kythe, i recall somebody implemented something a couple years ago but it didn't end up going anywhere I think

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