scalameta/scalameta

Library to read, analyze, transform and generate Scala programs

Ólafur Páll Geirsson

@olafurpg

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

@Tabzz98 Source.toString gives you the code that you can feed to eval

@pandareen scalameta does not provide any features for runtime reflection. The only alternatives I'm aware of are scala/java runtime reflection

Muhammad Tabaza

@Tabzz98

@olafurpg Ah, of course. I don't know why I didn't consider a solution where the parsing is done twice. All I had in mind was converting the whole tree. Thanks a lot!

Ondra Pelech

@sideeffffect

@olafurpg thanks for the info

Dale Wijnand

@dwijnand

Am I right in saying that there's information missing in the following, to link an eta-expansion to the method it expands?

trait NullaryEtaExpansionScala[A] {
  def prop: A
  def meth(): A

  def def_prop = prop _
  def def_meth = meth _
}

$ type metac
metac is aliased to `coursier launch org.scalameta:metac_2.12.11:4.3.7 -- -cp /Users/dnw/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.12.11/scala-library-2.12.11.jar'

$ type metap
metap is aliased to `coursier launch -M scala.meta.cli.Metap org.scalameta:scalameta_2.12:4.3.7 --'

$ metac -P:semanticdb:synthetics:on NullaryEtaExpansionScala.scala

$ tree META-INF/
META-INF/
└── semanticdb
    └── NullaryEtaExpansionScala.scala.semanticdb

1 directory, 1 file

$ metap .
NullaryEtaExpansionScala.scala
------------------------------

Summary:
Schema => SemanticDB v4
Uri => NullaryEtaExpansionScala.scala
Text => empty
Language => Scala
Symbols => 6 entries
Occurrences => 10 entries

Symbols:
_empty_/NullaryEtaExpansionScala# => trait NullaryEtaExpansionScala[A] extends AnyRef { +4 decls }
_empty_/NullaryEtaExpansionScala#[A] => typeparam A
_empty_/NullaryEtaExpansionScala#def_meth(). => method def_meth: Function0[A]
_empty_/NullaryEtaExpansionScala#def_prop(). => method def_prop: Function0[A]
_empty_/NullaryEtaExpansionScala#meth(). => abstract method meth(): A
_empty_/NullaryEtaExpansionScala#prop(). => abstract method prop: A

Occurrences:
[0:6..0:30) <= _empty_/NullaryEtaExpansionScala#
[0:31..0:32) <= _empty_/NullaryEtaExpansionScala#[A]
[1:6..1:10) <= _empty_/NullaryEtaExpansionScala#prop().
[1:12..1:13) => _empty_/NullaryEtaExpansionScala#[A]
[2:6..2:10) <= _empty_/NullaryEtaExpansionScala#meth().
[2:14..2:15) => _empty_/NullaryEtaExpansionScala#[A]
[4:6..4:14) <= _empty_/NullaryEtaExpansionScala#def_prop().
[4:17..4:21) => local0
[5:6..5:14) <= _empty_/NullaryEtaExpansionScala#def_meth().
[5:17..5:21) => local1
$

There's no reference occurrence of prop(). and no link from symbol local0, right?

Damien Favre

@benderpremier

Hi :wave: , I am wondering if it's possible to generate type parameters that are literal type.
I am trying to do

Type.Apply(Type.Name("Bytes"), List(Type.Name("32")))

but when calling .syntax I am getting

Bytes[`32`] 
\\instead of 
Bytes[32]

Ólafur Páll Geirsson

@olafurpg

@benderpremier what happens if you use Lit.Int(32)?

Dale Wijnand

@dwijnand

$ m Foo.java
package pkg;

interface Foo {
  String foo();
}

$ m scratch.scala
package pkg

class CM extends Foo { def foo() = "" }
class CP extends Foo { def foo   = "" }

$ l
.
├── [  48]  Foo.java
└── [  93]  scratch.scala

0 directories, 2 files

$ metac Foo.java scratch.scala

$ metap .
scratch.scala
-------------

Summary:
Schema => SemanticDB v4
Uri => scratch.scala
Text => empty
Language => Scala
Symbols => 6 entries
Occurrences => 11 entries

Symbols:
pkg/CM# => class CM extends Object with Foo { +2 decls }
pkg/CM#`<init>`(). => primary ctor <init>()
pkg/CM#foo(). => method foo(): String
pkg/CP# => class CP extends Object with Foo { +2 decls }
pkg/CP#`<init>`(). => primary ctor <init>()
pkg/CP#foo(). => method foo(): String

Occurrences:
[0:8..0:11) <= pkg/
[2:6..2:8) <= pkg/CM#
[2:9..2:9) <= pkg/CM#`<init>`().
[2:17..2:20) => pkg/Foo#
[2:21..2:21) => java/lang/Object#`<init>`().
[2:27..2:30) <= pkg/CM#foo().
[3:6..3:8) <= pkg/CP#
[3:9..3:9) <= pkg/CP#`<init>`().
[3:17..3:20) => pkg/Foo#
[3:21..3:21) => java/lang/Object#`<init>`().
[3:27..3:30) <= pkg/CP#foo().

Is there no information in the Semanticdb that that the foo method in CM and CP is implementing/overridingFoo#foo().?

Even in the all-Scala, 1-file version:

$ m scratch.scala
package pkg

trait Foo { def foo(): String }

class CM extends Foo { def foo() = "" }
class CP extends Foo { def foo   = "" }

$ metap .
scratch.scala
-------------

Summary:
Schema => SemanticDB v4
Uri => scratch.scala
Text => empty
Language => Scala
Symbols => 8 entries
Occurrences => 14 entries

Symbols:
pkg/CM# => class CM extends AnyRef with Foo { +2 decls }
pkg/CM#`<init>`(). => primary ctor <init>()
pkg/CM#foo(). => method foo(): String
pkg/CP# => class CP extends AnyRef with Foo { +2 decls }
pkg/CP#`<init>`(). => primary ctor <init>()
pkg/CP#foo(). => method foo(): String
pkg/Foo# => trait Foo extends AnyRef { +1 decls }
pkg/Foo#foo(). => abstract method foo(): String

Occurrences:
[0:8..0:11) <= pkg/
[2:6..2:9) <= pkg/Foo#
[2:16..2:19) <= pkg/Foo#foo().
[2:23..2:29) => scala/Predef.String#
[4:6..4:8) <= pkg/CM#
[4:9..4:9) <= pkg/CM#`<init>`().
[4:17..4:20) => pkg/Foo#
[4:21..4:21) => java/lang/Object#`<init>`().
[4:27..4:30) <= pkg/CM#foo().
[5:6..5:8) <= pkg/CP#
[5:9..5:9) <= pkg/CP#`<init>`().
[5:17..5:20) => pkg/Foo#
[5:21..5:21) => java/lang/Object#`<init>`().
[5:27..5:30) <= pkg/CP#foo().

I'm assuming metap outputs all the information available.

Is it up to the client to traverse [4:17..4:20) => pkg/Foo# to determine if the method is implementing/overriding??

Dale Wijnand

@dwijnand

I say "traverse [4:17..4:20) => pkg/Foo#" but I mean that using the existing scalameta/scalafix infrastructure, is the logic client-side?

Damien Favre

@benderpremier

@olafurpg if I use Type.Apply(Type.Name("Bytes"), List(Lit.Int(32))) I get that exception

Exception in thread "main" org.scalameta.invariants.InvariantFailedException: invariant failed:
when verifying og.categories.intersect[String](ig.categories).nonEmpty
found that og.categories.intersect[String](ig.categories).nonEmpty is false
where ig = Literal
where og = Typ

Ólafur Páll Geirsson

@olafurpg

@dwijnand SemanticDB doesn't include override information at the moment

Where communities thrive

People

Repo info

Activity