scalameta/scalafmt

Code formatter for Scala

Raitis Veinbahs

@siers

I was planning to try running Scalafmt.format and see how the tree that it is getting looks like by printing it, but I absolutely cannot get anything to work...

Raitis Veinbahs

@siers

I was running it with cli/run

Maxime Kjaer

@MaximeKjaer

Hey all,

I've opened a PR to add scalafmt to Scala.js: scala-js/scala-js#4260. However, I think I may have encountered a bug when reformatting the codebase, whereby a file's contents got deleted as a result of the reformat. I have a hunch of what may have happened, but I'm not quite certain about it, so I wanted to ask here if this makes any sense.

I added a top-level script (in this commit https://github.com/scala-js/scala-js/pull/4260/commits/95dbd1fc548d6c8737f71b8e855661fe7d57e4cb) that executes scalafmt for each subproject, on multiple threads. However, when I ran the top-level scalafmtAll, the contents of a file got deleted, which is unexpected. Now, Scala.js has many subprojects, many of which have overlapping file sets. My thinking is that two separate scalafmt threads may have overwritten each other's results. Is this possible at all? If so, would it be possible to change the implementation so that scalafmt always gets a lock on a file before writing it? Or should I not be using scalafmt as a top-level script like that in the first place?

3 replies

Mykhailo Osypov

@mosyp

Hi, how am I able to format code like this:

def func(a: Int)
                  (implicit b: Int): Int = ???

because the default one is:

def func(a: Int)(implicit 
    b: Int
): Int = ???

I've tried to use optIn.configStyleArguments = false but didn't worked for me.
Or, is there any possible way to turn off function definition formatting?

1 reply

Sean Romocki

@sromocki

Hello all,
I'm trying to use the Scala plugin (updated to latest version) in IntelliJ 2020.2.3 which comes with scalafmt and I'm seeing the below error.

12:02 PM    Can not resolve scalafmt version 2.6.2:
                 An error occurred during downloading:
                 unresolved dependency: org.scalameta#scalafmt-cli_2.12;2.6.2: not found
                     unresolved dependency: org.scala-lang#scala-reflect;2.12.8: not found

At one point I had the old deprecated Scalafmt plugin installed but I have uninstalled it (not sure if some lingering caching related to that plugin is what's causing this issue)

I get this error no matter what version of scalafmt I change it to

Pathikrit Bhowmick

@pathikrit

Is scalafmt the right tool to also format resources? Use case: we check in .csv files under src/test/resources which contain test cases. We would like to keep this CSV files sorted.

Georgi Krastev

@joroKr21

Hi, sorry if this has been asked before but it's really hard to search for. Is there a way to configure select chains like this:

1.to(5).map { x =>
  val y =  x + 1
  y * y
}.filter(_ % 2 == 0)

as opposed to:

1.to(5).map { x =>
  val y =  x + 1
  y * y
}
.filter(_ % 2 == 0)

I really dislike the dangling code after a closing curly brace but I couldn't find a way to configure it the way I want

2 replies

rnd4222

@rnd4222_gitlab

Would be cool to be able to disable all formatting and then selectively opt-in for some rules

James Yoo

@jamesyoo_gitlab

Hi folks! Is there a scalafmt setting for enforcing parens around one arg lambdas? e.g.

xs.map { x: T =>
    foo(x)                 // should fail to lint
}

and instead get

xs.map { (x: T) =>
    foo(x)                 // fine
}

I've looked in the docs and issues on GitHub and couldn't find a discussion on this. This is for prepping a codebase to migrate to Scala 3

Matt Hicks

@darkfrog26

is there any way to make Scalafmt remove aligned types? Like:

class Foo(
  one:     Bar,
  another: Baz
)

so that it formats:

class Foo(
  one: Bar,
  another: Baz
)

after running formatting it seems to retain that

Eric K Richardson

@ekrich

Align=more or most are the settings - not sure if that is what you are asking.

Matt Hicks

@darkfrog26

I set alignment:

align = none
align.openParenCallSite = true
align.openParenDefnSite = true
align.stripMargin = true

1 reply

it doesn't appear to remove the spaces in formatting

I want an aggressive reformatting, but scalafmt seems pretty passive

Matt Hicks

@darkfrog26

Ah, nevermind. It was because I wasn't setting the version on Scalafmt, so IntelliJ was formatting with version 1.5.1 by default.

Explicitly setting the version to 2.7.5 fixed it

Matt Hicks

@darkfrog26

is there any way to get:

def foo(
  one: Int,
  two: Int
)

to be formatted as:

def foo(one: Int,
        two: Int)

Eric K Richardson

@ekrich

Let me look scala native uses that one

I think it is in these.

# changed 1.6 or after
align.openParenCallSite = true
align.openParenDefnSite = true
# avoid wrapping parens on new line
danglingParentheses.defnSite = false
danglingParentheses.callSite = false

Sean Romocki

@sromocki

I'm still not able to use scalafmt in IntelliJ and I'm not sure what else to try to get it to work. Seeing

11:34 AM    Can not resolve scalafmt version 2.7.5:
                    An error occurred during downloading:
                    unresolved dependency: org.scalameta#scalafmt-cli_2.12;2.7.5: not found
                    unresolved dependency: org.scala-lang#scala-reflect;2.12.8: not found

6 replies

@theqp

instead of this

  def foo =
    1
      .tap { s =>
        s.toString
      } tap { s =>
      s.toString
    }

I want

  def foo =
    1
      .tap { s =>
        s.toString
      } tap { s =>
        s.toString
      }

4 replies

what should I change in the config?

@theqp

I have found a solution: not mixing infix and dot notation

  def foo2 =
    1 tap { s =>
      s.toString
    } tap { s =>
      s.toString
    }

Philipp Dörfler

@phdoerfler

Hi! I want to use scalafmt on code I generated. My program is currently running on scastie, so I can't have a configuration file. Is there an alternative to scalafmt.format that I can call without a path to a config file? Where can I find the API docs? Thanks!

4 replies

Jason Pickens

@steinybot

Can someone please explain how newlines.topLevelStatementsMinBreaks works? I don’t really understand it. I think I get what the docs say but it doesn’t seem to work how I expect so my interpretation must be wrong. I tried:

newlines {
  topLevelStatements = [before]
  topLevelStatementsMinBreaks = 1
}

And expected a newline before every top level statement but it doesn’t do that. What I actually want is a newline before and after every top level def but I don’t know how to do that.

4 replies

Eric K Richardson

@ekrich

For the most part scalafmt doesn't mess with your blank lines. Those tend to be easy to change and review easily. What are you trying to achieve?

Jason Pickens

@steinybot

I want it to insert new lines before top level defs

Eric K Richardson

@ekrich

I don't see any rewrite rules for that sort of thing.

Jason Pickens

@steinybot

The example for https://scalameta.org/scalafmt/docs/configuration.html#newlinestoplevelstatementsminbreaks seems to be doing something similar

That’s with:

newlines.topLevelStatements = [before,after]
newlines.topLevelStatementsMinBreaks = 0

It does it for all top level statements though which is worse. I’ll just put them in manually, it’s not too bad.

Eric K Richardson

@ekrich

Sorry, I haven't used it before - it seems a bit strange to me too when clicking on before/after.

rc4m

@rc4m

Hi! Is there a way to align the = with the <- in for comprehensions? align.preset=more seems to only align <- with <- and = with =.

rc4m

@rc4m

Found my answer on Discord.

@theqp

hi
scalafmt currently formats like this

    x match {
      case (
            "xxxxxxxxxxxxxxxxxxxxxx" | "xxxxxxxxxxxxxxx" | "xxxxxxxxxxxxxxx" |
            "xxxxxxxxxxxxxxx" | "xxxxxxxxxxxxx"
          ) =>
        y
    }

i want it to look like this

  def loadRow3(): Unit =
    x match {
      case (
            "xxxxxxxxxxxxxxxxxxxxxx"
              | "xxxxxxxxxxxxxxx"
              | "xxxxxxxxxxxxxxx"
              | "xxxxxxxxxxxxxxx"
              | "xxxxxxxxxxxxx"
          ) =>
        y
    }

dieselmat

@dieselmat

hello, I've looked into the documentation and configuration a few times. But fail to see where I could disable the code formatting temporarily via sbt of the scalafmt.conf file. All I fount was // format: off. I'd like to temporarily disable formatting for a quick dev build. Anyone can point out a config for it?

Anton Sviridov

@keynmol

something like https://scalameta.org/scalafmt/docs/installation.html#format-on-compile ?

unless this is turned on in your build, scalafmt shouldn't just reformat the code unprompted

dieselmat

@dieselmat

Thanks! Will try

Artem Nikiforov

@nikiforo

Hi,
By default(I suppose) scalafmt changes this

seqTuple2
  .map { case (a1, a2) =>
    ???
  }

to this

seqTuple2
  .map {
    case (a1, a2) =>
      ???
  }

I've tried to find the way how to turn this feature off couple of times, but with no results.
I've found term case arrows, but not sure if this is what I'm searching.
Can I disable this rewrite rule?

@theqp

i think this is not related to case, but to blocks

Johan Grande

@nahoj

Hi all,
I'm trying to make scalafmt format consecutive parameter blocks (at defn site) in the same way, i.e. to avoid formatting such as:

class MyClass(aaaaaaa: Aaaaaaaaa,
              bbbbbbbbbbbbb: Bbbbbbbbbbbbbbb)
             (implicit ccccccc: Ccccccccc,
              dddddddddddd: Dddddddddddd) extends Eeeeeeee {}

class MyClass(aaaaaaa: Aaaaaaaaa, bbbbbbbbbbbbb: Bbbbbbbbbbbbbbb)(implicit
    ccccccc: Ccccccccc,
    dddddddddddd: Dddddddddddd)
    extends Eeeeeeee {}

here with

align.openParenDefnSite = true
danglingParentheses.defnSite = false

Is this at all possible?

Thai Dang Vu

@dxxvi

Hi All, this is a very basic configuration but I don't know how to do it

object Main extends App {
  println("hello")
  println("world")
}

What should I use in .scalafmt.conf so that there are 4 spaces before the println?

Eric K Richardson

@ekrich

In general, standard Scala formatting uses 2 space indention unlike Java. https://docs.scala-lang.org/style/indentation.html Here are the scalafmt docs: https://scalameta.org/scalafmt/docs/configuration.html You can search for indentation.

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