scalaunfmt generates the .scalafmt.conf that have minimum change to existing scala codebase on running scalafmt. The candidate fields and values for resulting .scalafmt.conf can be controlled using configuration for scalaunfmt.

coursier bootstrap com.github.tanishiking:scalaunfmt_2.12:0.0.5 \
  -r sonatype:releases \
  -o scalaunfmt --standalone --main com.github.tanishiking.scalaunfmt.cli.Cli

Usage: scalaunfmt [options] [<file>...]

  <file>...              file or directory, in which case all *.scala files are formatted.
  -c, --config <value>   a file path to .scalaunfmt.conf (default: .scalaunfmt.conf).
  -v, --version <value>  running version of scalafmt
  -o, --output <value>   output file path (by default, scalaunfmt will write the result to stdout).

We can use any versions of scalafmt using -v option (scalaunfmt will download the jar for specified version of scalafmt using scalafmt-dynamic).

The configuration for scalaunfmt looks like that for scalafmt, the difference is that the configuration for scalaunfmt requires the list of values on the right-hand side (instead of specific value). scalaunfmt will generate the multiple configurations for scalafmt using the combinations of rhs of scalaunfmt conf.

For example,

maxColumn = [80, 100]
align = [none, some]

scalaunfmt will generate the following list of scalafmt conf from the above one, and choose the best one that minimize the change to existing scala codebase.

maxColumn = 80
align = none

maxColumn = 80
align = some

maxColumn = 100
align = none

maxColumn = 100
align = more

For the available list of fields and values for .scalafmt.conf, refer https://scalameta.org/scalafmt/docs/configuration.html

continuationIndent.callSite = [2, 4]
continuationIndent.defnSite = [2, 4]

rewrite.rules = [
  [
    AvoidInfix
    RedundantBraces
  ]
  [
    AvoidInfix
  ]
]