bkirwi/decline

---

bkirwi/decline.json

{
  "createdAt": "2016-10-23T00:30:19Z",
  "defaultBranch": "main",
  "description": "A composable command-line parser for Scala.",
  "fullName": "bkirwi/decline",
  "homepage": "http://monovore.com/decline/",
  "language": "Scala",
  "name": "decline",
  "pushedAt": "2025-11-09T22:52:36Z",
  "stargazersCount": 668,
  "topics": [],
  "updatedAt": "2025-11-14T13:59:45Z",
  "url": "https://github.com/bkirwi/decline"
}

decline

A composable command-line parser, inspired by [optparse-applicative][optparse] and built on [cats][cats].

import cats.syntax.all._
import com.monovore.decline._

object HelloWorld extends CommandApp(
  name = "hello-world",
  header = "Says hello!",
  main = {
    val userOpt =
      Opts.option[String]!("target", help = "Person to greet.")
        .withDefault("world")

    val quietOpt = Opts.flag("quiet", help = "Whether to be quiet.").orFalse

    (userOpt, quietOpt).mapN { (user, quiet) =>

      if (quiet) println("...")
      else println(s"Hello $user!")
    }
  }
)

To get started, please visit monovore.com/decline!

About the Project

decline is a Typelevel project, and follows the Typelevel Scala Code of Conduct.

This project is released under the Apache License 2.0.

[optparse] !: https://github.com/pcapriotti/optparse-applicative [cats] !: https://github.com/typelevel/cats [decline] !: http://ben.kirw.in/decline/