shapeless-commandline is a Scala library which takes advantage of Miles Sabin's shapeless library as well as Scalaz to perform typesafe and functional command line argument parsing. This work was heavily inspired by the Scallop library by Rogach.
This library supports many (but not all) of the features provided by scallop. Here is a menu of what is included:
- POSIX-style short option names (-x -y -z 42) with grouping (-xyz42, -xyz 42)
- GNU-style long option names (--send-more-chuck-berry)
- Key-value arguments (-Dkey1=value1 -D key2=value2)
- Simple support for custom command line parsers using the enrich-my-library pattern
- Similar trailing arguments matching provided by scallop (but here be dragons...only use it if ambiguous parsing can't cause problems)
- Subcommands
- Post-parse argument validation
The shapeless-commandline library is hot off the press, and there are a lot of rough edges. Ouch, it's so hot!
This library is one part in a trilogy (I. shapeless-serialization, II. shapeless-builder, III. shapeless-commandline) of shapeless-based libraries that I recently cooked up to both deepen my understanding of Scala and to scratch some technical itches. I hope you find it educational, interesting, and potentially helpful!
import com.github.harveywi.commandline._
import scalaz.{ Success, Failure }
import shapeless._
/**
* Example provided by https://github.com/Rogach/scallop/wiki/Basic-usage
*/
case class BasicUsage(bananas: Option[Int], apples: Int, name: String)
object BasicUsage extends App {
// An optional parameter
val bananas = Opt[Option[Int]](
'b',
"Number of bananas",
"BananaCount",
None,
longName = "bananas")
// Two required parameters
val apples = Param[Int]("apples")
val name = Param[String]("name")
// Description of the program (needed for generating a pretty-printed usage
// message)
val description = CommandDescription(
name = "basic-usage",
quickBlurb = "A demonstration of basic CommandLineParser usage.",
details = "Any additional notes that might helpful to potential users of " +
"your software should go here. This stuff is printed at the bottom " +
"of the usage message. Don't forget to include " +
"https://my.fsf.org/donate!",
version = "1.0")
// Build a CommandLineParser[BasicUsage] with the given optional and
// required parameters
val cmd = CommandLineParser.
builder(description, apply _).
setOpts(bananas :: HNil).
setParams(apples :: name :: HNil).
build()
// Yesssss!
assert(cmd.parse("-b 10 4 bigBunny") ==
Success(BasicUsage(Some(10), 4, "bigBunny")), "Noooooo!")
}import com.github.harveywi.commandline._
import scalaz.{ Success, Failure }
import shapeless._
/**
* Example taken from https://github.com/Rogach/scallop#fancy-things
*
* Currently, the KeyValue options require the option flag to appear before
* each key=value pair, though this should not be too much trouble to fix in a
* later version.
*/
case class FancyThings(props: Map[String, String], firstListName: String,
firstList: List[Int], secondListName: String, secondList: List[Double])
object FancyThings extends App {
val props = KeyValue[String, String](
'E', "String-String properties", "keyString", "valueString",
longName = "props")
val firstListName = Param[String]("firstListName")
val firstList = Param[List[Int]]("firstList")
val secondListName = Param[String]("secondListName")
val secondList = Param[List[Double]]("secondList")
val desc = CommandDescription(
"fancy-things",
"A demonstration of fancy things.",
"There are no additional notes.", "1.0")
val cmd = CommandLineParser.
builder(desc, apply _).
setOpts(props :: HNil).
setParams(firstListName :: firstList :: secondListName :: secondList ::
HNil).build()
assert(cmd.parse("-Ekey1=value1 -E key2=value2 -E key3=value3 " +
"first 1 2 3 second 4 5 6") ==
Success(FancyThings(
Map("key1" -> "value1", "key2" -> "value2", "key3" -> "value3"),
"first", List(1, 2, 3),
"second", List(4.0, 5.0, 6.0))))
}import com.github.harveywi.commandline._
import scalaz.{ Success, Failure }
import shapeless._
import java.io.File
/**
* Note that optional parameters must precede required (positional) parameters
* in the case class constructor's list of parameters.
*/
case class OptionTypesAndDefinitions(
a: Int, // put optional parameters at the beginning
b: String,
c: Option[Float],
d: Option[Double],
e: Short,
f: Long,
g: File,
h: Boolean,
i: Map[String, Int],
j: List[Int], // put required parameters at the end
k: String,
l: List[Double],
m: Int)
object OptionTypesAndDefinitions extends App {
// Plain old options with default values
val a = Opt[Int]('a', "Description for a", "Int", 42, longName = "alpha")
val b = Opt[String]('b', "Description for b", "Int", "empty")
// Options of type scala.Option[_]
val c = Opt[Option[Float]]('c', "Description for c", "Int", None)
val d = Opt[Option[Double]]('d', "Description for d", "Int", None)
// Built-in constraints for numerical parameters. Here, we ensure that
// 0 <= e <= 32767
val e = Opt[Short]('e', "Description for e", "Short", 100).lteq(32767).gteq(0)
// Custom constraints. Note that they can be chained together as shown.
val f = Opt[Long]('f', "Description for f", "Long", 0L).
require(_ % 2 == 0, "Value must be even").require { x =>
if (x == 42) {
Failure("42 is really inappropriate")
} else if (x == 100) {
Success(Int.MaxValue)
} else {
Failure("The only way to succeed here is to set '-f' to be 100")
}
}
// Some built-in constraints for files
val g = Opt[File]('g', "Description for g", "File",
new File("/dev/null")).fileExists.fileIsDirectory
// Flags correspond to Boolean parameters with default value = false
val h = Flag('h', "Description for h",
longName = "really-really-long-name-for-h")
// KeyValue[K, V] instances correspond to Map[K, V] parameters.
val i = KeyValue[String, Int]('i', "Description for i", "keyName", "Int")
// Positional parameters.
val j = Param[List[Int]]("j")
val k = Param[String]("k").require(_.contains("asdf"),
"Parameter 'k' must contain substring 'asdf'.")
val l = Param[List[Double]]("l")
val m = Param[Int]("m").gt(0).lteq(42)
val desc = CommandDescription(
name = "option-types-and-definitions",
quickBlurb = "A demonstration of different option types and definitions.",
details = "IN the following pages I offer nothing more than simple " +
"facts, plain arguments, and common sense: and have no other " +
"preliminaries to settle with the reader, than that he will divest " +
"himself of prejudice and prepossession, and suffer his reason and his " +
"feelings to determine for themselves that he will put on, or rather " +
"that he will not put off, the true character of a man, and generously " +
"enlarge his views beyond the present day.",
version = "1.0")
val cmd = CommandLineParser.builder(desc, apply _).
setOpts(a :: b :: c :: d :: e :: f :: g :: h :: i :: HNil).
setParams(j :: k :: l :: m :: HNil).
build()
println(cmd.usage)
}Here is the output of the above program:
Usage: option-types-and-definitions [OPTIONS] j k l m
Overview: A demonstration of different option types and definitions.
Version: 1.0
The [OPTIONS] section supports the following flags and optional arguments:
-a, --alpha=Int Description for a
-b Int Description for b
-c Int Description for c
-d Int Description for d
-e Short Description for e
-f Long Description for f
-g File Description for g
-h, --really-really-long-name-for-h
Description for h
-i <keyName>=<Int> Description for i
IN the following pages I offer nothing more than simple facts, plain arguments,
and common sense: and have no other preliminaries to settle with the reader,
than that he will divest himself of prejudice and prepossession, and suffer his
reason and his feelings to determine for themselves that he will put on, or
rather that he will not put off, the true character of a man, and generously
enlarge his views beyond the present day.
import com.github.harveywi.commandline._
import scalaz.{ Success, Failure }
import shapeless._
object Subcommands extends App {
trait AppleSubcommand
case class Apple(isBig: Boolean, listOfInts: List[Int],
subcommand: AppleSubcommand)
object Apple {
val description = CommandDescription(
name = "apple",
quickBlurb = "Quick blurb goes here.",
details = "Details go here.",
version = "1.0")
val opts = Flag('b',
"Designates that the apple tree/pie is big (as opposed to small). " +
"By default, trees and pies are not big.", longName = "is-big") :: HNil
val params = Param[List[Int]]("int1 int2 ...") :: HNil
val subcommands = Tree.cmd :: Pie.cmd :: HNil
val cmd = CommandLineParser.
builder(description, apply _).
setOpts(opts).
setParams(params).
setSubcommands(subcommands).
build()
}
case class Tree(kindOfTree: String, howMany: Int) extends AppleSubcommand
object Tree {
val params = Param[String]("kindOfTree") :: Param[Int]("howMany") :: HNil
val description = CommandDescription(
"tree", "quickBlurb goes here", "some details", "1.0")
val cmd = CommandLineParser.
builder(description, apply _).
setParams(params).
build()
}
case class Pie(calories: Long, numSlices: Int) extends AppleSubcommand
object Pie {
val params = Param[Long]("calories") :: Param[Int]("numSlices") :: HNil
val description = CommandDescription(
"pie", "quickBlurb goes here", "some details", "1.0")
val cmd = CommandLineParser.
builder(description, apply _).
setParams(params).
build()
}
assert(Apple.cmd.parse("-b 1 2 3 4 5 tree tall 42") ==
Success(Apple(true, List(1, 2, 3, 4, 5), Tree("tall", 42))))
assert(Apple.cmd.parse("tree tall 42") ==
Success(Apple(false, List(), Tree("tall", 42))))
assert(Apple.cmd.parse("-b 1 2 3 4 5 pie 2400 6") ==
Success(Apple(true, List(1, 2, 3, 4, 5), Pie(2400L, 6))))
assert(Apple.cmd.parse("pie 2400 6") ==
Success(Apple(false, List(), Pie(2400L, 6))))
}For more examples, see the test specifications here and the additional examples here.
This library requires Scala 2.10, shapeless 1.2.3, and scalaz 7.
Scaladoc is available here.
Feel free to contact me (harveywi at cse dot ohio-state dot edu). Thanks!
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