billwanjohi's solution to Bob on the Scala track

Instructions

Test suite

Solution

Bob is a lackadaisical teenager. In conversation, his responses are very limited.

Bob answers 'Sure.' if you ask him a question.

He answers 'Whoa, chill out!' if you yell at him.

He answers 'Calm down, I know what I'm doing!' if you yell a question at him.

He says 'Fine. Be that way!' if you address him without actually saying anything.

He answers 'Whatever.' to anything else.

The Scala exercises assume an SBT project scheme. The exercise solution source should be placed within the exercise directory/src/main/scala. The exercise unit tests can be found within the exercise directory/src/test/scala.

To run the tests simply run the command sbt test in the exercise directory.

For more detailed info about the Scala track see the help page.

Source

Inspired by the 'Deaf Grandma' exercise in Chris Pine's Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=06

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

BobTest.scala

import org.scalatest.{Matchers, FunSuite}

/** @version 1.4.0 */
class BobTest extends FunSuite with Matchers {

  test("stating something") {
    Bob.response("Tom-ay-to, tom-aaaah-to.") should be("Whatever.")
  }

  test("shouting") {
    pending
    Bob.response("WATCH OUT!") should be("Whoa, chill out!")
  }

  test("shouting gibberish") {
    pending
    Bob.response("FCECDFCAAB") should be("Whoa, chill out!")
  }

  test("asking a question") {
    pending
    Bob.response("Does this cryogenic chamber make me look fat?") should be(
      "Sure.")
  }

  test("asking a numeric question") {
    pending
    Bob.response("You are, what, like 15?") should be("Sure.")
  }

  test("asking gibberish") {
    pending
    Bob.response("fffbbcbeab?") should be("Sure.")
  }

  test("talking forcefully") {
    pending
    Bob.response("Let's go make out behind the gym!") should be("Whatever.")
  }

  test("using acronyms in regular speech") {
    pending
    Bob.response("It's OK if you don't want to go to the DMV.") should be(
      "Whatever.")
  }

  test("forceful question") {
    pending
    Bob.response("WHAT THE HELL WERE YOU THINKING?") should be(
      "Calm down, I know what I'm doing!")
  }

  test("shouting numbers") {
    pending
    Bob.response("1, 2, 3 GO!") should be("Whoa, chill out!")
  }

  test("no letters") {
    pending
    Bob.response("1, 2, 3") should be("Whatever.")
  }

  test("question with no letters") {
    pending
    Bob.response("4?") should be("Sure.")
  }

  test("shouting with special characters") {
    pending
    Bob.response("ZOMG THE %^*@#$(*^ ZOMBIES ARE COMING!!11!!1!") should be(
      "Whoa, chill out!")
  }

  test("shouting with no exclamation mark") {
    pending
    Bob.response("I HATE THE DMV") should be("Whoa, chill out!")
  }

  test("statement containing question mark") {
    pending
    Bob.response("Ending with ? means a question.") should be("Whatever.")
  }

  test("non-letters with question") {
    pending
    Bob.response(":) ?") should be("Sure.")
  }

  test("prattling on") {
    pending
    Bob.response("Wait! Hang on. Are you going to be OK?") should be("Sure.")
  }

  test("silence") {
    pending
    Bob.response("") should be("Fine. Be that way!")
  }

  test("prolonged silence") {
    pending
    Bob.response("          ") should be("Fine. Be that way!")
  }

  test("alternate silence") {
    pending
    Bob.response("										") should be("Fine. Be that way!")
  }

  test("multiple line question") {
    pending
    Bob.response("""
Does this cryogenic chamber make me look fat?
No.""") should be("Whatever.")
  }

  test("starting with whitespace") {
    pending
    Bob.response("         hmmmmmmm...") should be("Whatever.")
  }

  test("ending with whitespace") {
    pending
    Bob.response("Okay if like my  spacebar  quite a bit?   ") should be(
      "Sure.")
  }

  test("other whitespace") {
    pending
    Bob.response("""
                 	""") should be("Fine. Be that way!")
  }

  test("non-question ending with whitespace") {
    pending
    Bob.response("This is a statement ending with whitespace      ") should be(
      "Whatever.")
  }
}

import scala.collection.GenSeq

object Empty {
  /**
    * Taking advantage of extractor objects to
    * express patterns separately
    */
  def unapply(str: String) = {
    if (str == "") Some(str) else None
  }
}

object Shouty {
  def unapply(str: String) = {
    val hasChars = (str: String, x: GenSeq[Char]) =>
      !str.intersect(x).isEmpty
    val hasUpper = (str: String) =>
      hasChars(str, 'A' to 'Z')
    val hasNoLower = (str: String) =>
      !hasChars(str, 'a' to 'z')
    if (hasUpper(str) && hasNoLower(str))
      Some(str) else None
  }
}

object Question {
  def unapply(str: String) = {
    if (str.endsWith("?")) Some(str) else None
  }
}

object Bob {
  def response(statement: String): String = {
    val trimmed = statement.trim()
    trimmed match {
      case Empty(_) => "Fine. Be that way!"
      // I wanted to do something like:
      // `case Shouty(_) & Question(_)`
      case Shouty(x) if x.endsWith("?") =>
        "Calm down, I know what I'm doing!"
      case Shouty(_) => "Whoa, chill out!"
      case Question(_) => "Sure."
      case _ => "Whatever."
    }
  }
}

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billwanjohi's Reflection

My solution was inspired by a similar one I made in F# with partial active patterns.

billwanjohi's solution

to Bob in the Scala Track

Source

Submitting Incomplete Solutions

BobTest.scala

Community comments

billwanjohi's Reflection

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