[scala][play2] monadic fizzbuzz

Application.scala

package controllers

import play.api._
import play.api.mvc._

import EA._

object Application extends Controller {
  implicit def either2Bind(s:Either[String,Int]) = new Bind(s)
  implicit def int2Bind(x:Int) = new Bind[String,Int](Right(x))
  def setup = (div:Int,str:String) => (i:Int) => if(i % div == 0) str 終了 else i 継続
  def fizz = setup(3,"Fizz")
  def buzz = setup(5,"Buzz")
  def fizzbuzz = (i:Int) => (fizz(i),buzz(i)) match {
    case (Left(x),Left(y)) => x + y 終了
    case _ => i                     継続
  }

  def index(start:Int,end:Int) = EitherAction {_ =>
    val result = (start to end) map {_ >>= fizzbuzz >>= fizz >>= buzz merge}
    Ok("%d => %d\n%s".format(start,end,result.mkString("[",",","]"))) 終了
  }
}

routes

# Routes
# This file defines all application routes (Higher priority routes first)
# ~~~~

# Home page
GET     /:start/:end                     controllers.Application.index(start:Int,end:Int)

# Map static resources from the /public folder to the /assets URL path
GET     /assets/*file               controllers.Assets.at(path="/public", file)

play2 + scalaでmanadicなfizzbuzzを書いてみた。

• app/controller/Application.scala
• app/controller/EitherAction.scala
• conf/routes

をそれぞれ置き換えれば動きます。

EitherActionはこちらを参照してください。

https://gist.github.com/2626167

http://localhost:9000/1/100

で1から100までのfizzbuzzが表示されます。