channingwalton

import scalaz._
import Scalaz._
import scalaz.effects._

import java.io._

/**
 * Background reading:
 * http://www.stackmob.com/2011/12/scalaz-post-part-2/
 * http://blog.sigfpe.com/2007/11/io-monad-for-people-who-simply-dont.html

channingwalton

object Generics {
  import shapeless.HList
  import shapeless.Nat
  import shapeless.Nat._
  import shapeless._

  trait <[A <: Nat, B <: Nat]
  implicit def lt1[B <: Nat] = new <[_0, Succ[B]] {}
  implicit def lt2[A <: Nat, B <: Nat](implicit lt: A < B) = new <[Succ[A], Succ[B]] {}

channingwalton

import scala.xml.NodeSeq

object RenderExample {

  object Model {

    trait Toy
    case class Bike extends Toy
    case class Train extends Toy

channingwalton

import scalaz._
import Scalaz._

/**
 * Use the state monad to 'process a trade' and store the new trade.
 * As well as processing the trade, handle validation errors.
 */
object StateMonad extends App {

  case class Trade(info: String)

channingwalton

object KleisliValidation extends App {
  import scalaz._
  import Scalaz._
  import scala.util.control.Exception._

  type EValidation[+T] = Validation[String, T]
  implicit val binding = new Bind[EValidation] {
    def map[A, B](fa: EValidation[A])(f: A => B): EValidation[B] = fa.map(f)
    def bind[A, B](fa: EValidation[A])(f: A => EValidation[B]): EValidation[B] = fa.flatMap(f)
  }

channingwalton

object KleisliValidation extends App {
  import scalaz._
  import Scalaz._
  import scala.util.control.Exception._

   implicit def vm = Validation.validationMonad[String]

  type EValidation[+T] = Validation[String, T]
  
  def toDouble(s: String): EValidation[Double] = allCatch.either(s.toDouble).fold(_.toString.fail, _.success)

channingwalton

@channingwalton Recently read »I, Robot« from Asimov. The short stories are entertaining and very thoughtful.

@channingwalton I would like a wizard where I tell it I like Asimov (especially Daneel and Giskard) and Clarke, and it recommends others.

@channingwalton pretty much anything by Alastair Reynolds. House of Suns is particularly great.

@channingwalton I’ve enjoyed the Laundry novels by Charles Stross.

@channingwalton "Wool" series by Hugh Howey.

channingwalton

// Inspired by http://dave.fayr.am/posts/2012-10-4-finding-fizzbuzz.html
object FizzBuzz extends App {
  import scalaz._
  import Scalaz._

  def fizzbuzz(i: Int) = ((i % 3 == 0) option "fizz") |+| ((i % 5 == 0) option "buzz") | i.shows 
  
  for (i <- 1 to 100) {println(i + " " + fizzbuzz(i))}
}

channingwalton

package stereotypes

import shapeless._
import Searchable._

object FunctionThisUp {

  // pretend we have some case classes - they needn't be ours of course
  case class Name(name: String)
  case class Description(description: String)

channingwalton

trait FooComponent {

  def bar: BarComponent#Bar

  case class Foo(foofy: String)
}

trait BarComponent {
  def foo: FooComponent#Foo