channingwalton

def setL[T, A, B](la: Lens[T, A], lb: Lens[T, B])(a:A, b: B)(t: T): T = la.set(lb.set(t, b), a)

def setL[T, A, B, C](la: Lens[T, A], lb: Lens[T, B], lc: Lens[T, C])(a:A, b: B, c: C)(t: T): T = lc.set(setL(la, lb)(a,b)(t), c)

def setL[T, A, B, C, D](la: Lens[T, A], lb: Lens[T, B], lc: Lens[T, C], ld: Lens[T, D])(a:A, b: B, c: C, d: D)(t: T): T = ld.set(setL(la, lb, lc)(a,b, c)(t), d)

channingwalton

object MonadWriterExample extends App {
  import scalaz._
  import Scalaz._

  implicit val monadWriter = EitherT.listenableMonadWriter[Writer, String, String]

  case class Person(firstName: String, age: Int, car: Option[String])

  def notEmpty(s: String) = Option(s).filter(x ⇒ !x.isEmpty && !x.forall(_.isWhitespace)) match {
    case Some(r) ⇒ monadWriter.right[String](r)

channingwalton

object play {
  import scalaz._
  import Scalaz._

  def foo(i: Int) =  if (i > 0) Some(i) else None
 
  def boo(i: Int) =  if (i <= 0) Some(0) else None

  val l = foo _ :: boo _ :: Nil
 

channingwalton

object PartialLensExample extends App {

  import scalaz._
  import Lens._
  import PLens._


  case class Bar(blub: Option[String])
  case class Foo(bar: Option[Bar])

channingwalton

object Trees extends App {

  def zero = '0'

  def repeat(c: Char)(n: Int) = c.toString * n

  def reflect(centre: Char)(s: String) = s.reverse + centre + s

  def pad(w: Int, c: Char)(s: String) = s.padTo(w - 1, c)

channingwalton

 // ------------------------------------------------------
 // Combined List/Option/Either
 // ------------------------------------------------------
object MonadTransformers extends App {
  import scalaz._, Scalaz._
  import EitherT._

  type OptionTList[α] = ({ type λ[α] = OptionT[List, α] })#λ[α]

  val c1: EitherT[OptionTList, String, String] = eitherT[OptionTList, String, String](OptionT[List, \/[String, String]](List(some(\/-("c1a")), some(\/-("c1b")))))

channingwalton

What Changed

I used to automount on OSX by sudo vifs and adding a line like vault.local:/backup /Volumes/backup url auto,url==afp://;AUTH=No%20User%[email protected]/backup 0 0. But that no longer works on Maverick because the system deletes everything in /Volumes on wake/restart/something-or-other.

We are going to create a mount at /mnt/Resources. We need to edit the auto_master to tell it where the automount config for /mnt/Resources lives:

sudo vi /etc/auto_master

Now add this line at the top

channingwalton

object MonoidHomomorphism extends App {

  import scalaz._
  import Scalaz._

  /**
   * Turn any null into the Zero value for its type
   */
  def nullAsZero[T: Monoid : Equal](a: T) = if (a == null) implicitly[Monoid[T]].zero else a

channingwalton

case class Foo[T](x: T) {
  def map[B](f: T => B) = Foo(f(x))
}

object OldWay {

  def combineLatest[T1, T2](e1: Foo[T1], e2: Foo[T2]): Foo[(T1, T2)] = Foo((e1.x, e2.x))

  def combineLatest[T1, T2, T3](e1: Foo[T1], e2: Foo[T2], e3: Foo[T3]): Foo[(T1, T2, T3)] =
    combineLatest(combineLatest(e1, e2), e3) map {

channingwalton

import scalaz._

object LensFu extends App {

  case class FieldValue[T](name: String, v: T)

  case class Field[T, F](name: String, lens: Lens[T, F]) {
    def >=>[G](field: Field[F, G]): Field[T, G] = Field(name + "." + field.name, lens >=> field.lens)
    def get(v: T): FieldValue[F] = FieldValue(name, lens.get(v))
    def set(a: T, b: F): T = lens.set(a, b)