akihiro4chawon

  def find2[A](x:A, xs:List[A]):Option[A] = {
    if(xs.nonEmpty){
      if(xs.head == x) Some(xs.head)
      else find2(x, xs.tail)
    } else {
      None
    }
  }
  def find3[A](x:A, xs:List[A]):Option[A] = 
    xs.headOption match {

akihiro4chawon

object BinTreeIterator {
  sealed trait Tree
  case class Node(v: Int, l: Tree, r: Tree) extends Tree
  case object Leaf extends Tree

  def toIterator(node: Tree): Iterator[Int] = {
    def toStream(n: Tree): Stream[Int] = n match {
      case Node(v, l, r) => v #:: toStream(l) #::: toStream(r)
      case Leaf => Stream.empty
    }

akihiro4chawon

import scalaz._
import Scalaz._

object Bubble {
  def bubbleSort[A: Order](xs: List[A]) = xs.unfold[Stream, A] {
    _.foldr[Option[(A, List[A])]](none){ (x, zs) =>
      zs.fold({case (y, ys) => (x lt y).fold((x, y::ys), (y, x::ys))}, (x, nil[A])).some
    }
  }
}

akihiro4chawon

module Main where

import Control.Monad
import Control.Monad.Trans
import Control.Monad.Trans.List
import System.Directory

getAllFilesIn :: FilePath -> IO [FilePath]
getAllFilesIn path = runListT $ getAllFilesIn' path
  where