paulp

Hello scala, my old friend
I've come to take you home again
Because a feature slowly creeping
left me plagued with doubts and weeping
and the version that was tagged in the repo
just has to go
it lacks the signs of soundness

On sleepless nights I hacked alone
applying ant and other tools of stone

xeno-by

19:07 ~/Projects/Kepler_typemacros/sandbox (topic/typemacros)$ scalac Macros.scala
19:07 ~/Projects/Kepler_typemacros/sandbox (topic/typemacros)$ scala -cp .
Welcome to Scala version 2.10.1-20121120-175733-b60f5bcf2c (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_37).
Type in expressions to have them evaluated.
Type :help for more information.

scala> class C extends AnyRef with Macros.Foo[Int]("2")
defined class C

scala> new C().hello

robinsloan

require "rubygems"
require "twitter"
require "json"

# things you must configure
TWITTER_USER = "your_username"
MAX_AGE_IN_DAYS = 1 # anything older than this is deleted

# get these from dev.twitter.com
CONSUMER_KEY = "your_consumer_key"

mpilquist

import scalaz._
import Scalaz._
import scalaz.iteratee._
import EnumeratorT._

def counter[A, F[+_]: Pointed] =
  IterateeT.fold[A, F, Int](0) { (acc: Int, a: A) => acc + 1 }

def count[A, F[+_]: Monad](e: EnumeratorT[A, F]) =
  (counter[A, F] &= e).run

viktorklang

import scala.concurrent._
import scala.collection.mutable.Builder
import scala.collection.generic.CanBuildFrom
import language.higherKinds

/**
 * Linearize asynchrnously applies a given function in-order to a sequence of values, producing a Future with the result of the function applications.
 * Execution of subsequent entries will be aborted if an exception is thrown in the application of the function.
 */
def linearize[T, U, C[T] <: Traversable[T]](s: C[T])(f: T => U)(implicit cbf: CanBuildFrom[C[T], U, C[U]], e: ExecutionContext): Future[C[U]] = {

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

corruptmemory

/**
 * A silly example using Kleisli composition of DB operations
 * Based on an idea from Runar Bjarnason found here:
 *   https://groups.google.com/d/msg/scala-debate/xYlUlQAnkmE/FteqYKgo2zUJ
 *
 * Uses Scalaz7
 *
 * @author <a href="mailto:[email protected]">Jim Powers</a>
 */
object Monadic {

debasishg

/**
 * |@| is a helper function that helps you accumulate applicative functors. It gives you an ApplicativeBuilder (it's part of
 * the implementation though) through which you accumulate your applicatives just as you would using the Builder pattern of
 * the GoF in the OO world. Once you have all the applicatives you can pass it a function that will be applied to all the 
 * values that you have accumulated so far. e.g.
 */

scala> (1.some |@| 2.some) apply {_ + _}
res1: Option[Int] = Some(3)

raichoo

class MMethod[M, A1, A2, R](f: (A1, A2) => R) {                                                                      
  def apply(a1: A1, a2: A2): R = f(a1, a2)
}

class MultiMethod {
  def apply[A1, A2, R](a1: A1, a2: A2)
                      (implicit mm: MMethod[this.type, A1, A2, R]): R =
    mm(a1, a2)

  // use a singleton type to attach the resulting implicit to our multimethod

viktorklang

trait Enum { //DIY enum type
  import java.util.concurrent.atomic.AtomicReference //Concurrency paranoia

  type EnumVal <: Value //This is a type that needs to be found in the implementing class

  private val _values = new AtomicReference(Vector[EnumVal]()) //Stores our enum values

  //Adds an EnumVal to our storage, uses CCAS to make sure it's thread safe, returns the ordinal
  private final def addEnumVal(newVal: EnumVal): Int = { import _values.{get, compareAndSet => CAS}
    val oldVec = get