lihaoyi

lihaoyi Ammonite$ amm
Loading...
Welcome to the Ammonite Repl 0.8.0
(Scala 2.11.8 Java 1.8.0_112)
@ {
  val funnyFilter = ammonite.terminal.Filter.simple(" ")((b, c, m) =>
    if (FunnyFrontEnd.nextLine == Nil) (b.take(c) ++ " " ++ b.drop(c), c+1)
    else {
      val head :: tail = FunnyFrontEnd.nextLine
      FunnyFrontEnd.nextReader = new java.io.StringReader(head)

jdegoes

Applied Functional Programming with Scala - Notes

Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

runarorama

// Finally tagless lambda calculus
object Final {
  def varZ[A,B](env1: A, env2: B): A = env1
  def varS[A,B,T](vp: B => T)(env1: A, env2: B): T = vp(env2)
  def b[E](bv: Boolean)(env: E): Boolean = bv
  def lam[A,E,T](e: (A, E) => T)(env: E): A => T = x => e(x, env)
  def app[A,E,T](e1: E => A => T, e2: E => A)(env: E): T = e1(env)(e2(env))

  def testf1[E,A](env: E): Boolean =
    app(lam[Boolean,E,Boolean](varZ) _, b(true))(env)

pchiusano

import scalaz.Applicative
import scalaz.concurrent.Task

/** 
 * This `Applicative[Task]` runs tasks in parallel, by defining
 * `ap` and `apply2` in terms of `mapBoth`. This differs from the
 *  default `Applicative[Task]`, where effects are sequenced 
 *  deterministically, in left to right order.
 */
val T = new Applicative[Task] {

elithrar

A quick "how to" on what you need to do to both setup AND recover a single-server PostgreSQL database using WAL-E

• WAL-E: https://github.com/wal-e/wal-e
• Assuming Ubuntu 12.04 LTS ("Precise")
• We'll be using S3. Make sure you have an IAM in a group with GetObject, ListBucket and PutObject on the bucket you want to use (and that it's not public).

Setup:

1. These packages:

GedowFather

#!/bin/bash
#
# Setup VPN between Debian Linux and VPC G/W.
#   How to use : ./this_script.sh Generic.txt
#
# For connecting IPsec VPN, you need to allow these connections.
# If VPN has global address, you change FORWARD to OUTPUT.
#
#   ex) iptables -A FORWARD -p udp --dport 500 -j ACCEPT
#       iptables -A FORWARD -p tcp --dport 500 -j ACCEPT

viktorklang

object NettyFutureBridge { 
  import scala.concurrent.{ Promise, Future }
  import scala.util.Try
  import java.util.concurrent.CancellationException 
  import org.jboss.netty.channel.{ Channel, ChannelFuture, ChannelFutureListener }

  def apply(nettyFuture: ChannelFuture): Future[Channel] = { 
    val p = Promise[Channel]() 
    nettyFuture.addListener(new ChannelFutureListener { 
      def operationComplete(future: ChannelFuture): Unit = p complete Try( 

patriknw

package example

import java.util.concurrent.ConcurrentHashMap
import java.util.concurrent.ConcurrentLinkedQueue
import com.typesafe.config.Config
import com.typesafe.config.ConfigFactory
import akka.actor.Actor
import akka.actor.ActorContext
import akka.actor.ActorRef
import akka.actor.ActorSystem

folone

case class Reader[T, +A](run: T ⇒ A) {
  def map[B](f: A ⇒ B): Reader[T, B] =
    Reader((r: T) ⇒ f(run(r)))

  def flatMap[B](f: A ⇒ Reader[T, B]): Reader[T, B] =
    Reader((r: T) ⇒ f(run(r)).run(r))

  def &&&[B](x: Reader[T, B]): Reader[T, (A, B)] =
    for {
      a ← this

tmcw

import subprocess
import sys, re
MERC = '+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs'

infile = sys.argv[1]

info_output = subprocess.Popen(['gdalinfo', infile], stdout=subprocess.PIPE).communicate()[0]

size_is_re = re.compile('Size is (?P<width>\d+), (?P<height>\d+)')
size_is = filter(lambda x: x, map(lambda x: size_is_re.match(x), info_output.split('\n')))