ghoseb

;;
;; NS CHEATSHEET
;;
;; * :require makes functions available with a namespace prefix
;;  and optionally can refer functions to the current ns.
;;
;; * :import refers Java classes to the current namespace.
;;
;; * :refer-clojure affects availability of built-in (clojure.core)
;;   functions.

michalmarczyk

(defmacro letrec [bindings & body]
  (let [bcnt (quot (count bindings) 2)
        arrs (gensym "bindings_array")
        arrv `(make-array Object ~bcnt)
        bprs (partition 2 bindings)
        bssl (map first bprs)
        bsss (set bssl)
        bexs (map second bprs)
        arrm (zipmap bssl (range bcnt))
        btes (map #(walk/prewalk (fn [f]

limitedmage

import math
import random

class Qubit:
    def __init__(self, a = 1, b = 0):
        '''Initialize a single qubit'''
        self.zero = complex(a)
        self.one  = complex(b)

    def xgate(self):

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

debasishg

trait MyOption[+A] {
  // single abstract method
  def cata[X](some: A => X, none: => X): X

  import MyOption._

  def map[B](f: A => B): MyOption[B] = cata(f andThen some, none)

  // Also
  // def map[B](f: A => B): MyOption[B] = flatMap(f andThen some)

krasserm

import scalaz._
import Scalaz._

object MonadTransformerExamples {
  def main(args: Array[String]) = run

  def run {
    // ------------------------------------------------------
    // Combined Option/Option
    // ------------------------------------------------------

retronym

package demo
  
class Coder(words: List[String]) {

  private val mnemonics = Map(
      '2' -> "ABC", '3' -> "DEF", '4' -> "GHI", '5' -> "JKL", 
      '6' -> "MNO", '7' -> "PQRS", '8' -> "TUV", '9' -> "WXYZ")
      
  /** Invert the mnemonics map to give a map from chars 'A' ... 'Z' to '2' ... '9' */
  private val charCode: Map[Char, Char] = 

missingfaktor

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

object ExperimentingWithIo {

  def main(args: Array[String]): Unit = {

    val i1: IO[Unit] = for {
      _ <- putStrLn("What's your name?")

milessabin

def unexpected : Nothing = sys.error("Unexpected invocation")

// Encoding for "A is not a subtype of B"
trait <:!<[A, B]

// Uses ambiguity to rule out the cases we're trying to exclude
implicit def nsub[A, B] : A <:!< B = null
implicit def nsubAmbig1[A, B >: A] : A <:!< B = unexpected
implicit def nsubAmbig2[A, B >: A] : A <:!< B = unexpected

retronym

package scalaz.example


object Reader extends App {

  /**
   * Manual propagation of the environment (in the example, `contextRoot`.)
   */
  object Config0 {
    def fragment1(contextRoot: String) = <a href={contextRoot + "/foo"}>foo</a>