dszakallas

Recently I've been writing a graph query engine at Fault Tolerant System Research Group at uni. The frontend is Cypher, a language popularized by Neo Technology shipped OOTB with their graph database Neo4j.

Recently Cypher is getting standardized in an open source and open government initiative under the name openCypher; and other DB vendors, such as the RDBMS giant Oracle are starting to support it.

The language itself is similar to SQL augmented with syntax for graph pattern matching. One of the similarities is the handling of NULL values.

dszakallas

/*
  Immutable bidirectional multimap with unique set of values and keys.
 */
case class BiMultiMap[K, V](
                             forward: Map[K, Set[V]] = Map.empty,
                             backward: Map[V, Set[K]] = Map.empty
                           ) {
  import BiMultiMap._
  def +(kv: (K, Set[V])): BiMultiMap[K, V] = {
    val (nextForward, nextBackward) = kv match {

dszakallas

template<typename T> void f(T&& param); // param is now a universal reference
int x = 27;
const int cx = x; 
const int& rx = x;
f(x);                                   // x is lvalue, so T is int&,
                                        // param's type is also int&
f(cx);                                  // cx is lvalue, so T is const int&,
                                        // param's type is also const int&
f(rx);                                  // rx is lvalue, so T is const int&,
                                        // param's type is also const int&

dszakallas

import scala.reflect.ClassTag

class FixedCapQueue[A: ClassTag](size: Int) {
  val queue: Array[A] = new Array(size)
  var start: Int = 0
  var end: Int = 0
  var empty = size > 0

  def take(): A = {
    if (end == start && empty) throw new Exception("Queue empty")

dszakallas

(ns my-first-clojure-go-routine
  (:require [clojure.core.async :refer :all]))

(defn ping [name chan & [start?]]
  (go (when start? (>! chan 0))
      (loop [i (<! chan)]
        (println name i)
        (>! chan (inc i))
        (if (< i 100) (recur (<! chan)) i))))

dszakallas

dszakallas

Keybase proof

I hereby claim:

• I am dszakallas on github.
• I am david_szakallas (https://keybase.io/david_szakallas) on keybase.
• I have a public key whose fingerprint is 38F9 8FCE 7CED FA3C 04D9 B6FE 9E63 257F 2A73 97BB

To claim this, I am signing this object:

dszakallas

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