palutz

Haskell at Work - Web API

(from Haskell training)

---

git checkout chapter2

palutz

Haskell Cheatsheet

(from Haskell Training)

declarations and types

When we declare a value f, we usually first write the type of f and then, on a separate line, its actual value. For example

fortytwo :: Int

palutz

Bitcoin Privacy Introduction

Why privacy matters in Bitcoin

Celsius recent court filings provided a terrible and arguably avoidable loss of privacy for many of its customers, and will likely have chilling ripple effects for a long time to come. The goal of this presentation-turned-writeup is to give some context so that the reader can understand the consequences of such incidents and where to find more detailed information in order to mitigate such risks, and the tradeoffs that entails.

palutz

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;

contract HelloWorld {    // capital letter for contract name
    string text_ = "Hello World";

    function helloworld() public view returns (string memory) {
        //return text_;
        bytes memory bm = helloTest(text_, "!!!");
        return string(bm);

palutz

#!/usr/bin/env python3
# Copyright (c) 2017-2021 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""An example functional test

The module-level docstring should include a high-level description of
what the test is doing. It's the first thing people see when they open
the file and should give the reader information about *what* the test

palutz

import Data.Char (intToDigit, digitToInt)

-- Ading 2 binary int with reminder
addB :: Int -> Int -> Int -> (Int, Int)
addB x y r = if z >= 2 then (1, z - 2) else (0, z)
                where
                z = x + y + r

-- recursive adder combining the 2 streams of Char and return the reversed combination 
-- (Char -> Int) = convert Char to Int. It can be customise to add custom logic

palutz

// simple flink job

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.api.common.functions.FilterFunction;

public class Example {

    public static StreamExecutionEnvironment getEnvironment(env: String) {
        StreamExecutionEnvironment env;

palutz

// Scala Bridge - Code to show how to declare type classes in Scala (from Scala with Cats)

sealed trait Json
final case class JsObject(get: Map[String, Json]) extends Json
final case class JsString(get: String) extends Json
final case class JsNumber(get: Double) extends Json
final case object JsNull extends Json

trait JsonWriter[A] {
  def write(value: A): Json

palutz

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

palutz

/**
 * D Holbrook
 *
 * Code Club: PO1
 *
 * (*) Define a binary tree data structure and related fundamental operations.
 *
 * Use whichever language features are the best fit (this will depend on the language you have selected).  The following operations should be supported:
 *
 *    Constructors