Alexandre Moreno moleike

Programming Language Zoo

https://realworldocaml.org/v1/en/html/parsing-with-ocamllex-and-menhir.html

A quick overview of the node.js streams interface with basic examples.

This is based on @brycebaril's presentation, Node.js Streams2 Demystified

Overview

Streams are a first-class construct in Node.js for handling data.

Think of them as as lazy evaluation applied to data.

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	const net = require('net');

	const server = net.createServer((c) => {
	// 'connection' listener
	console.log('client connected');
	c.on('end', () => {
	console.log('client disconnected');
	});
	c.write('hello');
	c.pipe(c);

	# Install ARCH Linux with encrypted file-system and UEFI
	# The official installation guide (https://wiki.archlinux.org/index.php/Installation_Guide) contains a more verbose description.

	# Download the archiso image from https://www.archlinux.org/
	# Copy to a usb-drive
	dd if=archlinux.img of=/dev/sdX bs=16M && sync # on linux

	# Boot from the usb. If the usb fails to boot, make sure that secure boot is disabled in the BIOS configuration.

	# Set swedish keymap

	//-------------------------------------------------------------
	//
	// Hypothesis:
	//
	// Promises/A is a Monad
	//
	// To be a Monad, it must provide at least:
	// - A unit (aka return or mreturn) operation that creates a corresponding
	// monadic value from a non-monadic value.
	// - A bind operation that applies a function to a monadic value

	(*
	Interactive approach
	--------------------

	You can copy-paste code into `utop`, provided you load the lwt.unix
	package:

	#use "topfind";;
	#require "lwt.unix";;

	import Data.List

	type Point a = (a,a)

	distance :: Floating a => Point a -> Point a -> a
	distance (a,b) (c,d) = sqrt ((a-c)^ 2 + (b-d)^ 2)

	min_distance_naive :: (Ord a, Floating a) => [Point a] -> a
	min_distance_naive = foldr1 min . loop
	where

	-- randomized quick sort with 3-way partition
	module QuickSort (quicksort) where
	import Data.Array.ST
	import Control.Monad
	import Control.Monad.ST
	import System.Random

	type QA s = STUArray s Int Int

	swap :: Int -> Int -> QA s -> ST s ()

	# -- coding: utf-8 --

	import numpy as np
	import matplotlib.pyplot as plt
	import scipy.integrate as integrate

	# Dimension of image in pixels
	N = 256
	# Number of samples to use for integration
	M = 32