ekozhura

Reposted from Qiita

For almost a year now, I've been using this "flux" architecture to organize my React applications and to work on other people's projects, and its popularity has grown quite a lot, to the point where it shows up on job listings for React and a lot of people get confused about what it is.

Why I'm tired of using and teaching flux

There are a billion explainations on the internet, so I'll skip explaining the parts. Instead, let's cut to the chase -- the main parts I hate about flux are the Dispatcher and the Store's own updating mechanism.

If you use a setup similar to the examples in facebook/flux, and you use flux.Dispatcher, you probably have this kind of flow:

ekozhura

open Printf

type ('a, 'b) result = 
  | Success of 'a * 'b
  | Failure of string

type 'a parser = Parser of (string -> ('a, string) result)

let run_parser p i = match p with
  | Parser fn -> fn i;;

ekozhura

module AudioNode = {
  type audio_node;
};

module AudioParam = {
  type audio_param;
  [@bs.send] external setValue: audio_param => float => float => unit = "setValueAtTime"; 
};

module AudioSourceNode = {

ekozhura

Notes on FRA implementation (functional reactive animation)

Inspired by Fran (by Conal Elliott) and "The Haskell School of Expression" (by Paul Hudak).

Github: https://github.com/ekozhura/fra (work in progress).

Transform type

Let's define a type Transform:

ekozhura

type lazylist('a) =
  | Cons('a, unit => lazylist('a));

let rec lseq = n => Cons(n, () => lseq(n + 1));

let lhd = (Cons(n, _)) => n;
let ltl = (Cons(_, tf)) => tf();

let rec ltake = (Cons(h, tf), n) =>
  switch (n) {

ekozhura

/**
 * This code was used as a part of PoC, done for my talk at ReactKyiv meetup:
 * https://animationsslides.brutallo.now.sh/#/
 * 
 * 
 * Emoji animations were inspired by this article:
 * https://matthewrayfield.com/articles/animating-urls-with-javascript-and-emojis/
 */

/**

ekozhura

ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

Convert WAV to MP3, mix down to mono (use 1 audio channel), set bit rate to 64 kbps and sample rate to 22050 Hz:

ekozhura

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

ekozhura

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions

ekozhura

#define DATA_PIN 3 // data
#define CLOCK_PIN 4 // clock
#define RESET_PIN 5 // reset
#define SEVEN_SEGMENTS_LENGTH 17

static byte seven_segments_codes[SEVEN_SEGMENTS_LENGTH] = {
  B10001000,  //  0
  B11101011,  //  1
  B01001100,  //  2
  B01001001,  //  3