Ivan Demchenko ivan-demchenko

Lately, I've been working on design systems. I like functional programming, strictly-typed languages and the Hindley–Milner type systems.

ivan-demchenko / App.tsx

Last active October 15, 2024 06:36

TypeScript + React safe API handling

	import { FC } from "react";
	import { HttpError, apiErrorToStr, BlogDataService, Post } from "./api.service";
	import { useListPosts } from "./api.hooks";
	import { assertExhaustive } from "./utils";

	const ShowLoading: FC = () => (
	<div className="p-4 border border-blue-700 bg-blue-100">Loading...</div>
	);

	const ShowError: FC<{ error: HttpError }> = ({ error }) => (

ivan-demchenko / package.json

Created October 15, 2019 19:37

Rollup for React with TypeScript and SVG icons

ivan-demchenko / index.html

Created August 11, 2019 12:23

JS Bin // source https://jsbin.com/cilusoc

	<!DOCTYPE html>
	<html>
	<head>
	<meta name="description" content="Merge Linked Lists">
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width">
	<title>JS Bin</title>
	</head>
	<body>

ivan-demchenko / com.user.automaticbackups.plist

Last active October 28, 2018 05:45

Automatic backup with notifications and rsync

	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
	<plist version="1.0">
	<dict>

	<key>Label</key>
	<string>com.idemchenko.automaticbackups</string>

	<key>StandardOutPath</key>
	<string>/tmp/autoBackup.stdout</string>

ivan-demchenko / functions.fish

Last active June 6, 2018 03:58

fish git functions

	// ~/.config/fish/functions/gb.fish
	function gb
	set _curr_git_branch (git branch ^/dev/null \| grep \* \| sed 's/* //')

	echo ">>> Rebasing $_curr_git_branch onto master <<<"

	gco master
	gpl
	gpl origin master
	gco $_curr_git_branch;

ivan-demchenko / recursive-monadic-fn.js

Last active October 23, 2017 01:16

Async recursion

	const daggy = require('daggy');
	const Task = require('data.task');
	const path = require('path');
	const fs = require('fs');
	const { sequence } = require('ramda');

	// type Entity
	// = File String
	// \| Dir String (List Entity)
	const Entity = daggy.taggedSum('Entity', {

ivan-demchenko / functors.ts

Last active March 28, 2017 07:27

This is my experiment to implement a functor type class using TypeScript

	interface Functor<A> {
	fmap<B>(f: (x: A) => B): Functor<B>
	}

	const fmap = <A, B>(f: (x: A) => B) => (fa: Functor<A>): Functor<B> => fa.fmap(f);

	//=== String
	interface String extends Functor<String> {
	}

ivan-demchenko / quickStart.js

Last active September 12, 2016 07:26

Two most important functions for functional js

	/**
	* Here are two essential functions for functional style in JavaScript.
	* Unfortunately, functions are not curried by default in JS.
	* Also, there is no function composition operator in JS.
	* Thus, we have to implement these on our own.
	**/
	const comp = (...fns) => (...args) =>
	fns.reduceRight((res, fn) => fn(...[].concat(res)), args);

	const curryN = (num, fn) => (...args) =>

ivan-demchenko / preloader-or-image.js

Last active July 24, 2017 02:49

Show the pre-loader when image loading takes more than X milliseconds

	// just a helper
	var $ = document.querySelector.bind(document);

	// "show me the next image" button
	var nextImage = Bacon.fromEvent($('#next'), 'click');

	// this button simulated "onload" event for the img tag
	var img = Bacon.fromEvent($('#loaded'), 'click').map(_ => 'image.jpg.' + Math.random());

	// We need a stream that will be ended either on its own or by another stream.

ivan-demchenko / lamda-calculus-es6.js

Created January 22, 2016 15:23

	// This is the implmenetation of some of the lamdas from lamda calculus
	// https://en.wikipedia.org/wiki/Lambda_calculus
	console.clear();

	const log = function(x) {
	console.log('log: ' + x);
	return x;
	}

	// Boolean: