Yuriy Pitomets Pitometsu

tl;dr Serokell is hiring Nix DevOps Engineers

Hi! We’re Serokell – a company with about 30 Haskellers working on a bunch of blockchain-related projects (like Cardano or TeachMePlease). We are hiring SREs and a Head of IT Operations that can work with Nix (yay Nix!) and know some Haskell. The job is fully remote.

A bit more about us

Alternative to the Church, Scott and Parigot encodings of data on the Lambda Calculus.

When it comes to encoding data on the pure λ-calculus (without complex extensions such as ADTs), there are 3 widely used approaches.

Church Encoding

The Church Encoding, which represents data structures as their folds. Using Caramel’s syntax, the natural number 3 is, for example. represented as:

0 c0 = (f x -> x)
1 c1 = (f x -> (f x))
2 c2 = (f x -&gt; (f (f x)))

Лучший, на мой взгляд, источник - Category theory for programmers by Bartosz Milewski. Seattle, Summer 2016 - видео лекции. Additional material at https://bartoszmilewski.com/2014/10/28/category-theory-for-programmers-the-preface/. Версия в pdf: https://github.com/hmemcpy/milewski-ctfp-pdf
Теория категорий на JavaScript. Часть 1. Категория множеств и Введение в преобразование моделей
Теория категорий для программистов, Функторы Седьмая глава из серии статей, указаны ссылки на предыдущие статьи.
От математики к обобщенному программированию Ориг.название From Mathematics to Generic Programming. Авторы Александр Степанов, Дэниэл Э. Роуз.
Категория Hask о теории категорий в контексте системы типов язы

IntelliJ and recursive data structures

You may need to override toString on any recursive or deeply-nested data structure, since IntelliJ will ask the Java Debugger (JDB) to call toString all the time. This will blow up your memory.

Remote debugging

Useful for any number of reasons: testing on a different OS, using lots of memory/cpu resources you don't have locally, etc.

See an Intellij / IDEA guide for background.

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Reddit discussion.

Disclaimer 1: Type classes are great but they are not the right tool for every job. Enjoy some balance and balance to your balance.

Disclaimer 2: I should tidy this up but probably won’t.

Disclaimer 3: Yeah called it, better to be realistic.

Type classes are a language of their own, this is an attempt to document features and give a name to them.

	// This example shows how higher-kinded types can be emulated in Swift today.
	// It acheives correct typing at the cost of some boilerplate, manual lifting and an existential representation.
	// The technique below was directly inspired by the paper Lightweight Higher-Kinded Polymorphism
	// by Jeremy Yallop and Leo White found at http://ocamllabs.io/higher/lightweight-higher-kinded-polymorphism.pdf

	/// `ConstructorTag` represents a type constructor.
	/// `Argument` represents an argument to the type constructor.
	struct Apply<ConstructorTag, Argument> {
	/// An existential containing a value of `Constructor<Argument>`
	/// Where `Constructor` is the type constructor represented by `ConstructorTag`

	// https://stackoverflow.com/questions/44309520/my-coproduct-encoding-is-ambiguous

	import io.circe._, io.circe.generic.semiauto._
	import io.circe.shapes._, io.circe.syntax._
	import shapeless._, shapeless.union._, shapeless.syntax.singleton._

	object Main extends App {
	object model {
	case class A(a: String)
	case class B(a: String, i: Int)

	{-# LANGUAGE GeneralizedNewtypeDeriving #-}

	module Language.HigherRank.Main
	( Expr(..)
	, EVar(..)
	, Type(..)
	, TVar(..)
	, TEVar(..)
	, runInfer
	) where