juan_gandhi | Entries tagged with scala

John De Goes is Programming Without Type Classes

Type classes have become a cornerstone of statically-typed functional programming, powering abstractions like monoid and monad. Yet, type classes often have generalized names, which don’t reflect their purpose in specific domains; and they incur higher learning costs, especially when emulated in languages without them.

In this presentation, John De Goes discusses the pros and cons of using type classes, and presents a systematic method for building powerful functional components that do not require type classes. Attendees will learn how to preserve the benefits of principled, algebraic functional programming, without forcing type classes on coworkers or users.

Reference slides

https://tinyurl.com/scala2to3

Юджин Йокота деплойнул sbt в jfrog, вместо чего-то там.

В результате по всей планете билды скальных продуктов сломаны.

Вот это заебись надежность. Я вообще не понимаю, как можно бесконтрольные апдейты устраивать.

Had a discussion yesterday. Basically, about this equality:

scala> "abc": Iterable[Char]
val res0: Iterable[Char] = abc

scala> List('a', 'b', 'c'): Iterable[Char]
val res1: Iterable[Char] = List(a, b, c)

scala> res0 == res1                                                                                                        
val res2: Boolean = true

No surprise, just making sure that it behaves as expected. Two projections are equal.

Вот простые два теста на Котлине.

    Stream.of<String>().forAll {   it.isEmpty() } shouldBe true
    Stream.of<String>().forAll {  !it.isEmpty() } shouldBe true

Не очень понятно, как это непрофессионалы воспримут. Моим студентам требуются усилия обычно.

Послушал тут доклад на мадридском митапе, про munit - ну как-то не вижу смысла; junit надоел хуже горькой редьки, а этот не особо далеко ушел, только что stack trace highlighting. Я уж лучше specs2 продолжу использовать.

Или?

def x: { def k: Int } = new { def k: Int = 42 }

Just figured, `_` in Scala is an example of anaphora.

https://blog.fp-tower.com/monocle-3-a-peek-into-the-future/#1

https://www.youtube.com/embed/o_8uw6BCliU

https://github.com/vpatryshev/presheaf2/blob/master/src/main/scala/com/presheaf/http/HttpsServer.scala

See the readme at https://github.com/vpatryshev/presheaf2 for details.

Что в ScalaZ ноль тестов для OptionT. Я им когда-то навалял тест для finger trees, ну и. Короче, за столько лет если не сбацали, так и все уже, наверно. Хм. Это я хотел поэкспериментировать. Потому что не совсем понимаю причин коммутирования (и могу привести простой контрпример). Пошел смотреть, как оно в typelevel/cats. In short. Have to use cats. Probably not. Will take a look at ZIO later.

https://www.youtube.com/user/FunctionalTV

Ночью приходил енот, помыл кошкину миску. Почему этого енота не записала камера, непонятно.

Regarding type parameters and member types. Say, you have trait T[X]{}. With a certain caveat, you may view it as a functor. If you have trait T { type X }. We have a partial mapping that, given a type, produces X (or not).

We can as well view both as binary relations between types (or profunctors, if we go to categories). One is an inverse of another.

So when you choose which one to prefer, mind the meaning of it.

(inspired by Compall's blog from 2015.

Juan Manuel talks

his slides

his code

John de Goes' opinion

(me: still struggling with all this)

Li Haoyi, Hands-on Scala

https://www.handsonscala.com/

https://www.meetup.com/SF-Types-Theorems-and-Programming-Languages/events/270634414/

Welcome to Scala 2.12.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_92).
Type in expressions for evaluation. Or try :help.

scala> def f(x: Int) = 10 + x -> "ok"
f: (x: Int)(Int, String)

scala> f(10)
res0: (Int, String) = (20,ok)

scala> def g(x: Int) = 20 + x → "oops"
:11: error: overloaded method value + with alternatives:
  (x: Double)Double 
  (x: Float)Float 
  (x: Long)Long 
  (x: Int)Int 
  (x: Char)Int 
  (x: Short)Int 
  (x: Byte)Int 
  (x: String)String
 cannot be applied to ((Int, String))
       def g(x: Int) = 20 + x → "oops"
                          ^

https://github.com/vpatryshev/Categories/blob/master/src/main/scala/math/cat/topos/LawvereTopology.scala

That's in Grothendieck toposes, of course.

S	M	T	W	T	F	S
	1	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16	17	18	19	20
21	22	23	24	25	26	27
28	29	30

Observations

Views from Souths

Entries tagged with scala

tuesday event

scala 3 for scala 2 programmers

понедельничек

regarding Scala types

а вот немножко логики

how to hire, a tutorial

munit

strange scala code

just figured

монокль

Jon Pretty on Fury at ScalaBay

here's the Https Server I wrote

с ужасом обнаружил...

SF Scala Video Channel

пара заметок

about tagless-final

I recommend this book

come listen to my talk on topos logic implementation

seems like a compiler bug

ok, done with Lawvere-Tierney topologies

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