cranst0n

Fibers

Fibers are an abstraction over sequential computation, similar to threads but at a higher level. There are two ways to think about this model: by example, and abstractly from first principles. We'll start with the example.

(credit here is very much due to Fabio Labella, who's incredible Scala World talk describes these ideas far better than I can)

Callback Sequentialization

Consider the following three functions

Quick PSA on Metals with vscode

Since scala changes a lot of files in build and vscode watches those files. It actually has quite a delay. Adding this to settings will improve performance by an enormous degree. Especially on larger projects.

"files.exclude": {
        "**/.bloop": true,
        "**/.metals": true,
 "**/target": true

Concurrent resource caching for cats

Motivation

cats-effect Resource is extremely handy for managing the lifecycle of stateful resources, for example database or queue connections. It gives a main interface of:

trait Resource[F[_], A] {
  /** - Acquire resource
    * - Run f
 * - guarantee that if acquire ran, release will run, even if `use` is cancelled or `f` fails

introduction

ScalaCheck 1.14.0 was just released with support for deterministic testing using seeds. Some folks have asked for examples, so I wanted to produce a Gist to help people use this feature.

simple example

These examples will assume the following imports:

How to GPG as a Scala OSS Maintainer

tl;dr Generate a GPG key pair (exercising appropriate paranoia). Send it to key servers. Create a Keybase account with the public part of that key. Use your keypair to sign git tags and SBT artifacts.

GPG is probably one of the least understood day-to-day pieces of software in the modern developer's toolshed. It's certainly the least understood of the important pieces of software (literally no one cares that you can't remember grep's regex variant), and this is a testament to the mightily terrible user interface it exposes to its otherwise extremely simple functionality. It's almost like cryptographers think that part of the security comes from the fact that bad guys can't figure it out any more than the good guys can.

Anyway, GPG is important for open source in particular because of one specific feature of public/private key cryptography: signing. Any published software should be signed by the developer (or company) who published it. Ideally, consu

	# Create Nexus Proxy Reposity with Remote Storage = https://index.crates.io
	# .cargo/config.toml should be placed accoding docs https://doc.rust-lang.org/cargo/reference/config.html

	[registries.nexus]
	index = "sparse+https://nexus.app/repository/cargo/"

	[registry]
	default = "nexus"

	[source.crates-io]

	// scalaVersion := "3.2.0"
	// libraryDependencies ++= Seq(
	// libraryDependencies ++= Seq(
	// "org.typelevel" %% "cats-core" % "2.8.0",
	// "dev.zio" %% "zio" % "2.0.0",
	// "org.typelevel" %% "cats-effect" % "3.3.14",
	// "org.typelevel" %% "kittens" % "3.0.0",
	// "dev.zio" %% "zio-json" % "0.3.0-RC10",
	// "io.d11" %% "zhttp" % "2.0.0-RC10"
	// )

	import android.os.Bundle
	import androidx.lifecycle.Lifecycle
	import androidx.lifecycle.LifecycleRegistry
	import androidx.savedstate.SavedStateRegistry
	import androidx.savedstate.SavedStateRegistryController
	import androidx.savedstate.SavedStateRegistryOwner

	internal class MyLifecycleOwner : SavedStateRegistryOwner {
	private var mLifecycleRegistry: LifecycleRegistry = LifecycleRegistry(this)
	private var mSavedStateRegistryController: SavedStateRegistryController = SavedStateRegistryController.create(this)

	import cats.Eq
	import cats.effect.{ContextShift, IO, Timer}
	import org.scalactic.Prettifier
	import org.scalactic.source.Position
	import org.scalatest.exceptions.TestFailedException
	import org.scalatest.{Assertion, AsyncTestSuite}

	import scala.concurrent.Future
	import scala.concurrent.duration._
	import scala.reflect.ClassTag

	import 'dart:math' show pi;

	import 'package:flutter/material.dart';

	/// A Widget that can be configured to show funky spinning rectangles!
	///
	/// ### Usage
	///
	/// ```
	/// Spinnies(