Gigahorse 0.2.0 is now released. The new change is that it abstracts over two backends. @alexdupre contributed migration from AHC 1.9 to AHC 2.0, which is based on Netty 4 in #12.
In addition, there’s now an experimental Akka HTTP support that I added. #15
Please see Gigahorse docs for the details.
gigahorse-github 0.1.0 is released. This is a Gigahorse plugin for Github API v3.
Update: please use Gigahorse 0.1.1
Gigahorse 0.1.0 is now released. It is an HTTP client for Scala with Async Http Client underneath. Please see Gigahorse docs for the details. Here’s an example snippet to get the feel of the library.
scala> import gigahorse._
scala> import scala.concurrent._, duration._
scala> Gigahorse.withHttp(Gigahorse.config) { http =>
val r = Gigahorse.url("http://api.duckduckgo.com").get.
addQueryString(
"q" -> "1 + 1",
"format" -> "json"
)
val f = http.run(r, Gigahorse.asString andThen {_.take(60)})
Await.result(f, 120.seconds)
}
There’s a “pattern” that I’ve been thinking about, which arises in some situation while persisting/serializing objects.
To motivate this, consider the following case class:
scala> case class User(name: String, parents: List[User])
defined class User
scala> val alice = User("Alice", Nil)
alice: User = User(Alice,List())
scala> val bob = User("Bob", alice :: Nil)
bob: User = User(Bob,List(User(Alice,List())))
scala> val charles = User("Charles", bob :: Nil)
charles: User = User(Charles,List(User(Bob,List(User(Alice,List())))))
scala> val users = List(alice, bob, charles)
users: List[User] = List(User(Alice,List()), User(Bob,List(User(Alice,List()))),
User(Charles,List(User(Bob,List(User(Alice,List()))))))
The important part is that it contains parents field, which contains a list of other users.
Now let’s say you want to turn users list of users into JSON.
This is part 3 on the topic of sjson-new. See also part 1 and part 2.
Within the sbt code base there are a few places where the persisted data is in the order of hundreds of megabytes that I suspect it becomes a performance bottleneck, especially on machines without an SSD drive. Naturally, my first instinct was to start reading up on the encoding of Google Protocol Buffers to implement my own custom binary format.
Two months ago, I wrote about sjson-new. I was working on that again over the weekend, so here’s the update. In the earlier post, I’ve introduced the family tree of JSON libraries in Scala ecosystem, the notion of backend independent, typeclass based JSON codec library. I concluded that we need some easy way of defining a custom codec for it to be usable.
In between the April post and the last weekend, there were flatMap(Oslo) 2016 and Scala Days New York 2016. Unfortunately I wasn’t able to attend flatMap, but I was able to catch Daniel Spiewak’s “Roll Your Own Shapeless” talk in New York. The full flatMap version is available on vimeo, so I recommend you check it out.
I made a new Github organization called foundweekends for people who like coding in the weekends. If you want to join, or have project ideas ping me on twitter or come talk to us on Gitter.
As the starter, it will pick up maintenance of conscript, giter8, and pamflet from @n8han.
One of the fun way of thinking about software projects is literary analysis. Instead of the actual source code, think of who wrote it when and why (what problem does it solve), and how it’s written (what influenced it). Within the Scala ecosystem, not too many genre are as rich as the JSON libraries.
In December 2008, the first edition of Programming in Scala came out, which used JSON as an example in the context of parser combinator, and showed that JSON parser can be written in 10 lines of code:
This is a continuation from the sbt 1.0 roadmap that I wrote recently. In this post, I’m going to introduce a new implementation of sbt server. Please post on sbt-dev mailing list for feedback.
The motivation for sbt server is better IDE integration.
A build is a giant, mutable, shared, state, device. It’s called disk! The build works with disk. You cannot get away from disk.
– Josh Suereth in The road to sbt 1.0 is paved with server
The disk on your machine is fundamentally a stateful thing, and sbt can execute the tasks in parallel only because it has the full control of the effects. Any time you are running both sbt and an IDE, or you’re running multiple instances of sbt against the same build, sbt cannot guarantee the state of the build.
There’s been some discussions around sbt 1.0 lately, so here is a writeup to discuss it. This document is intended to be a mid-term mission statement. A refocus to get something out. Please post on sbt-dev mailing list for feedback.
I don’t have a good idea on the timing of when sbt 1.0 will ship. The biggest feature of sbt 1.0 is code reorganization, which is is already in progress: http://www.scala-sbt.org/0.13/docs/Modularization.html
For me (and for many of the 27 organizers, I imagine) ScalaMatsuri is a lifestyle. It’s true that there was a successful two-day conference in Tokyo with 550 participants. But for us the organizers, the preparation has been going on since February 28th, for 11 months. Despite the fact that my contribution was small, planning ScalaMatsuri 2016 was by far the most amount of involvement I’ve committed to. Through the course of planning months, there were many discussions over Slack, Hangouts, and occasionally even face-to-face. The fun part was coming up with the ideas together, and seeing them materialize. Sometimes, I was the one coming up with radical ideas that were being executed by someone else, while other times, it was the opposite case and I was getting my hands dirty.
For a flexible language like Scala, it’s useful to think of subset of the programming language, like your own personal Good Parts, and opinionated style guides.
To try -Yno-lub, you can drop in the following sbt plugin to project/ynolub.sbt:
addSbtPlugin("com.eed3si9n" % "sbt-ynolub" % "0.2.0")
When Scala’s type inferencer finds type A and type B to unify, it tries to calculate the lub (least upper bounds) of two types with regards to <:<. This process is sometimes called lubbing. Here are some of the examples:
Check out my new series herding cats. (I’m writing it using Pamflet from the get go)
This is a log of me going through Cats, a functional programming library for Scala that is currently experimental and under active development.
I gave a talk at Scala Days 2015 San Francisco with Josh Suereth (@jsuereth).
I’ve been switching between Mac and Ubuntu, and between Java 6 and 7 lately. This is a memo of how to switch Java versions on both Mac and Ubuntu.
Update: Yoshida-san told me about this thing called jEnv, which does all this.
Here’s one way of loading different shell files depending on the OS:
## basic
[ -f $HOME/dotfiles/zshrc.basic ] && source $HOME/dotfiles/zshrc.basic
## aliases
[ -f $HOME/dotfiles/zshrc.alias ] && source $HOME/dotfiles/zshrc.alias
case "${OSTYPE}" in
# MacOSX
darwin*)
[ -f $HOME/dotfiles/zshrc.osx ] && source $HOME/dotfiles/zshrc.osx
;;
# Linux
linux*)
[ -f $HOME/dotfiles/zshrc.linux ] && source $HOME/dotfiles/zshrc.linux
;;
esac
## color
[ -f $HOME/dotfiles/zshrc.color ] && source $HOME/dotfiles/zshrc.color
In zshrc.osx and zshrc.linux respectively you can define environment variables for Java 6, 7, and 8. Here’s for Mac:
On my way back from Uppsala, my mind wandered to a conversation I had with a collegue about the intuition of monads, which I pretty much butchered at the time. As I was mulling this over, it dawned on me.
The above is a fractal called Sierpinski triangle, the only fractal I can remember to draw. Fractals are self-similar structure like the above triangle, in which the parts are similar to the whole (in this case exactly half the scale as parent triangle).
Monads are fractals. Given a monadic data structure, its values can be composed to form another value of the data structure. This is why it’s useful to programming, and this is why it occurrs in many situations.
Let’s look at some examples:
scala> List(List(1), List(2, 3), List(4))
res0: List[List[Int]] = List(List(1), List(2, 3), List(4))
Two days of #ScalaMatsuri ended as a huge success. But for the next year, I’m leaving ourselves a few homeworks to work on. As the title suggests, the next goal that we should aim for is universal access. In Scala language, universal access principle indicates the fact that both methods and fields can be accessed interchangeably from outside.
For a conference, I mean universal access to mean being more inclusive to various groups of people:
This year was the second Scala conference in Japan. We’ve changed the name to ScalaMatsuri, which means Scala festival in Japanese. 300 tickets sold out. With invited guests and free tickets for sponsors, there may have been even more people. The venue was at CyberAgent, which runs blog service and online ad services.
Day 1 kicked off with Martin’s (@ordersky) ‘Evolution of Scala.’ Many people were looking forward to see Martin, so I think it was full house from the get go. During all sessions that I attended, I was busy typing live text translation using my closed-captioning both from English to Japanese, and from Japanese to English along with other members @cbirchall, @cdepillabout, @okapies, and @oe_uia.
/msg NickServ REGISTER %password% youremail@example.com
What is the recommended way to set up my IRC nickname?
To check whether a channel has already been registered, use the command:
/msg ChanServ info ##channelname
/join ##channelname
The command to register your channel (once you’ve joined it and you have op status) is as follows:
/msg ChanServ register ##channelname
Personally, I don’t mind using SublimeText, which is my editor of choice for a while. But I’m also curious about commandline editors since many people taut their ability to code over the network. You could forward X or remote in using some other way and still use Sublime, but let’s see how if goes.
I started working on this Vim setup when I got a new MBP recently. Figured, I can try something new. So, this post is more of a personal memo written by a total newbie, which is what blogs are all about. caveat emptor. In general though, the configuration is mostly inspired by yuroyoro-san’s blog post from a couple years ago.
The need for regular expressions is real. Whenver I need to transform a set of text files it usually ends up with fumbling through the documentation of find command, zsh, and StackOverflow Perl questions. I would rather use Scala instead of muddling through Perl. It’s really the matter of my familiarity than anything else.
For example, I now have over a hundred reStructuredText files that I want to convert into markdown. I first tried pandoc, and it looked mostly ok. As I was going through the details, however, I noticed that many of the code literals were not converting over as formatted. This is because they were formatted using either single ticks or using Interpreted Text. Preprocessing the text with a series of regex replacements should work.
See Preview of upcoming sbt 1.0 features: Read about the new plugins posted on typesafe.com/blog.
Slides from nescala day 2 unconference:
I may have added a few more :)
Here are the slide decks and video for learning Scalaz talk:
Woke up early yesterday, so I started skimming @xuwei_k’s override blog post. The topic was so intriguing, I got out of the bed and started translating it as the curious case of putting override modifier when overriding an abstract method in Scala. In there he describes the conundrum of providing the default instances to typeclasses by using Scalaz codebase as an example.
Here’s a simplified representation of the problem:
trait Functor {
def map: String
}
trait Traverse extends Functor {
override def map: String = "meh"
}
sealed trait OneOrFunctor extends Functor {
override def map: String = "better"
}
sealed trait OneOrTraverse extends OneOrFunctor with Traverse {
}
object OneOr {
def OneOrFunctor: Functor = new OneOrFunctor {}
def OneOrTraverse: Traverse = new OneOrTraverse {}
}
To test this you can run:
This is a translation of Scalaで抽象メソッドをoverrideする際にoverride修飾子を付けるべきかどうかの是非 by Kenji Yoshida (@xuwei_k), a Scalaz committer.
First, a quote from Programming in Scala, 2nd ed. p. 192:
Scala requires [
override] modifier for all members that override a concrete member in a parent class. The modifier is optional if a member implements an abstract member with the same name.
In this post, we’ll discuss this “The modififier is optional.” Since overriding an existing method with implementation requires override modifier, and failure to do so would result to a compiler error, there’s not much to talk about for that case. We’ll focus on whether one should put override modifier or not in the case of overring an abtract method. I don’t think there’s going to be any difference in Scala version, but let’s assume the latest stable 2.10.3.
In this post, I will discuss the execution semantics and task sequencing in sbt 0.13. First we will cover the background, and then I will introduce a new experimental plugin sbt-sequential that adds sequential tasks.
Mark said:
The sbt model is to have your side effects be local to your task so that as long as dependencies are satisfied, the task can be executed whenever. The win is parallel by default and enabling faster builds in practice.
Warning: This is a memo about sbt for intermediate users.
At the heart of sbt 0.13 is the setting system, just like sbt 0.12. Let’s look at Settings.scala:
trait Init[Scope] {
...
final case class ScopedKey[T](
scope: Scope,
key: AttributeKey[T]) extends KeyedInitialize[T] {
...
}
sealed trait Initialize[T] {
def dependencies: Seq[ScopedKey[_]]
def evaluate(map: Settings[Scope]): T
...
}
sealed class Setting[T] private[Init](
val key: ScopedKey[T],
val init: Initialize[T],
val pos: SourcePosition) extends SettingsDefinition {
...
}
}
If we ignore pos for now, a setting of T consists of the lhs key whose type is ScopedKey[T], and the rhs init whose type is Initialize[T].
How do you define oop?
Purely object-oriented programming is defined to be:
programming with objects.
What’s an object?
It is an atom that can hold references to other objects, receive predefined list of messages, and send messages to other objects and itself; and nothing else. A message consists of a name and a list of reference to objects.
This is it. The wording is mine, but the idea is from Alan Kay (2003), the guy who coined the term object-oriented programming. Anything else is either not directly tied to oop or an implementation detail.
See sbt-logo proposals thread on sbt-dev and the original thread on sbt. The source is at eed3si9n/sbt-logo.
Edit: Changed the tail of ’t’. See github for the original.
.sbt build definition
sbt is a build tool for Scala and Java projects that aims to do the basics well.
sbt is a build tool for Scala and Java projects that aims to do the basics well.
.sbt build definition
sbt is a build tool for Scala and Java projects that aims to do the basics well.
sbt is a build tool for Scala and Java projects that aims to do the basics well.
.sbt build definition
sbt is a build tool for Scala and Java projects that aims to do the basics well.
sbt is a build tool for Scala and Java projects that aims to do the basics well.
