Despite having read "Programming in Scala" several times, I still often finds important Scala constructs that were not explained in the book, like
#uncheckedVariance
#specialized
and other strange constructs like
new { ... } // No class name!
and so on.
I find this rather frustrating, considering that the book was written by the Scala "inventor" himself, and others.
I tried to read the language specification, but it's made for academics, rather than practicing programmers. It made my head spin.
Is there a website for "Everything "Programming in Scala" Didn't Tell You" ?
There was the daily-scala Blog, but it died over a year ago.
Currently, we're working on a central documentation site for scala-lang.org. We're hoping that this solves a lot of the documentation issues that new users face. More details on this effort can be found at http://heather.miller.am/blog/2011/07/improving-scala-documentation/, but in summary...
Believe it or not, there are a lot of documents that the Scala team has produced but which simply aren't in HTML or are otherwise difficult to find. Such as Martin's new Collections API, his document on Arrays, or Adriaan's on Type Constructor Inference.
One goal of such a site is to collect all of this documentation in one place, in a searchable, organized, and easy-to-navigate format.
Another goal is to collect excellent community documentation out there, and to put it in the same place as well. For that, we are actively looking for quality (article/overview-like) material with maintainers. Examples include the Scala Style Guide, and Daniel Spiewak's Scala for Java Refugees.
Yet another goal is to make it easy for contributors to participate- so the site is built from RST source, which will live in a documentation-only github repo at https://github.com/scala/scala-docs.
So, in short, something better is on it's way, and contributors are very welcome to participate.
EDIT: http://docs.scala-lang.org is now live.
Several documents considered to be rather detailed or even obscure are already available. This includes all "Scala Improvement Proposals" (the proposals produced when new language features are suggested, and which are usually very detailed, and written by the implementers themselves). Also available is the entire glossary from Programming in Scala, Scala cheatsheets, amongst many other documents. The bottom-line of the site is to be community-focused and contribution-friendly-- so, free, and totally open. Suggested topics to cover are also welcome.
Take a look at scalaz and typelevel librairies (shapeless, spire, etc.), they rely on many advanced features of Scala.
*scalaz was for a time part of typelevel, but it is no more the case.
Josh Sureth's book goes a little beyond the usual. It's not as far as I'd like but I'm not his core audience - still, there's a lot of good stuff in there.
http://www.manning.com/suereth
Scala IRC: irc://irc.freenode.net/scala
Scala forum: http://scala-forum.org/
Blogs: Just look at http://planetscala.com/
Programming Scala (Wampler, Payne): http://ofps.oreilly.com/titles/9780596155957/
Programming in Scala (Odersky, Venners, Spoon) - good but Scala 2.8: http://www.artima.com/pins1ed/
The new documentation page is online:
http://docs.scala-lang.org/
I've kept a library of advanced Scala resources, primarily talks and blog posts. It's updated pretty regularly as I find new, interesting content.
Happy to add new links to it if anyone has recommendations.
Try to read SBT Source: https://github.com/harrah/xsbt/wiki
Its a good exercise. Also check out the book 'scala in depth' : http://www.manning.com/suereth/ by
Joshua D. Suereth
I believe there are a lot of good answer here. But as a sharing of experience. I have been coding Scala for 2 year (not my full time job), and been progressively better at it. My project is 97% Scala, and I have been able to do most of it with:
Programming Scala
The scala-user list
Stackoverflow
This cover most of the need for the "user" side of Scala, meaning all you need to create working application. However if you want to write some more complex code, or create powerful typed libraries you definitely need more.
If you want to go beyond the basics and are prepared to delve deeply into type system, and libraries, then the alternatives I use:
Use the community, scala enthusiast are really nice. I have worked with folks form Specs, Scalaz and Lift.
IRC is really good and some of the core contributors to some of the big library frequently show up.
Jump to source code, but don't try to understand everything. Scala type system can be daunting, however you normally don't need to understand 100% of it to use it.
If you really need to get into the nitty gritty details, hit the language specs, development list, and get to know the key people.
However you can really be very effective in Scala without needing to understand every single bit of the language.
Related
I want to learn Lift. Unfortunately, all documentation which I tried either obsolete, unreadable, incorrect or combination of the above. I tried the following:
Simlply Lift. Some things from the book I tried lead to errors.
Exploring Lift. The structure of book is very bad. It's hard to read and try out code in the wild at the same time.
Lift in Action. The same as the previous but you need to pay for it.
P.S. I've seen similar questions. Most of them were asked a long time ago. Did the situation improve from the time of that writings?
P.P.S. Are there any other type safe scala web frameworks (Don't offer Play 2.0. It's not typesafe. I don't see any reason to create it in Scala).
It is unfortunately true that the state of Lift documentation is uneven at best and there are huge gaping holes.
However, the Lift community is just full of awesomely helpful people.
My recommendation is not to play around, but rather to try and implement something. If you get stuck, ask specific, direct questions about what you're trying to do, how you're doing it and why it isn't working.
So far, though I would wish for better documentation, I've been able to get every answer that I needed either through Google or on the Lift mailing list - though I expect I might ask more questions here in the future.
The Lift documentation is not its strong point. The philosophy is more "try and ask if you have any problem". Here are a few tips:
Assembla
One ressource that is really useful is http://www.assembla.com/wiki/show/liftweb, there are a lots of examples so you can progressively learn how it works.
Mailing List
Otherwise you can always use the mailing list if you have specific questions even if in my opinion it is really hard to explore it fast in order to solve a problem which was already encountered. http://groups.google.com/group/liftweb
Stack Overflow
Finally, a small community is present on Stackoverflow so feel free to ask in here. This is a good way of looking for answers and creating documentation in the same time.
Source code
Don't hesitate to explore the source code and the scaladoc if you have specific questions/doubts about the behavior of a function, they are often short and even sometimes commented! http://scala-tools.org/mvnsites/liftweb-2.4-M4/#package
Have a look at the Lift Cookbook: http://cookbook.liftweb.net/
"Simlply Lift. Some things from the book I tried lead to errors."
What exact type of errors did you have? Have you tried to follow it with "Simply Lift" examples that you can download from GitHub
https://github.com/dpp/simply_lift?
Only errors I had were related to my lack of experience with SBT, but that's another story.
I have started with Lift mostly from that source (Simply Lift + examples) and in combination with its great community and Google (ChrisJamesC has listed the main links really nice) it was quite okay for me.
I would suggest you to work out all examples given in the "Simply Lift" tutorial or at least work them out unless you feel comfortable enough to jump right "in media res" and try something by yourself. That was the best way of learning Lift for me.
Also, whenever you got stuck somewhere and can't find solution on the web, your questions would be welcome and answered on the Lift Google Group (https://groups.google.com/forum/?fromgroups=#!forum/liftweb). David Pollak is very often right there to answer your questions directly so I have only words of praise for this framework's community and Lift's
creator.
P.S. Lift's documentation could be better organized, some stuff could be better explained for sure, but IMHO it was just too small a price I had to pay to enjoy such beautiful framework. Learning curve is steeper than with Play, especially in the beginning, but after I "survived" the very first week it was almost impossible for me to give up of all of its advantages and original concepts (Lift's "Seven Things") and switch to another framework.
What are some good online articles or videos you've seen that would be most likely to get a developer interested in Scala? I'm looking for an introduction that is brief & to the point that dives right into example code, and would leave a developer who does not know Scala wanting to learn more about it.
Try in this order:
Pragmatic Real-World Scala - This video shows off all kinds of things that would make a Java developer drool.
Programming In Scala - This is simply a great general-purpose programming book. In addition to being a gentle, clear introduction to the language, it's also a fantastic introduction to functional programming concepts and language design. Even if you hate Scala,
this book will make you a better programmer.
Scala For Java Refugees - Very well-written mostly gentle introduction to major Scala concepts.
Another tour of Scala - A Java-centric breakdown of fundamental Scala features.
i went to this talk, it was excellent. can't tell if it is still there due to our internet restrictions, if it's not i'll delete this post.
http://powerhost.powerstream.net/008/00102/100203Scala.wmv
I'd go straight to the horse's mouth, the Scala website itself: Code Examples.
http://www.escalatesoft.com/screencasts
Escalate software is in the process of creating a series of screencasts for Scala information sharing and training purposes. The first available screencasts are provided here for free and cover the new features of Scala 2.8. In the longer term we will create training materials in the form of these videos along with supporting material that will be for sale from this and other sources as well.
http://blog.jaoo.dk/2009/03/09/an-introduction-to-the-scala-programming-language-by-bill-venners/
Take a look at the following presentation by Jonas Bonér (a well known figure in the Scala community, responsible for the AKKA actors concurrency framework). I'm sure this will whet the appetite for Scala.
http://www.infoq.com/presentations/Scala-Jonas-Boner
german introduction, maybe useful for you: http://www.rheinjug.de/videos/gse.lectures.app/Player.html#Scala
I would recommend Chapter 1. Zero to Sixty: Introducing Scala of the Programming Scala book by Dean Wampler and Alex Payne. The rest of the book is also great. The book is freely available online.
EDIT
I recently bought and read the Atomic Scala book by Bruce Eckel and Dianne Marsh. This is the best book I have read so far for anyone wanting to learn Scala.
Now i know that this one is actually not a very technical question but one that has been bothering me for some time. Actually we are using a lot of C++ and PHP at our company and some of our developers are really hoping for a new and modern language to come by to help us getting more productive. I have been talking about what scala can do and the other coders seem to gain some interest in the language. The tough job is, how do you convince your boss to consider scala as a language for the company. I saw the presentation "Sneaking Scala into your company", but it deals with the situation that you are using Java at your company which we don't.
How do you fight of the usual "that is just esoteric stuff" and "we can already do that in $LANGUAGE" arguments. I was planing to give a talk about Scala, and since I don't have much time I need ideas how to get people interested in the language rather then setting of reactions like "currying? we can already do something like this with boost::bind".
How did you guys do it?
Regards,
raichoo
EDIT: Gave my talk yesterday, people were very excited. My company is going to give it a try! Thanks for all your suggestions.
If you don't already have killer arguments, what are you basing your reasoning on that Scala will make your company more productive?
Don't like something then hunt for reasons to use it at work. Let the reasons speak for themselves..
"A hammer looking for nails"
Using it to do some stuff around the side, as datamigrations, testing and similar things will make sure the necessary experience is built and can give it some exposure.
ScalaTest is really nice to help with acceptance/integration testing. (Yes, I know it is nice for unit testing, but I do not see that immediately happening with C++/PHP target code, and it would probably be unwise).
Proof of Concept and other Prototypes are great for 2 reasons
1) It showcases the capabilities
2) You are certain they will be thrown away if you have to reimplement them in C++/PHP
Now a bad time to introduce Scala would be when you REALLY need it : hopes will be high, it will not immediately work as intended, hopes are dashed and everybody will blame Scala. As a result it will be burnt for a long time in the organisation.
Sooner or later some suit will think it was his idea to introduce Scala and use it on a formal project. If that project is moderately successful, then it is sold.
These kind of changes are complicated people issues, and the harder you push, the harder you will face push-back. On the other hand the persistent mind can move mountains.
Redo some of your work related code in Scala and compare KLOC, code structure and performence, if it looks and works better, show it to your peers and your managers.
In other words:
Talk is cheap. Show me the code.
-- Torvalds, Linus (2000-08-25)
In case of our company (and I assume, many companies share the same scenario), move to Scala (from Java) was initiated by tech people, who 1. wanted to work more productive writing code (living in the 21st century utilize modern approaches), 2. have less troubles building concurrent applications (Actors concept promoted by Scala is a way simpler than Java thread-based concurrency) 2.1 have a simpler way of building scalable staged event driven architectures.
In our company, transition to Scala was more or less simple, because Scala was literlly sold to business people as a library to Java :) -> from their POV, we're still using the same platform (JVM), application servers, etc., but developers are having more fun from their work, and therefore, are more inspired and work more efficiently.
Maybe you could pitch Scala by showing off the suite of tools that is used for development? For example, if you are not already using Eclipse in your company, show your execs a demo of what a modern IDE can do for your productivity.
There is a book called "Fearless Change" (Linda Rising) that describes a pattern language for "powerless leaders" (I LOVE that role title!). SE-radio had a really motivating interview with the author: http://www.se-radio.net/podcast/2009-06/episode-139-fearless-change-linda-rising. Listen up on that interview to collect a few non-technical strategies that can help you in this struggle!
I haven't used Scala yet for any real business code, but I know people who have.
One group used it to write a tool to analyze log files. So they didn't use it for mission-critical business code, but for a non-critical tool to support the project.
Another person I know is an architect and he just went and wrote some Scala code on his own for some production code without telling his manager. After the code was deployed successfully he did tell it. One of the things he mentioned is that because Scala runs on the JVM, the people who support the application don't even notice - to them, Scala is just another library that's included with the application (they were already used to the JVM). Ofcourse this approach is risky and not everybody will be in the position or be willing to do this.
You could start small - use it as your personal preferred scripting language for small things that you need yourself. Tell your fellow developers about it and make them enthusiasts too. If they also start using it then you can step it up to make some side code for your project (such as for example that log analyser tool).
This isn't a really easy task. I would concentrate on the fact that you will be able to produce code and therefore products faster and with a higher quality. That's always the two reasons, business wants to hear from you and will listen to.
Maybe you can show an example of 1-2 very small projects you did in your company with C++/PHP and compare the effort, quality etc. with a similar/the same implemenation in Scala? This would be very impressive and should also convince people who are not on the coding side.
There was a very good talk at Scala Days 2010 by David Copeland:
Sneaking Scala into your organisation
The executive summary: Testing. You can use Scala for testing without affecting release code.
we are considering Scala for a new Project within our company. We have some Junior Programmers with only PHP knowledge, and we are in doubt that they can handle Scala. What are your opinions? Some say: "Scala is a complicated beast!", some say: "It's easy once you got it." Maybe someone has real-world experience?
"My coworkers will not understand Scala" is simultaneously overstating its difficulty and insulting your coworkers.
Scala is not that difficult. It's just another programming language. Any trouble that junior programmers have with Scala is going to be more or less the same trouble they would have with any other language.
Your coworkers are smart. Of course, I don't know them, but it's a pretty safe bet unless your company is the kind of organisation that hires stupid people, in which case, you have bigger problems.
That said, at my company we have some core products developed in Scala, and we don't find that people have any more trouble with it than Java. The code is generally more clear and concise, easier to generalise and reuse, etc.
I guess Scala could be used as a "beginners" language. Even though there are tricky ideas behind it, you dont have to use/explain them in the beginning. If you explain pure OO with Scala, I would say it is straight forward and easily understandable. As Scala reduces a lot of code overhead from other languages it might even be easier to learn concepts with Scala than with Java/C++.
A major drawback I see with Scala as a beginner language is the lack of documentation. Don't get this wrong, the official Scala doc is very good and also the few books that are available are quite useful to get the details of the language, but those have not been written for beginners. For example in Java you find hundreds of books titled something like "Learning OO with Java" you wont find that for Scala which may be a show stopper.
As Hannes mentioned, only do new language introductions within research projects and not productive or even flagship projects. If you have some juniors, that makes the situation even better, take some internal tool, you always wanted and needed and let them create it during a research project. This is also a nice opportunity to experiment with different development-processes. And your juniors most probably like to be challenged and will deliver a good prototype and a very well proofed opinion if Scala can be used as a beginner language.
I believe that most people moving to Scala are experienced and enthusiastic coders. I'd suggest that you get in-house experience with a Scala project with your senior programmers first before forming a strategy for mentoring your junior coders. I'd also suggest that you only involve people who are eager to join in.
I would advocate it. But with the proviso that you have clear guidelines on what language features are acceptable for your team. For example, coding primarily in an imperative style (which is familiar for Java-trained people), or perhaps limiting the employment of recursion or closures.
Also plan for seniors to mentor the juniors. This may take the form of any combination of: pair programming, code reviews, info sessions, regular discussion forums, etc.
The opportunity that scala presents for vastly improved coding on the JVM is too great to pass up. When your seniors get into it I would not be surprised if they find renewed passion for development. When your juniors get into it they will be learning best practice JVM development from the start.
If you choose to go this route, perhaps they'll find easier to use the Scalate framework than a more traditional one like Lift, since it allows mixing HTML with Scala, much in the same way as PHP works.
Scala is a very 'normal' programming language. Any programmer should be able to learn this language. The people that have difficulties learning Scala mostly are experienced with imperative languages and are surprised by the functional concepts. So unexperienced programmers may learn it even faster. In my opinion should be no problem, to assign it to juniors. From a management point of view, I would assign a junior and a senior developer as a team (or more of both, depending on the size of the project).
I think it depends whats more importent for you. If you want to learn as possible about OO Programming and the standard stuff its a bad idea.
But what you really give them is a opportunity to learn something really cool and unique. Witch can be good motivation. Scala has many cool stuff in it. If you can handle Scala you can handle a lot of otherstuff as well.
Talk to the Programmers (all of them) and tell them why you wanne to use scala. Ask if the have to motivation to make and learn something not everybody can do and go the extra mile?
If the are go with it!
My initial thought would be that Scala will be too heavy for them but then I guess because Scala is an OO/Imperitave/Functional hybrid, one could introduce them to the OO/Imperative part of scala until their comfortable, but then again they will probably have bad PHP habits in Scala since scala authors mostly prefer the functional style over the imperative one.
So, it could work, but I would do it for a research project, and definately not for a flagship one.
Edit: Perhaps this should be said also: It seems that functional/OO hybrids like Scala is becoming more popular especially because of how functional languages handles parallel processing as opposed to how we know it in languages like in Java. The amount of cores found in a chip is increasing rapidly, so this is important. However, mentioning PHP, it seems that you are developing web server scripts where threading is less important. PHP doesn't even have threads.
This raises another point. Do you want to develop Scala Web applications i.e. Lift. If so then you have a doubled up learning curve which should also be considered.
Imagine that you would have picked Java and asked whether they could handle Java. If your answer is they could, then they can probably handle Scala.
Scala is only marginally more difficult due to:
No great IDE support. The support ranges from poor to good. Not necessarily an issue for a PHP programmer.
Documentation not as rich as Java
Both Java and Scala have new challenges for a PHP programmer (JVM, new libraries, compiled language, statically typed).
I don't think Scala is a complicated beast, but you do need to understand some of the syntactic sugar and design principles, which would be true of learning Java as well.
Yes, if...
Strategic decision has been made to go with Scala
Company can handle the hit (financial and time) that will come from the steep learning curve.
No, if...
No senior Java, C# or C++ programmers can be put on the project too
Can't find a Scala programmer to act as a lead
Programmers don't have the patience to learn Scala or deal with a language where Jars (libraries) are scattered all over the place, rather than in one or two neat packages like PHP.
*Note: if the junior programmers were C++, C#, or Java Software Engineers rather than PHP, then my answer would be different like, Go for it!
I would not recommend it. My experience of Scala is only from homebrew projects, but I would imagine the currently lousy IDE support, quite frequent API changes and a very flexible syntax (that allows one to hang himself and everybody else participating in the project) would cause a lot of problems in a bigger, more official project.
Give them IntelliJ and throw 'em in the deep end.
Here is a blog post I recently stumbled upon:
http://james-iry.blogspot.com/2008/07/java-is-too-academic.html
It shows that even Java can be too academic to be understood by programmers which have no experience in functional programming. On the other hand, Scala allows to write code the "imperative way", so you can avoid all the FP stuff if you do not understand it. In my opinion, Scala is much more concise than Java, so I guess a "junior programmer" should be able to handle it.
I've been asked to run a workshop and coding dojo soon for people to try out Scala and try to build something with it. The attendees are all going to be new to Scala, and could come from any of a number of languages (I'm presuming they can code in at least one mainstream language - I'm including syntax comparisons with Java, C#, Python and Ruby).
Part of the appeal of Scala is that it's practical - you can use it as a drop-in "power Java" (Java with less syntactical clutter, closures, immutability, FP, traits, singleton objects, nifty XML handling, type inference etc.) that still runs on the JVM (and on the .NET CLR supposedly) and doesn't require you to change build tools, server infrastructure, libraries, IDEs and so on. Most of the katas I've seen have been fun but not 'real world' - mathematical challenges like Project Euler and so on. These don't seem appropriate as we're trying to explore the use of it as a practical, real world language that people could consider using for both hacking and work, and because people aren't necessarily going to be too familiar with either the deeper parts of the Scala syntax or necessarily of the concepts behind functional programming.
So, has anyone come across any more practical, everyday katas rather than arithmetical 'problem solving' ones? Katas, that is, that can test whether the language, libraries and tools can satisfy the use cases of the actual day-to-day programming most people have to do rather than testing out. (Not that the impractical ones aren't fun, but just not appropriate for the kind of thing I've been asked to run.)
If I can't find good examples, I'm thinking that it might be useful to try and build something like a library catalogue - the event is for programmers who primarily work on building infrastructure for universities (and in education and culture - museums, galleries, schools, libraries and so on). It's a bit boring though, but it's the sort of thing that the attendees work on in their day-to-day existence. Any suggestions?
There is a creative commons licensed introductory training course with hands-on exercises here:
http://github.com/javaBin/scala-training-slides
http://github.com/javaBin/scala-training-code
The slides are in Open Office format. If you don't have this installed, you can upload them to SlideShare, which will convert them for online viewing.
Most of the programming examples in my blog are, effectively, coding dojo exercises. Particularly the matrices series, but also the puzzles and 99 beers. Now, don't disregard the matrices series as being "mathematical", because the problems I concern myself in it are related to the construction of classes in Scala, not to doing fancy algorithms. In fact, I pretty much skip over the mathematical algorithms themselves.
Now, 99 Scala Problems and pretty much everything from Project Euler are nice exercises for the functional part of Scala, but I understand that not to be your emphasis. I do recommend retronym's answer. Rosetta Code, not being functionally oriented, might have more general examples. There are many with Scala examples, of course, though you may wish to consider other tasks as well, for ideas.
There's lot of cool things to learn about Scala, but one has to be careful at beginner level. For instance, I would not speak of dependency injection (self types and the cake pattern) or of type classes (the pattern that simulates such with implicits).
Do look as well at the material on the Scala Lang site, particularly the Scala by Example document.
EDIT
I have now overseen several Scala dojos, so here's a bit of stuff I've learned from then:
Problems: they have to be fun, not-quite-easy, not-that-hard, and that has to be everyone's opinion.
We use the Dojo Puzzles site, which is in Portuguese so it won't be of use for most people here. If there's a similar site in English, I'd love to hear about it.
The way it works is you ask for a random problem, look it over and discuss to see if you'll pick it up or not, and then indicate by saying you'll use it, you'll not use it, or maybe you'll use it but you'd like to see another one. This vote gets registered and you can see how many people picked up a problem, which helps deciding whether to pick it up or not in first place.
Scala knowledge: it turns out it's not that important to introduce key concepts of Scala language beforehand, particularly if some of the participants have basic knowledge.
In my experience, setting up the testing environment with a trivial "pass" test and explaining how people should write the tests is often enough to get people started. If you feel someone is struggling to write something, give a quick explanation and get on with it.
Teaching Scala: if you do set out to teach Scala, keep lessons short and follow up with a dojo. In this case, keep a set of dojo problems that are adequate to the lesson, and, depending on how many lessons you want in one day, short.
It helps imposing artificial constraints on how one must solve a problem. Some examples of constraints I have put in practice are no classes and single-expression methods (that is, no multiple statements or val/var declarations). The point of these constraints is making it impossible for people to solve the problem in the way they are used to, which gets them to explore the language in search of alternatives.
I have the final results of three dojos done at my current job in this repository.
At the moment we are using the Randori Kata format, but without fixed time or break, and with retrospective at the end of the dojo, not at the beginning of the next. This, however, is just were we are currently at -- we have experimented many variations, and we are still evolving.
Perhaps you could have a look at the Ruby Quiz material for inspiration.
Take a look at Scala by example from Martin Odersky (creator of scala)