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A Major Datomic Update

The latest release of Datomic includes some additive new features to enable more architectural flexibility for our customers, especially those building microservices platforms and projects.  With the advent of the new Client API, users have much more choice when it comes to their deployment topology.  I am also very pleased to announce the new simplified pricing model: Starter for explorers, Pro for production use, and Enterprise for customized licensing/support.  Customers at each level will now have access to identical features, including unrestricted Peer counts per Transactor.  For more, see the official announcement.

Works on My Machine: How We Work: Distributed

Working for a distributed company -- Cognitect is scattered across much of the United States and Europe -- does have its ups and downs. I love not having to commute. But I miss hanging out with my coworkers, live and in person. I love that my office is just upstairs, in that spare bedroom. But sometimes I wish I could put more distance between my job and the rest of my life.  I love that the Internet lets me talk to just about anyone, anywhere. And sometimes I wish I could throw my computer, complete with its bogged-down network connection out the window.

Working for a distributed company also means that I get asked "the question" a fair bit. Actually the question is really a family of questions: "What's it like?" is a common variation. So is "Isn't it hard to get things done?" Then there is "What skills do I need to work remotely?" and, of course "How do I talk my boss -- or potential boss -- into this?"

Interactive Development with Clojure.spec

clojure.spec provides seamless integration with clojure.test.check's generators. Write a spec, get a functioning generator, and you can use that generator in a REPL as you're developing, or in a generative test.

To explore this, we'll use clojure.spec to specify a scoring function for Codebreaker, a game based on an old game called Bulls and Cows, a predecessor to the board game, Mastermind. You might recognize this exercise if you've read The RSpec Book, however this will be a bit different.

Agility & Robustness: Clojure spec

You can program with high agility and end up with a robust, maintainable program. This talk will show you how to use Clojure and the new spec library to write programs that behave as expected, meet operational requirements, and have the flexibility to accommodate change.

Works On My Machine: Understanding Var Bindings and Roots

When designing applications and systems it can be important to understand the inner workings of certain aspects of the language being used by developers. One area of Clojure that is traditionally rather opaque and poorly understood is the inner workings of Vars, and how they interact with the Clojure Language. I recently encountered some behavior that seemed puzzling:

Focus on spec: Combining specs with s/or

In our last post, we looked at `s/and`, a way to combine multiple specs into a compound spec. It should come as no surprise that spec also provides `s/or` to represent a spec made of two or more alternatives. 

Focus on spec: Combining Specs with `and`

Clojure's new spec library provides the means to specify the structure of data and functions that take and return data. In this series, we'll take one Clojure spec feature at a time and examine it in more detail than you can find in the spec guide.

In our last post, we explored the simplest specs: predicate functions and sets. In this post we'll look at how you can start to combine specs using the and spec.

The New Normal: Tempo, Flow, and Maneuverability

Tempo. Most people are familiar with it in the musical sense. It’s the speed, cadence, rhythm that the music is played. It drives the music forward - and pulls it back.

But there’s more to tempo than a musical beat. In life, as author Venkatesh Rao described in his book, “Tempo,” it makes for some of the most memorable moments as it shifts faster or slower. In war, like in business, tempo - the speed at which you can transition from one task to the next - is a critical component for victory.

Welcome to

We are happy to announce that ClojureScript now has an official web site at! Most of the content from the ClojureScript wiki has been migrated into the new site and organized. 

The site design was carried over from the Clojure web site - thanks to Tom Hickey for the design on the original site. We have adopted the community CLJS logo as the official logo for ClojureScript - many thanks to the designers Chris Oakman and Brett Darnell. 

The new site content is hosted in a GitHub repository and is open for contributions. All contributions require a signed Clojure Contributor Agreement. This repository will accept contributions via pull request and issues with GitHub issues. The contribution and review process is described in more detail on the site contribution page.

This site is a starting point. Because most of the content originated in the wiki, it's likely to need updates in a number of places. There are also many places that content can be added in the Reference, Tools, Guides, and Community sections. We welcome your contributions and thank you for being part of the ClojureScript community! If you have questions, please file an issue on the site repo or contact us on the mailing lists, Slack, IRC, etc for discussion.

We look forward to seeing the site grow!

The New Normal: Mean Time To Reaction

Slime mold can teach you everything you need to know about being an agile, adaptive and responsive company.

OK, maybe not everything, but there are some valuable lessons to take away. That oozing organism can quickly sense, decide and act in response to changes in its environment.  It is no more than a group of amoebae encased in slime, yet they exhibit behaviors that are comparable to those of animals who possess muscles and nerves – that is, simple brains.

Clojure spec Screencast: Customizing Generators

One benefit of Clojure specs is that they automatically provide data generators that produce values conforming to the spec which can be used for testing. In addition, you can compose your own generator to more precisely match your data model.

Focus on spec: Predicates

Clojure's new spec library provides the means to specify the structure of data and functions that take and return data. All specs definitions are ultimately based on predicates, which are nothing more than Clojure functions that take a value and return a value that is treated as logically true or false.

Clojure spec Screencast: Testing

Clojure spec defines specifications for both data and functions. In addition to validity checking, specs can generate random samples of the data they specify. This capability enables an alternative to unit testing known as generative, or property-based, testing.

Clojure spec Screencast: Leverage

The new Clojure spec library provides support for data and function specification. In this first in a series of screencasts, Stuart Halloway discusses how spec provides leverage to achieve many returns for a small investment in describing your functions with spec.

The New Normal: Failure Domains and Safety

Through this series, we've talked about antifragility, disposable code, high leverage, and team-scale autonomy. Earlier, we looked at the benefits of team-scale autonomy: It breaks dependencies between teams, allowing the average speed of the whole organization to increase. People on the teams will be more fulfilled and productive, too. These are nice benefits you can expect from this style, but it's not all unicorns and rainbows. There is some very real, very hard work that has to be done to get there. It should already be clear that you must challenge assumptions about architecture and development processes. But we also need to talk about critical issues of failure domains and safety.

The New Normal: Data Leverage

Like many developers, I’ve spent a lot of time thinking about objects. I started doing object-oriented programming (OOP) in 1989, and was arguably still doing it up until 2012. The concept of objects arose in GUIs and simulations, where it is natural to think about sending message to things. Over time though, the idea of messages took a back seat to the idea of locking data up in little containers where each class provides a namespace of functions to operate on it.

The New Normal: Team Scale Autonomy

You’re probably familiar with the concept of the two pizza team. This is Amazon founder and CEO Jeff Bezos’ rule that every team should be sized no bigger than you can feed with two large pizzas. At Cognitect, we take this concept one step further: the one chateaubriand team—with sharper tools you can afford to spend the extra money on better food.

The two pizza team is an important concept. The idea is that smaller teams are more self-sufficient and typically have better communication and a greater focus on getting things done because they eliminate dependencies. Every dependency is like one of the Lilliputian ropes that ties Gulliver to the beach. Each one may be simple to deal with on its own, but the collection of 1,000 tiny threads keeps you from breaking free. Eliminate dependencies and your teams move faster. Encourage autonomy and you allow innovation.

Happy 100th!

Cognitect hit a pretty impressive milestone this week that deserves some celebration - we released our 100th Cognicast (the Cognitect podcast for those of you not yet in the know).  As our esteemed host Craig Andera likes to say, he "just decided to do it one day, and we have so far failed to stop."  But I think that shortchanges the quality of what's come out of it. 

The New Normal: Everything Relies on Sharp Tools

You wouldn’t use a toothpick to wear down a mountain. You wouldn’t wear your trainers instead of your racing spikes at a track meet. So why would you use a hand saw to build an infrastructure when you need a scalpel for surgical precision?

Up to this point in the series, we’ve talked about embracing failure, experimenting more and moving faster. We've talked about the "why," now it's time to address the "how."