Using syntax/loc and unit test macros

:: Racket, macros

In my previous post, I wrote about a nuance with syntax/loc, using the example of a macro that both defines and provides a function. But why don’t I back up, and look at a simpler example of why you’d want to use syntax/loc. The example is a simple macro you might often find yourself wanting, to reduce the tedium of writing unit test cases.

Using syntax/loc

:: Racket, macros

There’s a nuance to syntax/loc. The documentation says, emphasis mine:

Like syntax, except that the immediate resulting syntax object takes its source-location information from the result of stx-expr (which must produce a syntax object), unless the template is just a pattern variable, or both the source and position of stx-expr are #f.

What does “immediate” mean here?

Racket package management

:: Racket

Racket’s new package manager is great. It debuted with Racket 5.3.5. Although officially still in beta, it was already good enough to use for real projects. Racket developers wanted people to use it for real projects, to get the experience needed to make it even better.

Over many months, the Git HEAD version of Racket — what would become Racket 6 — gradually introduced a few new and changed features for package management.

However, you might not want to use the newer features, yet. Not if you want your package to be usable by people still using Racket 5.3.5 or 5.3.6 — or usable by other packages that wish to support such people.

Fortunately, the older features are still supported in Racket 6, and it’s not very difficult or inconvenient to use them. You just need to know what they are.

Interview and RacketCon talk

:: software

I haven’t posted here in awhile because I’ve been busy with a variety of things in September, including an interview for IEEE Computer magazine and a talk about Frog at RacketCon. And I’m writing this in Japan.

Using call/input-url

:: Racket

When I learned Racket, one of the first things I wanted to try was doing HTTP requests. And Racket’s net/url module is great.

Racket was the first real Lisp/Scheme family language I ever learned. As a result I was focused on building blocks like ports, and assuming I would need to open and close them directly all the time. At that early stage, I also didn’t really appreciate the value of higher-order functions. So I overlooked the value of call/input-url. I sometimes see other folks do the same, and wanted to write this short blog post.

Spoiler Alert: Just Give Google Power of Attorney

:: Google, technology

Robert Scoble’s “Google, the freaky line and why Moto X is a game-changer” describes the significance of its always-on voice recognition. Under the heading, “the joy of context”:

Moto X is just one in a string of products and services that will bring radical new functionality to users. Examples? Google Now, Google Glass, and the new Moto X phone that keeps the microphone open full-time. The Xbox One, coming this winter, will have a 3D sensor on it so sensitive it can see how fast your heart is beating just by watching your skin.

These new contextual, sensor-based features are game changers and I’m hearing Google has a raft of other product announcements lined up that will turn on even more freaky features. Why? Because the more Google can get you to communicate with your phone, the more context it can slurp up.

The more sensors it can turn on, or put on you, the more it can learn about your intent and your context. Today your phone doesn’t really know that you’re walking, running, skiing, shopping, driving, or biking, but in the future, Google will know that and will be able to build wild new kinds of systems that can serve you when doing each of those things.

Naturally people have a variety of reactions for different reasons. You may find it yawningly predictable, or alarmingly freaky, or something in between. You might not mind Google slurping your data because you gave consent, but be creeped out by NSA contractors wrapping their lips around it uninvited.

But at bottom what’s the motivation behind this push for “context” and “intent”?

Skim or sink

:: software, Racket

In my experience, the way to become a better programmer is to:

  • write lots of code
  • skim lots of reading material, and
  • defer answers until you have questions.

To learn why you should skim this post, please read it carefully.

Using Travis CI for Racket projects

:: Racket

Travis CI is a continuous integration service for open source projects that has nice integration with GitHub.

Whenever you push a commit to GitHub, a build/test can launch. Notification of the result comes via a variety of methods. Also there’s a “badge” to show the build status, which you can link to in your README.md.