Archive for May, 2007

Episode 57: Compile-Time Metaprogramming

Filed in Episodes by on May 27, 2007 0 Comments
Episode 57: Compile-Time Metaprogramming

This episode is about compile-time metaprogramming, and specifically, about implementing DSLs via compile-time metaprogramming. Our guest, Laurence Tratt, illustrates the idea with his (research) programming language called Converge.

We started by talking about the importance of a custom syntax for DSL and took a brief look at the definition of DSLs by a chap called Paul Hudak. We then briefly covered the disctinction between internal and external DSLs.

More to the point of this episode, we discussed the concept of compile-time metaprogramming, and the language features necessary to achieve it: in converge, these concepts are called splice, quasi-quote and insertion. We then looked at how the Converge compiler works, and at the additional features that are required to implement DSLs based on the metaprogramming features mentioned above. Using an example, we then walked through how to implement a simple DSL.

Looking at some of the more technical details, we discussed the difference between the parse tree and the abstract syntax tree and at different kinds of parsers – specifically, the Earley parser used by Converge. In multi-stage languages (i.e. languages that execute programs and meta programs) error reporting is important, but non trivial. We discussed how this is done in Converge. We finally looked at how to integrate Converge’s expression language into your DSL and how to package DSL definition for later use.

The last segment look at the process of implementing a DSL in converge and about some of the history and practical experience with Converge. Lessons learned from building Converge wrap up the episode.

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Episode 56: Sensor Networks

Filed in Episodes by on May 17, 2007 1 Comment
Episode 56: Sensor Networks

In this episode we discuss sensor networks with our guest Steffen Schaefer, who is the Technical Thought Leader for Sensors & Actuator
Solutions at IBM. The discussion resolves around the TREC device, which can be mounted on containers to track them on their journey over seas, railway tracks and roads. The TREC is a small embedded device developed by Steffen’s employer, IBM, that has various sensors and communications channels.

In the episode we first talked about container transport in general, and then looked at how the TREC device works – specifically, it’s hardware, software and power management. We then looked at the necessary backend infrastructure. The main part of the discussion covered the communication between the device and the backend, using technologies such as Zigby, GSM and satellite communications. We also looked at the middleware infrastructures used, such as the MQtt messaging tool.

We closed the episode with a little discussion of the “Internet of Things” and some discussion about embedded software devleopment in general. Note that SE Radio will feature more embedded topics in the future – an introduction to embedded development will be put online soon.

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Episode 55: Refactoring Pt. 2

Filed in Episodes by on May 7, 2007 1 Comment
Episode 55: Refactoring Pt. 2

In the first episode on Refactoring we talked about the basic ideas behind refactoring and some base principles why refactoring is a key part of software engineering. Now we move on to more complicated refactorings and discuss three major situations, their problems and possible solutions: advanced refactorings in large projects that can hardly be finished in a few minutes or hours and refactoring in larger teams. Also covered are the refactoring of published APIs and how merciless refactoring could be aligned with backward compatibility of published APIs, and refactorings that affect more than just code like for example database schemas.

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