The Racket language provides a variety of ready-to-use data structures and containers, however each such container has advantages and disadvantages when it comes to performance. The “everything is a list” approach makes things simple when you are learning Racket, but if you start using it for more complex programs, you need to be aware that lists are not always the best data structure to use. This guide looks at a few alternatives.
When experimenting with a new data visualization or data analysis method, it is simpler to write a prototype as a separate application, to evaluate if it is worthwhile investing the effort of adding a full feature to ActivityLog2, this post illustrates the process used to write a “training load” dashboard application in Racket.
The Racket GUI library provides a
text-field% control which allows input of arbitrary text, but only basic functionality by default. However, the class is designed to be extensible and in this article we’ll look at how to extend this control to provide a more modern input control with a cue text and input data validation.
pasteboard%object is an editor of
snip% objects and it implements some features that make sense for an editor: for example, you can select multiple snips and drag them around with the mouse, and you can move selected snips using the keyboard, you can also add any kind of snip, not just chess pieces to the pasteboard. Since none of these features are useful or desirable for a chess board game we will look at how to disable them.
This is a continuation of the previous blog post, where the racket
pasteboard% features are explored by implementing a Chess Game Board. In this blog post we look at how to restrict piece movements to chess board squares, permit only valid moves and implement turn based game play.
The Racket GUI library provides an “editor toolkit” which can be used to implement programs that use an interactive graphical canvas where objects can be moved around with the mouse. This toolkit has good reference documentation, however this documentation can be somewhat overwhelming, and it is not always clear how to begin writing such interactive application, or how to achieve some basic functionality, so I wrote a tutorial on how to implement a chess board game in Racket using the
snip% classes which are part of the GUI library.
A Racket implementation of a data frame structure, which allows efficient manipulation of data that is organized in rows and columns. It was originally written as part of the ActivityLog2 project, than moved into its own Racket package.
This is a Racket GUI Widget which can display maps based on Open Street Map tiles — it allows embedding maps in Racket GUI applications. I originally wrote this code as part of the ActivityLog2 project and, since I wanted to use it in other projects, I decided to move it onto a separate package and publish it to the Racket package server.
A Garmin fitness device can use workouts during a bike or run activity: they are a collection of steps with a duration and intensity (such as heart rate, pace or power). While running or biking, the device keeps track of the duration and will sound an alarm if the intensity is too high or too low. Workouts can be created on the Garmin Connect website, but I decided to write my own application for creating workouts.