VLSS Special Issue on Blocks Programming

This special issue of the Journal of Visual Languages and Sentient Systems (VLSS) focuses on Blocks Programming. Over the past twenty years, blocks programming languages have evolved from research lab prototypes to practical tools used by tens of millions of people. The core idea behind these languages is simple: rather than constructing programs out of sequence of characters that are lexed into tokens that are parsed into syntax trees, why not construct syntax trees more directly by composing drag-and-drop visual fragments that represent the nodes of the trees? There are now a host of blocks languages that can be used for a wide variety of purposes, such as creating games, scripting 3D animations, inventing mobile apps, developing agentbased simulations, controlling robots, generating 3D models. and collecting/analyzing/visualizing scientific data. Educators have seized upon blocks languages as a way to introduce beginners to computer science concepts. Environments like Scratch, Blockly, Pencil Code, App Inventor, Snap!, AgentSheets/AgentCubes, and Alice/Looking Glass have become popular ways to introduce students (from grade schoolers through graduate students) to computational thinking and programming. This is done not only in traditional classrooms, but also in extracurricular settings via online activities like Code.org’s Hour of Code. But blocks environments are also a boon to a broader population whose primary goal is to “make stuff” rather than learn computer science principles. This includes artists, scientists, hobbyists, entrepreneurs, and other end users and socalled casual programmers who want to build computational artifacts for themselves, their families, their workplaces, their communities, and the world at large. There are many questions surrounding blocks languages. Why are they so popular? What are their key advantages and limitations compared to other programming environments? Do they really lower barriers to programming, or is that just hype? In what ways do they help and hinder those who use them as a stepping stone to traditional text-based languages? What are effective pedagogical strategies to use with blocks languages, both in traditional classroom settings and in informal and open-ended learning environments? How does the twodimensional nature of blocks programming workspaces affect the way people create, modify, navigate, and search through their code? Do blocks environments have any features that are worth incorporating into IDEs for traditional programming environments? What are effective mechanisms for multiple people to collaborate on a single blocks program when they are co-located or are working together remotely? Can blocksbased environments be made accessible to users with visual or motor impairments? These questions are being investigated by educators, software developers, and researchers from areas that include visual languages, human-computer interaction, programming languages, education, psychology, learning science, and data analytics. This special issue gives a sample of the kinds of research and development that is taking place in the blocks programming community.