Hedy: Creating a gradual programming language

Felienne Hermans

Associate Professor

Leiden Institute of Advanced Computer Science

Hedy: Creating a gradual programming language

Hedy is a gradual programming language to make learning programming easier. The core idea of Hedy is that it uses different language levels. In level 1, there is hardly any syntax at all, for example printing is done with:

print hello DevRelCon!

In every level, new syntax and concepts are added, until kids are doing a subset of Python in level 20 with conditions, loops, variables and lists. The levelled approach means that learners do not have to learn all syntax rules at once. Hedy is aimed at children that want to get started with textual programming languages, but for whom starting with Python might still be too complex.

Hedy is open source, runs in the browser, is free to use, and available in 24 different languages (Including English, Spanish, Chinese and Hindi). Hedy was launched in early 2020 and since then almost 2 million Hedy programs have been created by children worldwide. Try Hedy at www.hedycode.com.

In this talk, Felienne will dive into the pedagogy behind Hedy, but also expand on the technical aspects of Hedy. For example, a set of increasingly complex grammars, rather than one grammar, poses new challenges for language design.

About Felienne

Felienne is associate professor at the Leiden Institute of Advanced Computer Science at Leiden University, where she heads the PERL research group, focused on programming education. She also works at the Vrije Universiteit Amsterdam one day a week, where she teaches prospective computer science teachers and she is a high-school CS teacher herself at Lyceum Kralingen.

Felienne is the creator of the Hedy programming language, and was one of the founders of the Joy of Coding conference. Since 2016, she has been a host at SE radio, one of the most popular software engineering podcasts on the web. Felienne is the author of “The Programmer’s Brain” a book that helps programmers understand how their brains work and how to use it more effectively. In 2021, Felienne was awarded the Dutch Prize for ICT research.

Felienne is a member the board of I&I, the Dutch association of high-school computer science teachers, and of TC39, the committee that designs JavaScript. Felienne blogs at felienne.com