Creating Hedy: A gradual programming language 

Felienne Hermans | Universitair hoofddocent; Leiden Institute of Advanced Computer Science (LIACS)

Hedy is a gradual programming language to make learning programming easier, using different language levels. In level 1, there is hardly any syntax at all, for example, printing is done with: print hello!  New syntax and concepts are added in every level until kids are doing a subset of Python in level 18 with conditions, loops, variables and lists. The leveled approach means that learners do not have to learn all syntax rules at once. Hedy is aimed at children who want to start 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 is available in 29 different languages (Including English, Spanish, Chinese, Arabic and Hindi). Hedy was launched in early 2020 and since then more than 2 million Hedy programs have been created by children worldwide. Try Hedy at

In this talk, Felienne Hermans will dive into the pedagogy behind Hedy, but also discuss the technical aspects of Hedy. For example, a set of increasingly complex grammars, rather than one grammar, poses new challenges for language design, as do localized keywords, especially in non-Latin languages.