Design, implementation and evaluation of the Hedy programming language

Abstract

Hedy is a programming language that implements the gradual programming approach in which the goal is to lower the syntax barrier by starting with a very simple language, and gradually adding both concepts and refining syntax. This paper describes the design and implementation of Hedy, as well as a first user study involving 39 children between the ages of 11 and age 14 who followed online lessons for six weeks. Based on lesson observations and a written survey filled out by the participants, we aim to understand the impact of using a gradual language. Our findings show that children appreciate the gradual nature of Hedy, find Hedy easy to learn and especially appreciate the power to control the difficulty of Hedy themselves. They also like and frequently use built-in educational features like example code snippets. Challenges of a gradual approach are the fact that commands sometimes change or overlap, and remembering commands and specific syntax remain a challenge. According to the participants, improvements could be made by making Hedy less sensitive to syntax errors, by improving error messages and by localizing keywords to the native language of children. • Details the full implementation of Hedy; the first gradual language for programming education. • Introduces an EBNF extension used for merging partial grammars to enable gradual language implementation. • Describes the first user study on Hedy.