Growing Programming Languages for Beginning Students

A student learning how to program learns best when the programming language and programming environment cater to her specific needs. These needs are different from the requirements of a professional programmer. Consequently, the design of teaching languages poses challenges different from the design of "Professional" languages. Using a functional language by itself gives advantages over more popular, professional languages, but fully exploiting these advantages requires careful adaptation to the needs of the students-as-is, these languages do not support the students nearly as well as they could. This paper describes the authors' experience adopting the didactic approach of How to Design Programs, focusing on the design process for their own set of teaching languages.