HASKEU: An editor to support visual and textual programming in tandem

Typical text editors allow “Free Typing” (syntax/semantics-free editing) to construct and maintain textual programs rapidly and easily by expert programmers, but this style does not support novice programmers learning the syntax and semantics of a language. On the other hand, visual editors enforce correct construction of programs using syntax-directed editing. Additionally, they clearly represent the program flow in a visual way. Both textual and visual editors have pros and cons for learners and experts. This paper argues that an editor that offers both a visual and a textual representation of the program in tandem has advantages to offer both learner and expert programmers. It describes the editor, HASKEU, which embodies this principle by providing visual and textual support for editing Haskell functional programs.