isbn9789526046266

Python in the browser: Jype and the Online Python Tutor
Jype is a web-based integrated development environment for Python programming (Helminen, 2009). In
addition to serving as an IDE, Jype can be used for exploring teacher-given example programs and as a
platform for the automatic assessment of given programming assignments. Jype is intended specifically
for CS1 use and has a number of beginner-friendly features. Among these is support for program and
algorithm visualization.
Jype uses the Matrix framework (Korhonen et al., 2004) for visualizing data structures such as arrays
and trees automatically when they appear in programs. Jype also visualizes the call stack in a richer way
than a typical visual debugger, as illustrated in Figure 11.26.
Another new, web-based system for visualizing small Python programs is Online Python Tutor (Guo,
n.d.), shown in Figure 11.27. Like Jype, it allows the user to step forward and backwards in a Python
program at the statement level, and supports the distribution of teacher-given examples and small
programming assignments with automatic feedback.
Functional programming: WinHIPE and others
WinHIPE is an education-oriented IDE for functional programming that includes a program visualization
functionality (Pareja-Flores et al., 2007). WinHIPE visualizes an execution model of pure functional
programs that is based on rewriting terms (no assignment). The user configures each animation by
selecting which aspects are to be visualized and in what order term-rewriting proceeds in the visualization.
Using this facility, teachers can produce and customize dynamic visualizations of selected examples, which
can be exported for students to view. When a visualization is being viewed, the evaluation of expressions
is shown step by step, and the user can step back and forth in the evaluation sequence.
Unlike many of the other visualization tools in this review, WinHIPE is designed to scale up to handle
larger programs. WinHIPE is not specifically directed at CS1 – the authors have used it in more advanced
courses (Pareja-Flores et al., 2007; Urquiza-Fuentes and Velázquez-Iturbide, 2007) – but is a plausible
choice for beginners as well.
An earlier system for visualizing the dynamics of functional programs (in the Miranda language) was
presented by Auguston and Reinfelds (1994). Mann et al. (1994) reported a study using LISP Evaluation
Modeler, which traced the evaluation of LISP expressions. They found positive transfer effects from the
use of the system for debugging, and their students were eager to use it. ELM-ART (see, e.g., Weber and
Brusilovsky, 2001) is an intelligent LISP programming tutor for beginners, which features a component
that visualizes expression evaluation. The DrScheme/DrRacket IDE for the Scheme language also uses
some visual elements to present program dynamics, among its other beginner-friendly features (Findler
et al., 2002).
Visualizing before writing: CSmart
CSmart (Gajraj et al., 2011) takes an approach to visualization that is quite different from all the other
tools reviewed here. Instead of visualizing the execution of an existing program, the focus in CSmart is
on already visualizing each statement of a C program to the student before the student types it in.
CSmart is an IDE with a particular pedagogical goal: to assist the student in duplicating teacherdefined
example programs, thereby practicing programming fundamentals. The system knows exactly
what program it requires the student to write in each assignment. It instructs the student at each step
using text, graphics, and audio. Some of the guidance is teacher-annotated into the model solutions,
some generated automatically. Various visual metaphors have been built into the system to illustrate the
runtime semantics of the programming language. An example is shown in Figure 11.28.
Gajraj et al. (2011) report that their students liked it.
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