Programming Languages (CS 152) – Spring 2022

Module Topic: Designing Usable Programming Languages
Module Author: Eliza Wells

Course Level: Upper Level Undergraduate
AY: 2020-2021

Course Description: “This course is an introduction to the theory, design, and implementation of programming languages. Topics covered in this course include: formal semantics of programming languages (operational, axiomatic, denotational, and translational), type systems, higher-order functions and lambda calculus, laziness, continuations, dynamic types, monads, objects, modules, concurrency, and communication.” (Course description) 

Semesters Taught: Spring 2018, Spring 2019, Spring 2021, Spring 2022, Spring 2023

Tags

• programming languages [CS]
• justice [phil]
• egalitarianism [phil]

Module Overview

This module focuses on how easy programming languages are to learn and use. In particular, students are introduced to the idea that programming language usability can be a problem of justice. The module introduces an egalitarian framework to help students see that morally irrelevant factors (e.g. vision impairment or not being a native English speaker) impact whether or not some populations are able to access the goods provided by computer science. The module discusses different elements of programming languages, such as documentation and intuitive design, that can impact programming language usability and asks students to think through ways that they can design programming languages so that morally irrelevant factors don’t impact usability.

    Connection to Course Material

Students in this course learn about the formal foundations of programming languages. They are taught about some values that good programming languages realize, such as memory-safety, and ways that they can both test and design for those values. This module considers another value that a good programming language should realize: usability. It encourages students to think about the people who use programming languages, and which people are able to sufficiently take advantage of the technically important features students learn about in the course.

Goals

Module Goals

1. Familiarize students with the philosophical concept of egalitarianism as a way of thinking about justice.
2. Explore how programming language usability is a justice issue.
3. Practice thinking through different ways in which students can design programming languages for usability.

    Key Philosophical Questions

1. Is programming language usability a justice issue?
2. What goods do individuals have access to through computer science?
3. What morally irrelevant traits impact individuals’ access to those goods?
4. What responsibility do computer scientists have to make programming languages usable?

Materials

    Key Philosophical Concepts

• Justice
• Egalitarianism
• Morally irrelevant traits

    Assigned Readings

• Selections from Ryan Long’s article on Egalitarianism from the Internet Encyclopedia of Philosophy

Implementation

Class Agenda

1. Overview.
2. Class discussion of the various goods to which being a computer scientist provides access.
3. Egalitarianism as a way of thinking about how those goods should be distributed.
4. Programming language usability as one case where the goods of computer science are distributed unequally.
5. Different ways in which programming languages can be more or less usable.
6. Thinking through usability using case studies of blind and low-vision programmers and non-native English speakers.

    Sample Class Activity

In small groups, students are asked to discuss:

1. What goods are at stake?
2. What factors limit access to those goods?
3. Are those factors morally relevant?

They are then presented with a case study of non-native English speakers who have difficulty using programming languages and asked:

1. What can we do about it?

    Module Assignment

Students are asked to respond to the following question on a class thread: Choose a programming language with which you are familiar. Which features of this language make it usable? For whom? Is there a way in which it could be made more usable (e.g. better documentation, more intuitive design, etc.)?

Lessons Learned

• Students were engaged with the content of the module and very willing to discuss how big-picture social factors (e.g. access to education, socioeconomic status, values in the community in which one is raised) impacted usability. In the course of the discussion, it became clear that designing programming languages to be more usable is a very small change in a complex system of injustice. Future versions of this module could do more to situate programming language usability within that bigger system.
• Future versions of this module could do more to highlight the different justice issues brought out by a) not being able to use any programming language versus b) not being able to use a particular programming language.
• One of the difficult questions of egalitarianism is “What counts as a morally irrelevant trait?” Students were able to bring out interesting edge cases, like motivation to learn a programming language, that may or may not be justice issues. Future modules could lean into this complexity.
• This module did not have time to discuss the question of how computer scientists can concretely realize their responsibility to make programming languages usable, and what burdens they ought to take on in order to achieve that. Students were interested in this question.