Programming languages and tools

What programmers work with

• Language syntax
• Development environments
• Debugging & reading tools

Programming languages and tools

Programmers are users too!

What language syntax is easy to understand?

What programming abstractions fit mental models?

What tools can help making sense of code?

What real programmers actually struggle with?

Syntax: APL and Visual Basic .NET

Integrated Development Environments

Interacting with programming systems

Classic software engineering

• Implement one feature
• Compile your project
• Run and provide inputs

REPL - Read, Eval, Print Loop

Type line, run it, see result

Immediate feedback, but limited interaction

Jupyter Notebooks

REPL with chart output

Can edit previous notebook cells

What is the mental model of execution?

Excel

Why finance and insurance companies (over)use it
so much?

Other forms of interactions
Programming by example

Programming languages and tools

What can we study using user experience methods

Compare syntax using controlled studies

Heuristic evaluation (consistency, system status)

How are systems used in corporate environment?

GOMS models of data analysis tasks

Metaphors for understanding code abstractions

Code, languages and notations

Language syntax

• Symbols or words
• Structure of nesting
• How much it matters?

Programming as writing

• How we compose programs?
• Top-down vs. bottom-up
• Metaphors used in code

An empirical investigation into program-ming lang-uage syntax

Which of them is easier to use?

Controlled lab study, using 6 simple tasks

Code, languages and notations

An empirical look at programming language syntax

Statistically significant, scientific results

Used as a basis for Quorum language design

Random language is better than Perl!

Limited scope - syntax might be detail

Novices only - hard to evaluate with experts

Metaphors for variables

Variable is like a label

A variable is like a label that one can place on one value, like a temperature or the age of a person

Variable is like a box

A variable is like a box that can contain a value, like a piggy bank or a shoe box.

Comparing metaphors for variables in programming education

Variable as a label or as a box

Taught ~200 using label and ~200 using box

Student using box metaphor did better

Box leads to multiple values misconception

Metaphor used for learning programming

Teaching programming

Learning how to program is hard

• How to make it easier?
• What language to teach?
• Design a better one?

LOGO and Turtle graphics

Turtle moves around screen with a pen

Logo: Developmental psychology principles

Learning by doing

• Jean Piaget's constructivism
• Create knowledge by interacting

Stages of cognitive development

1. Sensorimotor stage
2. Preoperational stage
3. Concrete operational stage
4. Formal operational stage

Scratch

Learning by doing tradition

Supports multiple cognitive stages

Teaching programming

Using experiments to guide language design

"Programming" a Pacman

Write a statement that summarizes how computer should move Pacman

Twelve 10 year olds

Responses categorized
by 5 CS students

Programming style

54% - rules or event-based
When Pacman eats all dots, he goes to the next level

18% - global constraints Cannot go through a wall

16% - declarations/other
There are 4 monsters.

12% - imperative
Display this string.
Play this sound.

HANDS System: Logic written using event-based rules!

Code, navigation and search

Searching through code

• Most of time is spent understanding code
• Navigation through codebase

Searching through possibilities

• Search as a metaphor for problem solving
• Searching for the right program

Code search

Study what developers search for
and why

Searching through code

Code search study from Google

Using data from logs and surveys

Analyze techniques and motivations for search

Finding very (17%) or somewhat (44%) familiar code

Learning how code works (46%) or how to use it (21%)

Searching through state space

State space

• Possible game states
• User interface options
• Possible programs

Interaction questions

• Depth of the goal
• Breath-first or depth-first
• Allow lookahead when searching

Programming interaction as search
Searching for a program in program space

Programmers and other specialist users

Applying HCI methods in practice
Problems: Improving efficiency and understanding
Methods: Surveys, studies, metaphors, log analysis

Teaching programming to novices
What is the best metaphor for variables?
What is natural language of programming?

Human computer interaction as search
Searching for options in user interface
Searching the space of possible programs

CO582: Programmers and other specialist users

What you should remember from this lecture

• Kinds of question and methodology, not problems
• Usability, efficiency, ease of comprehending
• Expert analysis, experiments and their limitations

Tomas Petricek
t.petricek@kent.ac.uk | @tomaspetricek

Books

• Human Error, James Reason
• The Design of Everyday Things, Don Norman

Papers and links

• Experimental Study of Vertical Flight Path Mode Awareness, Eric N. Johnson, Amy R. Pritchett

code search https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43835.pdf

hands https://faculty.washington.edu/ajko/papers/Myers2016ProgrammersAreUsers.pdf https://www.cs.cmu.edu/~NatProg/papers/Myers2004NaturalProgramming.pdf

pacman http://alumni.cs.ucr.edu/~ratana/PaneRatanamahatanaMyers00.pdf

hci http://www.pgbovine.net/what-is-hci-research.htm

felienne http://www.felienne.com/archives/6063

learning scratch https://www.tandfonline.com/doi/full/10.1080/08993408.2013.832022?casa_token=MrxrpNkWjo0AAAAA%3APtWPbArMp4_mTUHfMNz1ewPopN7f7-rbeYTuZs7HF1empsl9I883sB8Dsmx_qrnqZ9bwAcckyW0L&

How do people naturally think about computation? Cyrus Omar https://www.cs.cmu.edu/~comar/NaturalComputation.pdf