1 Making Programming Easier by Making it More Natural Brad A. Myers Human-Computer Interaction...

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Making Programming Easier by Making it More NaturalMaking Programming Easier by Making it More Natural

Brad A. MyersBrad A. MyersHuman-Computer Interaction InstituteHuman-Computer Interaction InstituteSchool of Computer ScienceSchool of Computer ScienceCarnegie Mellon UniversityCarnegie Mellon University

http://www.cs.cmu.edu/~bamhttp://www.cs.cmu.edu/[email protected]@cs.cmu.edu

Brad MyersBrad MyersCMU - HCI InstituteCMU - HCI Institute 2

The User Interface of Programming Languages

Programming is a human activity Want to improve the ability of people to program It makes sense to look at the human side

Programming is a human activity Want to improve the ability of people to program It makes sense to look at the human side


Who are the Authors?

• Not just professional programmers– Many languages aimed at

“part-time” or novice programmers

• Not just professional programmers– Many languages aimed at

“part-time” or novice programmers

• End User Programming!• End User Programming!


Why EUP?

By 2005, 55 million end-user programmers Compared to only 2.75 million professional programmers Use spreadsheets, CAD systems, special-purpose

scripting and visual languages, etc.

These languages are unnecessarily hard to use and prone to errors Errors in spreadsheets and other end-user-created

software costs companies millions of dollars

By 2005, 55 million end-user programmers Compared to only 2.75 million professional programmers Use spreadsheets, CAD systems, special-purpose

scripting and visual languages, etc.

These languages are unnecessarily hard to use and prone to errors Errors in spreadsheets and other end-user-created

software costs companies millions of dollars


Design of New Languages

How make design decisions? Designer’s intuition Similarity to other languages

But many have known problems

Key concept: If you care about usability and learnability:

Can leverage off of what is known andwhat can be learned about people

to guide design decisions

How make design decisions? Designer’s intuition Similarity to other languages

But many have known problems

Key concept: If you care about usability and learnability:

Can leverage off of what is known andwhat can be learned about people

to guide design decisions


— Allen Newell and Stuart Card, 1985— Allen Newell and Stuart Card, 1985

“Millions for compilers but hardly a penny for understanding human programming language use. Now, programming languages are obviously symmetrical, the computer on one side, the programmer on the other. In an appropriate science of computer languages, one would expect that half the effort would be on the computer side, understanding how to translate the languages into executable form, and half on the human side, understanding how to design languages that are easy or productive to use.... The human and computer parts of programming languages have developed in radical asymmetry.”

“Millions for compilers but hardly a penny for understanding human programming language use. Now, programming languages are obviously symmetrical, the computer on one side, the programmer on the other. In an appropriate science of computer languages, one would expect that half the effort would be on the computer side, understanding how to translate the languages into executable form, and half on the human side, understanding how to design languages that are easy or productive to use.... The human and computer parts of programming languages have developed in radical asymmetry.”


( )not (paint.color == red or paint.color == orange) Research shows that these differences between

natural languages and computer languages hurt understanding

( )not (paint.color == red or paint.color == orange) Research shows that these differences between

natural languages and computer languages hurt understanding

Examples of Problems

if is_man(x) and is_woman(x) then raise_hand(x); This issue with “and” applies to other natural

languages as well.

if is_man(x) and is_woman(x) then raise_hand(x); This issue with “and” applies to other natural

languages as well.

The men and women here raise your hands!The men and women here raise your hands!

Find a paint that is not red or orangeFind a paint that is not red or orange not paint.color == red or paint.color == orange not paint.color == red or paint.color == orange


Why Study This? There are many known problems

Programming is still hard to learn and hard to do

Little knowledge to guide designs The language which is currently popular seems to

have about a 7 to 12 year window Fortran, PL/1, Pascal, C, C++, Java, (maybe C# ?) … So new languages are always being created

We may influence design by identifying problems Java / C# took some into account

We certainly won't if we don't try, or if we don't know what to say!

There are many known problems Programming is still hard to learn and hard to do

Little knowledge to guide designs The language which is currently popular seems to

have about a 7 to 12 year window Fortran, PL/1, Pascal, C, C++, Java, (maybe C# ?) … So new languages are always being created

We may influence design by identifying problems Java / C# took some into account

We certainly won't if we don't try, or if we don't know what to say!

Gentle Slope Systems

Difficultyof

Use

Goal

Programming in C++

MFC

Program Complexity and Sophistication

C Programming

LabView

Stagecast

Creator

Visual Basic

Basic

C Programming

What we are doing...

Studying the People


Natural Programming Research

Try to provide a more scientific basis for programming language design

Apply results of Empirical Studies of Programmers and Human-Computer Interaction to programming language design

New studies to fill in gaps

Design new programming languages and environments based on these results

Try to provide a more scientific basis for programming language design

Apply results of Empirical Studies of Programmers and Human-Computer Interaction to programming language design

New studies to fill in gaps

Design new programming languages and environments based on these results


Why Would Being Natural be Good?

Language should be close to user’s plan “Programming is the process of transforming a mental

plan into one that is compatible with the computer.” — Jean-Michel Hoc

Language should be close to user’s plan “Programming is the process of transforming a mental

plan into one that is compatible with the computer.” — Jean-Michel Hoc

Example: Inserting item into 3rd place of high score list

Easy by Direct Manipulation (in a spreadsheet) Difficult to program:

Loop, starting at end of array, shuffle items down, then insert

Example: Inserting item into 3rd place of high score list

Easy by Direct Manipulation (in a spreadsheet) Difficult to program:

Loop, starting at end of array, shuffle items down, then insert


Why Would Being Natural be Good? #2

Directness (as in “Direct Manipulation”) “Distance between one's goals and the actions required

by the system to achieve those goals.”— Hutchins, Hollan and Norman

Directness (as in “Direct Manipulation”) “Distance between one's goals and the actions required

by the system to achieve those goals.”— Hutchins, Hollan and Norman

Example: Example:

vs.

Let Shape1.FillColor = &H00FF00FF&

vs.

Let Shape1.FillColor = &H00FF00FF&


Background Research

Empirical Studies of Programmers and HCI results not being used in the design of new languages 30 years of research on what makes languages hard to

learn and error-prone Java / C# looping, etc.

Summarized in our comprehensive tech report— John Pane and Brad Myers, “Usability Issues in the Design of

Novice Programming Systems” TR# CMU-CS-96-132. Aug, 1996.http://www.cs.cmu.edu/~pane/cmu-cs-96-132.html

Empirical Studies of Programmers and HCI results not being used in the design of new languages 30 years of research on what makes languages hard to

learn and error-prone Java / C# looping, etc.

Summarized in our comprehensive tech report— John Pane and Brad Myers, “Usability Issues in the Design of

Novice Programming Systems” TR# CMU-CS-96-132. Aug, 1996.http://www.cs.cmu.edu/~pane/cmu-cs-96-132.html


Our Research

Lots of gaps in prior research on people and programming

Develop knowledge that can be used in design Ph.D. thesis of John Pane

Available at:

http://www-2.cs.cmu.edu/~pane/thesis/

Lots of gaps in prior research on people and programming

Develop knowledge that can be used in design Ph.D. thesis of John Pane

Available at:

http://www-2.cs.cmu.edu/~pane/thesis/


Natural Programming Studies

How people naturally express programming concepts and algorithms1) Nine scenes from PacMan

2) Transforming and calculating data in a spreadsheet

Specific issues of language design3) Selecting specific objects from a group (“and”, “or”, “not”)

How people naturally express programming concepts and algorithms1) Nine scenes from PacMan

2) Transforming and calculating data in a spreadsheet

Specific issues of language design3) Selecting specific objects from a group (“and”, “or”, “not”)


Experimental Design

Question should not bias the answer So use pictures instead of textual descriptions Concentrate on kids, non-programmers

Subjects should not be “tainted” by programming knowledge

But test that the results generalize to adults and programmers

Question should not bias the answer So use pictures instead of textual descriptions Concentrate on kids, non-programmers

Subjects should not be “tainted” by programming knowledge

But test that the results generalize to adults and programmers

Usually Pacman moves like this.

Now let's say we add a wall.

Pacman moves like this.

Not like this.

Usually Pacman moves like this.

Now let's say we add a wall.

Pacman moves like this.

Not like this.

Do this: Write a statement that summarizes how I (as the computer) should move Pacman in relation to the presence or absence of other things.

Study 1


Second Study

Whether similar results from other domains and with adults

Developed 11 questions with scenarios using spreadsheets To test database access and operations More conventionally “computational”

Whether similar results from other domains and with adults

Developed 11 questions with scenarios using spreadsheets To test database access and operations More conventionally “computational”


Example Question, 2nd Study

No.

Firstname

Lastname

Group

1 Sandra Bullock 2 Bill Clinton 3 Cindy Crawford 4 Tom Cruise 5 Bill Gates 6 Whitney Houston 7 Michael Jordan 8 Jay Leno 9 David Letterman 10 Will Smith

Question 4• Describe in detailed steps what the computer should do to

categorize these people into 2 groups of ‘Gold’ and ‘Black’.

No.

Group

1 Sandra Bullock Gold 2 Bill Clinton Gold 3 Cindy Crawford Gold 4 Tom Cruise Gold 5 Bill Gates Black 6 Whitney Houston Gold 7 Michael Jordan Gold 8 Jay Leno Black 9 David Letterman Black 10 Will Smith Gold

Firstname

Lastname


Results

Rule-based style“If PacMan loses all his lives, its game over.”

Some use of Constraint style: “Pacman cannot go through a wall.”

Rule-based style“If PacMan loses all his lives, its game over.”

Some use of Constraint style: “Pacman cannot go through a wall.”

Set operations instead of iterations“Subtract 20,000 from all elements in Round 2”

— These tend to eliminate control structures

Set operations instead of iterations“Subtract 20,000 from all elements in Round 2”

— These tend to eliminate control structures


More Results

Most arithmetic used natural language style“When PacMan eats a big dot, the score goes up 100.”

Most arithmetic used natural language style“When PacMan eats a big dot, the score goes up 100.”

Operations suggest data as lists, not arrays People don’t make space before inserting

Objects normally moving“If PacMan hits a wall, he stops.”

so objects remember their own state

2/3 of the first study subjects drew pictures Usually to define the initial state

Operations suggest data as lists, not arrays People don’t make space before inserting

Objects normally moving“If PacMan hits a wall, he stops.”

so objects remember their own state

2/3 of the first study subjects drew pictures Usually to define the initial state


Implications for New Languages Use event-based style for dynamic events Provide operations on groups of objects Work to minimize the need for control structures

and variables Data structures that combine the capabilities of

lists + arrays + sets Support simple arithmetic in natural language

style (“add 1 to score”) Using mathematical notation such as > <

rather than words achieves better accuracy

Use event-based style for dynamic events Provide operations on groups of objects Work to minimize the need for control structures

and variables Data structures that combine the capabilities of

lists + arrays + sets Support simple arithmetic in natural language

style (“add 1 to score”) Using mathematical notation such as > <

rather than words achieves better accuracy


New Language and System: HANDS

Video


Conclusions

Can evaluate languages as to extent theyare “natural” Based on consistency, learnability, etc.

Can use this technique to answer questions for language designs Instead of just using the designer’s intuition Hopefully our data can help

Languages can be evaluated just like any other user interface using HCI principles and techniques

If you want a useable and learnable programming language, there are data and techniques that can help

Can evaluate languages as to extent theyare “natural” Based on consistency, learnability, etc.

Can use this technique to answer questions for language designs Instead of just using the designer’s intuition Hopefully our data can help

Languages can be evaluated just like any other user interface using HCI principles and techniques

If you want a useable and learnable programming language, there are data and techniques that can help


Credits

Support for this research has come in part from the National Science Foundation under

Grant No. IRI-9900452

andGrant No. IIS-9817527

For more information, see:

http://www.cs.cmu.edu/~NatProg

Support for this research has come in part from the National Science Foundation under

Grant No. IRI-9900452

andGrant No. IIS-9817527

For more information, see:

http://www.cs.cmu.edu/~NatProg

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Making Programming Easier by Making it More NaturalMaking Programming Easier by Making it More Natural

Brad A. MyersBrad A. MyersHuman-Computer Interaction InstituteHuman-Computer Interaction InstituteSchool of Computer ScienceSchool of Computer ScienceCarnegie Mellon UniversityCarnegie Mellon University

http://www.cs.cmu.edu/~bamhttp://www.cs.cmu.edu/[email protected]@cs.cmu.edu

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