A Programming Language

Two Variables

• x, y

Three Operations

• x++
• x--
• x = 0 ? L1 : L2

Example Program

(What does it do?)

L1: x++
    y--
    y = 0 ? L2 : L1
L2: ...

The above language is “equivalent to” every PL!

But good luck writing

• … QuickSort

• … Fortnite

• … Spotify!

So Why Study Programming Languages?

A different language is a different vision of life.

So Why Study Programming Languages?

The principle of linguistic relativity holds that the structure of a language affects its speakers world view or cognition.

Or more simply:

Programming Language shapes Programming Thought.

Language affects how ideas and computation are expressed

Course Goals

New languages come (and go …)

There was no

• Java 30 years ago
• C# 25 years ago
• Rust 15 years ago
• WebAssembly 5 years ago

What is CSE 130 about?

• Concepts in programming languages
• Programming paradigms
• Language design and implementation

Goal: Learn the Anatomy of PL

• What makes a programming language?
• Which features are fundamental and which are syntactic sugar?

Goal: Learn New Languages / Constructs

New ways to describe and organize computation, to create programs that are:

• Correct
• Readable
• Extendable
• Reusable

Goal: How to Design new Languages

New languages being designed in industry as we speak:

• Flow, React @ Facebook
• Rust @ Mozilla
• TypeScript @ Microsoft
• Swift @ Apple
• WebAssembly @ Google + Mozilla + Microsoft

Buried in every large system is a (domain-specific) language

• DB: SQL
• Word, Excel: Formulas, Macros, VBScript
• Emacs: LISP
• Latex, shell scripts, makefiles, …

If you work on a large system, you will design a new PL!

Goal: Enable You To Choose Right PL

But isn’t that decided by

• Libraries
• Standards
• Hiring
• Your Boss?!

Yes.

My goal: Educate tomorrow’s leaders so you’ll make informed choices.

What is CSE 130 not about?

Learning…

• JavaScript in January
• Haskell in February
• C++ in March

etc.

The Crew

Profs

Ranjit Jhala

• Professor at CSE since 2005

• Research: Tools and Techniques to make programs better

Many thanks to for taking over in weeks 1-2!

**Prof. Nadia Polikarpova

The Crew

Teaching Assistants

• Matt Kolosick
• Cole Kurashige
• George Sakkas

Tutors

• Rana Lulla
• Matthew Peng
• Melody Ruth

Course Syllabus

Functional Programming

• Lambda calculus (2 weeks)
• Haskell (6 weeks)

Logic Programming

• Prolog (2 weeks, maybe, but doubtful!)

QuickSort in C

void sort(int arr[], int beg, int end){
  if (end > beg + 1){
    int piv = arr[beg];
    int l = beg + 1;
    int r = end;
    while (l != r-1)
       if(arr[l] <= piv) l++;
       else swap(&arr[l], &arr[r--]);
    if(arr[l]<=piv && arr[r]<=piv)
       l=r+1;
    else if(arr[l]<=piv && arr[r]>piv)
       {l++; r--;}
    else if (arr[l]>piv && arr[r]<=piv)
       swap(&arr[l++], &arr[r--]);
    else r=l-1;
    swap(&arr[r--], &arr[beg]);
    sort(arr, beg, r);
    sort(arr, l, end);
  }
}

QuickSort in Haskell

sort []     = []
sort (x:xs) = sort ls ++ [x] ++ sort rs
  where
    ls      = [ l | l <- xs, l <= x ]
    rs      = [ r | r <- xs, x <  r ]

(Note: not a wholly fair comparison…)

Course Logistics

webpage

• Calendar
• Lecture notes
• Programming assignments

piazza

• Go-to place if you have a question or need help

Grading

• 5% Class participation (clicker questions)
• 25% Programming Assignments
• 35% Two Midterm Tu 1/30 and Thu 2/22
• 35% Final Tu 3/19
• 05% Piazza Extra Credit
  • To top 20 best participants

Assignments

6 programming assignments

• Released online
• At least a week before due date
• Via github classroom

Six late days

• used as whole unit
• 5 mins late = 1 late day
• at most 4 per assignment

No Groups

• Assignments must be submitted individually via github
• Ok to discuss with classmates, but solution must be your own

Exams

• Must be done at allotted time and location

• 2-sided ``cheat sheet’’

• The final is cumulative

Clickers

Make class interactive

• Help you and me understand what’s tricky

Not Optional

• Cheap ones are fine
• Respond to 75% questions

Clicker Protocol

1. Solo Vote
   • Think for yourself, select answer
2. Discuss
   • Analyze problem in groups
   • Reach consensus
   • Have questions, raise your hand!
3. Group Vote
   • Everyone in group votes
   • Hopefully the same way but not enforced
   • You don’t have to answer correctly to get points!
4. Class Discuss
   • What was easy or tricky?