Class Notes

These are the class note files, each has a rendered HTML version as well as a text file version (which can be more convenient for reading off-line and for quick search and reference). Note that the last two entries in this list are special: one has all of the notes we covered in one file, and one has the notes we have yet to reach.

Lecture #1 (text)     Tue, Jan 7	Intro to CS4400/CS5400
Lecture #2 (text)     Tue, Jan 7	Intro to Programming Languages Intro to Racket Side-note: “Goto Statement Considered Harmful” Quick Intro to Racket Lists & Recursion Some Style Tail calls Sidenote on Types Side-note: Names are important
Lecture #3 (text)     Tue, Jan 14	BNF, Grammars, the AE Language Simple Parsing The match Form The define-type Form The cases Form Semantics (= Evaluation) Side-note: Compositionality
Lecture #4 (text)     Tue, Jan 14	Implementing an Evaluator Implementing The AE Language Intro to Typed Racket Bindings & Substitution
Lecture #5 (text)     Tue, Jan 21	WAE: Adding Bindings to AE Evaluation of with
Lecture #6 (text)     Tue, Jan 21	Evaluation of with (contd.) Formal Specs Lazy vs Eager Evaluation de Bruijn Indexes
Lecture #7 (text)     Tue, Jan 28	Functions & Function Values Implementing First Class Functions Side-note: how important is it to have anonymous functions? The FLANG Language
Lecture #8 (text)     Tue, Jan 28	The FLANG Language (contd.) Introducing Racket’s lambda Using Functions as Objects Using define-type for new “type aliases” Currying Using Higher-Order & Anonymous Functions Side-note: “Point-Free” combinators This is not Runtime Code Generation
Lecture #9 (text)     Tue, Feb 4	Substitution Caches Implementation of Cache Functionality Formal Rules for Cached Substitutions Evaluating with Substitution Caches
Lecture #10 (text)     Tue, Feb 4	Dynamic and Lexical Scopes Dynamic versus Lexical Scope
Lecture #11 (text)     Tue, Feb 11	Implementing Lexical Scope: Closures and Environments Fixing an Overlooked Bug Lexical Scope using Racket Closures More Closures (on both levels) Types of Evaluators Feature Embedding
Lecture #12 (text)     Tue, Feb 11	Recursion, Recursion, Recursion Recursion without the Magic The Core of make-recursive Denotational Explanation of Recursion The Y Combinator The main property of Y Yet another explanation for Y Typing the Y Combinator [extra]
Lecture #13 (text)     Tue, Feb 18	Lambda Calculus — Schlac Church Numerals More Encodings Alternative Church Encoding Implementing define-type & cases in Schlac
Lecture #14 (text)     Tue, Feb 18	Recursive Environments Recursion: Racket’s letrec Implementing Recursion using letrec
Lecture #15 (text)     Tue, Feb 25	Implementing rec Using Cyclic Structures Boxes and Mutation
Lecture #16 (text)     Tue, Feb 25	Types for Boxes Boxof’s Lack of Subtyping Implementing a Circular Environment
Lecture #17 (text)     Tue, Feb 25	Variable Mutation State and Environments Implementing Objects with State The Toy Language
Lecture #18 (text)     Tue, Mar 11	Compilation
Lecture #19 (text)     Tue, Mar 11	Is this really a compiler?
Lecture #20 (text)     Tue, Mar 18	Lazy Evaluation: Using a Lazy Racket Lazy Evaluation: Some Issues Lazy Evaluation: Shell Examples Lazy Evaluation: Programming Examples
Lecture #21 (text)     Tue, Mar 18	Side Note: Similarity to Generators and Channels Call by Need vs Call by Name Example of Feature Embedding Implementing Laziness (in plain Racket) Sloth: A Lazy Evaluator
Lecture #22 (text)     Tue, Mar 25	Getting more from Sloth The Sloth Implementation Shouldn’t there be more ExprV promises? Implementing Call by Need
Lecture #23 (text)     Tue, Mar 25	Side Effects in a Lazy Language Designing Domain Specific Languages (DSLs)
Lecture #24 (text)     Tue, Apr 1	Syntax Transformations: Macros Macro Problems Complexity of S-expression transformations Scoping problems Scheme (and Racket) Macros Meta Macros
Lecture #25 (text)     Tue, Apr 1	Lazy Constructions in an Eager Language Recursive Macros Another example: a simple loop Yet Another: List Comprehension Problems of syntax-rules Macros Racket’s “Low-Level” Macros
Lecture #26 (text)     Tue, Apr 1	Solving the syntax-rules problems [extra] Breaking Hygiene, How Bad is it? [extra] Macros in Racket’s Module System [extra] Defining Languages in Racket [extra] Macro Conclusions Side-note: macros in mainstream languages
Lecture #27 (text)     Tue, Apr 8	Types What is a Type? Our Types — The Picky Language Typing control Extending Picky Implementing Picky Improving Picky
Lecture #28 (text)     Tue, Apr 8	Improving Picky (contd.) Typing Recursion Extending Picky with recursion Typing Data Judgments for recursive types
Lecture #29 (text)     Tue, Apr 8	“Runaway” instances [extra] Type soundness Explicit polymorphism [extra] Polymorphism in the type description language [extra] Type judgments for explicit polymorphism and execution [extra] Explicit polymorphism conclusions [extra]
Lecture #30 (text)     Tue, Apr 15	Web Programming Basic web programming Continuations: Web Programming Simulating web reading More Web Transformations Transforming a recursive function Using sum/k Converting stateful code Converting higher order functions
Lecture #31 (text)     Tue, Apr 15	Highlevel Overview on Continuations An Automatic Continuation Converter Continuations as a Language Feature Continuations in Racket
Lecture #32 (text)     Tue, Apr 15	Playing with Continuations [extra] The Ambiguous Operator: amb [extra] Generators (and Producers) [extra] Delimited Continuations [extra] Continuation Conclusions Sidenote: JavaScript: Continuations, Promises, and Async/Await
All notes (text)     Tue, Apr 15	All class notes in a single file, convenient for searching through all of the material that we covered.

Handouts

• Email and Piazza Policies: Guidelines for writing posts
• Style Guide: Guidelines for writing better code
• Tips: Useful tips for PL work
• FAQ: Common frequently asked questions
• #lang pl work vs Fundies: Work with #lang pl vs Fundies
• About PLQ: What are these PLQs?
• Debugging Macros: For the macro homework

Interpreters

• ae.rkt — The AE interpreter (Lecture #4)
• wae.rkt — The WAE interpreter (Lecture #5)
• flang.rkt — The Flang interpreter (Lecture #8)
• flang-env.rkt — The Flang interpreter, using environments (Lecture #11)
• church.rkt — Making Schlac into a practical language (not an interpreter) (Lecture #13)
• church-alternative.rkt — An alternative “Church” encoding: use lists to encode numbers (Lecture #13)
• flang-box.rkt — The FLANG-BOX interpreter (Lecture #16)
• toy.rkt — The TOY interpreter (Lecture #17)
• sloth.rkt — The SLOTH interpreter (Lecture #22)
• sloth-cached.rkt — A call-by-need version of the SLOTH interpreter (Lecture #22)
• mylang.rkt — A language that is built as an extension on top of Racket (Lecture #26)
• picky1.rkt — The Picky interpreter, verbose version (Lecture #27)
• picky2.rkt — The Picky interpreter, almost no explicit types (Lecture #27)
• picky3.rkt — The Picky interpreter, no explicit types (Lecture #28)
• web-base-library.rkt — Fake web interaction library (to be used with manual code CPS-ing examples) (Lecture #30)
• web-simple-language.rkt — Simulation of web interactions with a CPS converter (not an interpreter) (Lecture #31)
• cps-language.rkt — A language that is CPS-transformed (not an interpreter) (Lecture #31)
• continuation-based-web-library.rkt — Simulation of web interactions with Racket’s built-in continuation facility (Lecture #31)
• amb.rkt — The ambiguous operator and related utilities (Lecture #32)
• producer.rkt — An implementation of producer functions (Lecture #32)