Lecture Notes

Course introduction and administration. Overview of course topics. Programming language paradigms. Brief history of programming languages. Compilation vs. interpretation. Issues and factors in programming language design.

An introduction to F#. Basic types and operators. Basic expressions and type checking. Tuple types.

Readings:

• Syllabus
• Introduction and Overview class notes
• F# Wikibook: Basic Concepts
• Lecture code 0

Variable binding. Variable scope ands scoping rules. Function definitions. Pattern matching. Patterns in let expressions and in function definitions.

The match construct. Meaning and common uses. Scoping of pattern variables in match. Use of match in function definitions.
Algebraic datatypes (ADT), or discriminated unions, in F#. Basic uses. Pattern matching with ADTs. Functions accessing and manipulating ADTs.

Readings:

• Lecture code 1
• Lecture code 2
• Lecture code 3
• F# Wikibook: Basic Concepts
• F# Wikibook: Declaring Values and Functions
• F# Wikibook: Pattern Matching Basics
• F# Wikibook: Discriminated Unions

Using ADTs to encode arithmetic expressions. Simple evaluators of arithmetic expressions.

Parametric types in F#. Motivation and uses. Parametric algebraic datatypes. F# Lists. Basic features and examples. Using pattern matching and recursion to implement functions over lists.

Evaluating arithmetic expressions with variables.

Readings:

• Lecture code 4
• Lecture code 5
• F# Wikibook: Lists
• Chap 1 of Sestoft

Extending the basic expression language with variables and with let binders. Evaluating expressions with let binders. Examples.

Implementing finite sets in F# using lists. Free and bound variables, variable scope.

Compiling expressions with variable names to expressions with variable indices.

Readings:

• Lecture code 6
• Lecture code 7
• Sections 2.1–2.3 of Sestoft.
• Section 2.4 of Sestoft.

Stack machines for expression evaluation, with variables and without. Compiling expressions to stack machine code. Running stack machine code. Examples. Producing byte code.

Readings:

• Lecture code 8
• Chap. 2 of Sestoft.

Formal languages. Regular expressions. Languages generated by regular expressions. Finite Automata. Finite automata as recognizers of regular languages. Examples.

Non-deterministic finite-state automata (NFAs). Definition and examples. Relationships between NFAs, deterministic automata and regular expressions.

Applications to programming languages.

Readings:
Lecture notes by Wayne Goddard on

• Finite Automata
• Regular Expressions
• Nondeterministic Finite Automata

• Conversions Among FAs and REs
• Properties of Regular Languages

Context-free grammars and languages. Definition and examples. Systematically generating CFG's from regular expressions.

Derivations and derivation trees. Ambiguous grammars. Examples and exercises.

Pushdown automata. Recognizing context-free languages with pushdown automata. Examples.

Readings:
Lecture notes by Wayne Goddard on

• Context-Free Grammars
• Derivation Trees

• Push-down Automata (by Radu Grosu)
• The Chomsky Hierarchy (by Wayne Goddard)

Midterm 1

From concrete to abstract syntax. Lexers, parsers and generators. Specifying lexers and parsers in F# with fslex and fsyacc.

A concrete syntax and a lexer and parser for a simple language of expressions.

Example of pushdown automaton parser generated by fsyacc.

• Sect. 3.2-3.6 of Sestoft
• expr code (see README files in zip archive)
• FSLex and FSYacc documentation

• Sect. 3.8-3.9 of Sestoft

Micro-ML, a simple language of recursive functions: concrete and abstract syntax. Lexer and parser specification.

Examples of micro-ML programs. Interpreting micro-ML. Specifying interpreters formally with evaluation rules. Implementation of specification in F#, via eval function. Static and dynamic scope.

• Sect. 4.1-4.7 of Sestoft
• fun code (see README files in zip archive)

• F# : Modules and Namespaces

Static vs. dynamic typing. Adding type-checking to micro-ML. Formal type-checking rules. Implementation of type checker.

Readings:

• Sect. 4.8-4.11 of Sestoft
• Micro-ML class notes
• TypedFun code

Higher-order functions in F#. Currying and partial evaluation. Higher-order combinators. Examples.

Extending Micro-ML to higher-order functions. Comparison between interpreters for first-order and higher-order micro-ML. Examples of higher-order programming in Micro-ML.

Eager and Lazy evaluation. Call by value, call by name. Advantages and disadvantages.

• Sect. 5.1-5.5 of Sestoft
• Functions as First-Class Values
• Lecture code 9
• highfun code

Imperative programming. Main concepts. Programs as state transformers. A naive imperative language. Environment and store.

• Sect. 7.1-7.2 of Sestoft
• Lecture code 12 of a naive imperative language's AST and interpreter.
• Lecture notes on imperative programming and micro-C

• Lecture code 11 on immutable maps, expression sequences, and option types
• F# : Sets and Maps
• F# : Option Types

The C programming language. Integers, pointers and arrays in C. Type declarations in C. The micro-C language. Interpreting micro-C programs. Local and global environments. Memory model. Store and activation records. Interpreting statements, declarations, expressions, and variable access in the presence of side effects. Relationship between & (address) and * (pointer dereferencing) operators.

• Chap. 7 of Sestoft
• microc code
• Lecture notes on imperative programming and micro-C

• Online C tutorial

A virtual stack machine for micro-C. Instruction set, concrete and symbolic. Virtual machine as implemented in Java and C. The structure of the runtime stack. Compiling micro-C to machine code: overview of main approach.

• Sect. 8.1-8.8 of Sestoft
• microc code with virtual stack machines (in C and in Java) and usage examples.
• Lecture notes on micro-C compilation

Brief overview of basic concepts in object-oriented languages. Memory model for object-oriented languages. Stack and heap allocation.

Real-world virtual machines. An overview of the Java virtual machine.

• Sect. 9.1-9.3 of Sestoft
• virtual code with examples of the Java Virtual Machine usage
• Lecture notes on the Java virtual machine

Project Q&A sessions.