programming languages lecture 1 : notes
Assessment
written Exam - lab based (70%) programming Assignment (25%) weekly quizzes (5%)
PL pipeline (high level)
parsing → type checking → desugaring → IR conversion → optimisation → interpretation/compilation
PL Design
Syntax
constructs of the language? how do expressions or statements look?
Typing rules
can we trim nonsensical answers going into the programming language?
semantics
what the programming language does when running it?
programming paradigms
the right tool for the job
imperative
Program Counter + Call Stack + state have a current place in the program and alter the position
expressions vs statments
Statment: an instruction / computation step (doesnt return anything)
Expression: a term when evaluated reduces to a value
Expressions can be contained within a statement
functional
everything is an expression first class functions (functions are treated as variables)
object-Oriented
consists of some state(fields), and some functions that operate on the state(methods) encapsulation : don’t expose internal state
Syntax
regex
for recognising tokens for regular languages - they can be recognised by finite state automaton
grammer
set of formal rules specifiying how ot constrcut a sentence: Terminal symbols : symbols that occur in a sentence non terminal symbols : sentence symbol : production rules :