CPSC 311 September 13 2010
(define-type OpMapping
[opMapping (op symbol?) (impl procedure?)])
(opMapping '+ +)
Racket is cool. Why? Functions can be passed as values, second thing is that Racket Data looks like Racket programs, or vice versa
Concrete Syntax: (+ 5 7) == 5 + 7 == (5 7 +)
Abstract Syntax, a single way to represent the different forms of concrete syntax, generally forms trees
Statement, executes next statement after executing itself
Expression, returns a value (in Racket, expressions are functions)
Normally: Lexer (text) -> (tokens) Parser (abstract syntax tree) -> Interpreter (value)
Useful for checking for errors on tests:
(define (failed-tests)
(reverse (filter (lambda (x) (not (symbol=? (first x) 'good))) plai-all-test-results)))
Alt-p previous, alt-n next
Case, checks a symbol, cond checks a condition
