kmicinski

#lang racket

;; CIS352 -- The Algebra of Programming
;; Spring 2026 -- Kristopher Micinski

;; Introduction:
;; 
;; Students often ask (in CIS352): "why learn Racket, a language with
;; an arcane syntax that I might not use outside of this class?" It is
;; a very reasonable question, and today we will answer it directly:

kmicinski

#lang racket
;; CIS352 -- Feb 3, 2026

;; Pattern matching:
;; □ -- Trees, manually
;; □ -- Recursion over trees
;; □ -- Introducing pattern matching
;; □ -- Matching list patterns ("quasipatterns")
;; □ -- Matching predicate patterns
;; □ -- Trees, and algebraic data types generally

kmicinski

#lang racket

;; CIS 352 -- Spring 2026
;; 1/27/26 (I believe)

;; quickanswer.harp-lab.com

;; the define form lets us define funcitons
;; (define (f x y z) e-body)
(define (both-even? n0 n1)

kmicinski

#lang racket

;; Notes, 1/22
;; f is a function from α → bool (i.e., a predicate)
;; l is list of αs
;; we return the number of elements in l such that
;; they satisfy the predicate f

;; (count even? '(0 1 2 3 4)) ;; => 3
#;(define (count f l)

kmicinski

#lang racket

;; CIS352 'S26 -- 1/29 through 2/3

;; □ -- More practice with lambdas
;; □ -- Mapping
;; □ -- Explaining recursion and why it matters
;; □ -- Our first non-list recursive type: trees
;; □ -- Pattern matching

kmicinski

#lang racket

;; CIS352 'S26 -- 1/29 through 2/3
;; (There is a lot of material here, we will not cover it all today.)
;; □ -- More practice with lambdas
;; □ -- Mapping
;; □ -- Explaining recursion and why it matters
;; □ -- Our first non-list recursive type: trees
;; □ -- Pattern matching

kmicinski

#lang racket

;; Project 0 Tic-tac-toe with Racket
;; 
;; Please immediately read README.md

(provide board?
         next-player
          valid-move?
          make-move

kmicinski

#lang racket

;; Define a function that evaluates to #t if
;; the list l contains the number 7
;;
;; - what do we do when l is '()
;; - what do we do when l is (cons hd tl)
(define (contains-7 l)
  (if (empty? l)
      #f

kmicinski

#lang racket

;; Notes, 1/22
;; f is a function from α → bool (i.e., a predicate)
;; l is list of αs
;; we return the number of elements in l such that
;; they satisfy the predicate f

;; (count even? '(0 1 2 3 4)) ;; => 3
#;(define (count f l)

kmicinski

#lang racket

(define x 22)

;; □ -- List introduction: literals, basic operations
'()
'foo
'(x y z) ;; homoiconicity -- the language uses the same
         ;; representation for syntax / expressions as it does
         ;; for data.