kmicinski

#lang racket

;; Direct style
(define (filter f l)
  (match l
    ['() '()]
    [`(,hd . ,tl) (if (f hd) (cons hd (filter f tl)) (filter f tl))]))

;; Tail recursive version
(define (filter-tl f l)

kmicinski

#lang racket
(provide (all-defined-out))
;;
;; CIS352 (Fall '24) Racket Warmup
;;

(define (square x) (* x x))

;; return the Euclidian distance between x0,y0 and x1,y1
(define (euclid-distance x0 y0 x1 y1)

kmicinski

;; Relational algebra
#lang racket

(define relation? symbol?)
(define atom? symbol?) ;; atomic lits are symbols

;; variables must be explicitly tagged, not 'x, but '(var x)
(define (var? x) (match x [`(var ,(? symbol? x)) #t] [_ #f]))
(define (var-or-atom? x) (or (atom? x) (var? x)))

kmicinski

;; Challenge: find all the bugs in this small functional compiler
#lang racket

(provide (all-defined-out))

(define verbose-mode (make-parameter #t))
(define i-am-a-mac (make-parameter #f))

;; 
;; Our compiler will have several layers

kmicinski

#lang racket
;; v0.0 April 8, 2024 -- WORKING NOTES (could have bugs!) 

;; Apply/Eval Refactoring -- Semantics Homework
;;
;; Kris Micinski ([email protected] and [email protected])
;;
;; Warning: may be buggy, please contact kris if you notice
;; obvious bugs.
(provide (all-defined-out))

kmicinski

#lang racket

;; The Church-encoded number N is represented as:
;; - A function (λ (f) ...) which takes a function f
;; - Returns a function which accepts an argument x
;;   and applies f N times to x

;; two, Church-encoded as a *Racket* lambda
(λ (f) (λ (x) (f (f x))))

kmicinski

#lang racket

;; The Church-encoded number N is represented as:
;; - A function (λ (f) ...) which takes a function f
;; - Returns a function which accepts an argument x
;;   and applies f N times to x

;; two, Church-encoded as a *Racket* lambda
(λ (f) (λ (x) (f (f x))))

kmicinski

#lang racket
;; CIS352 -- 3/19/2024

;; Exam Solutions

;; Version A

;; (1a)
(define (count-n lst n)
  (match lst

kmicinski

#lang racket

;; PRACTICE Midterm 1 solutions

;; Part (a) 

(define (mul-list l k)
  (if (empty? l)
      '()
      (cons (* (first l) k) (mul-list (rest l) k))))

kmicinski

#lang racket

;; Some example λ calculus terms in Racket
;; ID (identity) applied to ID 
;; ((λ (x) x) (λ (x) x))

;; can't run this, y is free--but I can still β reduce it
;;((λ (x) y) (λ (z) y))
;; ⟶β y <-- error, in Racket, because we don't know what y is