kmicinski

#lang racket

;; CIS 352 -- Spring '25
;; March 18, 2025

;; This week in class:
;; [ ] λ-calculus refresher
;; [ ] λ-calculus β reduction motivation
;; [ ] Extending the λ-calculus with numbers
;; [ ] Building an interpreter with closures

kmicinski

#lang racket

;; CIS352 -- Feb 25, 2025

;; How do you calculate the transitive closure of a graph given using
;; the layout we've discussed?
;;
;;

;; Let's define a function `(step gr)`, which take a graph as

kmicinski

#lang racket

;; Algebraic Data II
;; 
;; CIS352 2/6/25

;; Note: for this lecture I am transliterating some very nice
;; notes from https://abhiroop.github.io/Haskell-Red-Black-Tree/
;; (written by Abhiroop Sarkar)

kmicinski

#lang racket

;; 0 argument function which calls itself
;; (with zero arguments...)
(define (loop) (loop))


(if #t 42 (loop))

;; if cannot be a function, because if it were,

kmicinski

use std::collections::{HashMap, HashSet};

type Clause = Vec<i32>;
type Clauses = HashSet<Clause>;
type Trail = Vec<TrailEntry>;
type Assignment = HashMap<i32, bool>;

#[derive(Debug, Clone)]
enum TrailEntry {
    Decision(i32),

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fn run(clauses: &Clauses) {

let mut state = DpllState::Running(Vec::new(), Assignment::new(), clauses.clone()); loop {

match &state {

DpllState::Unsat => {

println!("UNSAT"); break;

} DpllState::Sat(trail) => {

println!("SAT {:?}", trail);

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;; Traditional Abstract DPLL (no clause learning)
;; See this paper: https://homepage.cs.uiowa.edu/~tinelli/papers/NieOT-JACM-06.pdf
#lang racket

(define (clause? cl)
  (match cl
    [`(,(? integer? x) ...) #t]
    [_ #f]))

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)

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;; 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)))