kmicinski

#lang racket

;; Tuesday, April 8, 2025
;; CIS352

(define (λ-expr? e)
  (match e
    [(? symbol? x) #t]
    [`(lambda (,(? symbol? x)) ,(? λ-expr? e-b)) #t]
    [`(,(? λ-expr? e0) ,(? λ-expr? e1)) #t]

kmicinski

#lang racket

;; CIS352 -- P3 Builtins help
;;
;; I wrote up these notes based on some student meetings.
;; This project is intentionally a bit vague about how to
;; handle the builtins. That is because I want you to have
;; some ability to have the experience of figuring out how
;; you might want to engineer your own solution, considering
;; the various trade-offs.

kmicinski

#lang racket

;; Consider the folllowing λ-calculus expression, write
;; a reduction sequence where each β reduction in the
;; sequence uses CBV evaluation order 
((λ (x) x)
 ((λ (y) y) (λ (z) z)))

((λ (x) x)
 ((λ (z) (z z)) (λ (y) (y y))))

kmicinski

#lang racket

;; CIS352 -- March 20, 2025

;; For the past few lectures, we've talked about the idea of "in-context" β:
;; the idea that we can "just do all the βs." So for example:
((λ (b) b)
 (((λ (x) x) (λ (a) a))
  ((λ (y) y) (λ (z) z))))

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),

kmicinski

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);