kmicinski

#lang racket

;; CIS352 -- Fall 2023
;; Lambdas

;; first order function -- no functions as arguments
;; O(n^2) the way it's written -- an easier implementation
;; is not easy functionally, need a different representation 
(define (reverse lst)
  (if (empty? lst)

kmicinski

#lang racket

;; Recursion over lists
(cons 1 (cons 2 (cons 3 (cons 4 '()))))

;; more laboriously as ...
(let ([last-link (cons 4 '())])
  (let ([second-to-last-link (cons 3 last-link)])
    (let ([third-to-last-link (cons 2 second-to-last-link)])
      (cons 1 third-to-last-link))))

kmicinski

-- see cek.slog
def var := String

-- terms
inductive term : Type where
  | Ref : var → term
  | Lam : var → term → term
  | App : term → term → term
open term

kmicinski

#lang racket

;; CIS352 -- Spring 2023, 4/4 and 4/6/2023
;; Beginning to the Church encoding project

;; output
(define (lambda-calculus? e)
  (match e
    [(? symbol? x) #t]
    [`(lambda (,(? symbol? x)) ,(? lambda-calculus? e-body)) #t]

kmicinski

#lang racket

;; CIS352 -- Spring 2023, 4/4/2023
;; Beginning to the Church encoding project

;; output
(define (lambda-calculus? e)
  (match e
    [(? symbol? x) #t]
    [`(lambda (,(? symbol? x)) ,(? lambda-calculus? e-body)) #t]

kmicinski

;; CIS352 -- 2/28/23
#lang racket

(define x
  (hash "A" (set "B" "C")
        "B" (set "C" "A")
        "C" (set "B")))

(define (count-edges graph)
  (foldl

kmicinski

#lang racket

;; Interpreters, Feb 23

(define (arith-expr? e)
  (match e
    [(? number? n) #t]
    [`(,(? number? n0) + ,(? number? n1)) #t]
    [`(,(? number? n0) - ,(? number? n1)) #t]
    [`(,(? number? n0) * ,(? number? n1)) #t]

kmicinski

#lang racket

;; tail recursive functions
(define (filter f l)
  (define (h l acc)
    (match l
      ['() acc]
      [`(,hd . ,tl)
       (if (f hd)
           (h tl (cons hd acc))

kmicinski

#lang racket

(define x '(this (is an) s expression))

;; Write a function that takes an input list l
;; and adds 2 to every element of the list
;; assume all elements are numbers
#;(define (add-two-to-each l)
  (define addtwo (lambda (x) (+ x 2)))
  ;(define (addtwo x) (+ x 2))

kmicinski

#lang racket

;; Thursday, Dec 8, 2022
;; Class 2 -- Type Inference
;; 
;; In this exercise, we will study type inference, and
;; a variety of type system features.

(provide (all-defined-out))