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#lang racket

;; Assignment 4: A church-compiler for Scheme, to Lambda-calculus

(provide church-compile
         ; provided conversions:
         church->nat
         church->bool
         church->listof)

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#lang racket

;; Midterm 2 -- Practice Solution

(foldr + 5 '(1 2 3))
;; call the lambda f
;; call the initial value i

(+ 1 (+ 2 (+ 3 5)))

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#lang racket

;; How to handle let and let*
(let* ([x 1]
       [y x])
  ((lambda (z) z) y))

(define (prim? s) (member s '(+ - * = equal? list cons car cdr null?)))
(define prim->op (hash '+ + '- - '* * '= = 'equal? equal? 'list list 'cons cons
                       'car car 'cdr cdr 'null? null?))

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;; Closure-Creating Interpreters in Racket
#lang racket

;; expressions comprise the λ-calculus extended
;; to include numeric constants and the + builtin
(define (expr? e)
  (match e
    [(? number? n) #t]
    [`(+ ,(? expr? e0) ,(? expr? e1)) #t]
    [(? symbol? x) #t]

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#lang racket

;; λ Calculus Exercises
;; Tue, Oct 25, 2022
;; CIS 352

;; Exercise 1:
;; ((λ (x) x) (λ (y) y))
;; Perform beta reduction on this term
;; For credit: the substitution must be made explicit

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#lang racket

;; λ Calculus Exercises
;; Tue, Oct 25, 2022
;; CIS 352

;; Exercise 1:
;; ((λ (x) x) (λ (y) y))
;; Perform beta reduction on this term
;; For credit: the substitution must be made explicit

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#lang racket
(provide (all-defined-out))

;;
;; CIS352 (Fall '22) -- IfArith Intro
;;

;; builtin functions
(define (function-name? fn)
  (member fn '(+ - / * mod == =0? not)))

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;; October 6, 2022
;; CIS352, Fall 2022
#lang racket

;; write the following in direct style
;; (i.e., perform recursive call, leave work
;; on the stack)

;; sum all elements in a list
(define (sum-list lst)

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;; CIS352 -- Fall 2022
#lang racket

;; An S-expression or "structured" expression
;; is a list-like piece of data
(define x '(this is (an (s) expression)))

;; we define the tree? data type
;;
;; algebraic data types are called "algebraic" because they are

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def take_first_n(lst, f, n):
    ret_lst = []
    for element in lst:
      if (n == 0):
        break
      if (f(element)):
        ret_lst.append(element)
        n = n - 1
    return ret_lst