blob: b6310a1044752b47a31944c2f485f61b9dd01702 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
#lang scheme
; ------------------------------------------------------------
; PROGRAM NAME: HW02.rkt
;
; DESCRIPTION: Second homework assignment for CSI310
;
; AUTHOR: Ben Burwell ; CS 310: Theory of Programming Languages
; Muhlenberg College
;
;; ---------
;; NAME: invert
;; DESC: takes a list of 2-lists (lists of length 2), and returns a list with each 2-list reversed.
(define invert
(lambda (l)
(map swap l)))
(define swap
(lambda (l)
(if (= 2 (length l))
(list (cadr l) (car l))
(display "Error"))))
;; TEST
(invert '((2 1) (4 3) (6 5))) ;; should return (1 2) (3 4) (5 6)
;; ---------
;; NAME: compose23
;; DESC: that takes 1, 2, or 3 procedures and composes them, as specified by the equation:
;; (compose f g h) = (compose f (compose g h))
(define compose23
(lambda funcs
(if (= (length funcs) 1)
(car funcs)
(if (= (length funcs) 2)
((car funcs) (cadr funcs))
(if (= (length funcs) 3)
((car funcs (cadr funcs) (caddr funcs))))))))
|
