racket/collects/web-server/default-web-root/servlets/examples/compound/multiply.ss

87 lines
2.8 KiB
Scheme

(module multiply mzscheme
(require (lib "servlet.ss" "web-server")
(lib "etc.ss")
"helper.ss")
(provide (all-defined))
(define interface-version 'v1)
(define timeout +inf.0)
; matrix = (listof (listof num))
; matrix-multiply : matrix matrix -> matrix
(define (matrix-multiply a b)
(map (lambda (a-row)
(side-map (lambda (b-column)
(apply + (map * a-row b-column)))
b))
a))
; side-map : ((listof a) -> b) (listof (listof a)) -> (listof b)
(define (side-map f m)
(cond
[(null? (car m)) null]
[else (cons (f (map car m))
(side-map f (map cdr m)))]))
; ---
; get-dimentions : -> nat nat
; to ask for and return the number of rows and columns
(define (get-dimentions)
(values
(get-number "the number of rows in the first matrix")
(get-number "the number of rows in the second matrix")))
; get-matrix : nat nat -> matrix
(define (get-matrix rows columns)
(let ([b (get-matrix-bindings rows columns)])
(build-list
rows
(lambda (r)
(build-list
columns
(lambda (c)
(string->number (extract-binding/single (string->symbol (field-name r c)) b))))))))
; get-matrix-bindings : nat nat -> (listof (cons sym str))
(define (get-matrix-bindings rows columns)
(request-bindings
(send/suspend
(lambda (k-url)
`(html (head (title "Enter a " ,(number->string rows) " by "
,(number->string columns) " Matrix"))
(body (form ([action ,k-url] [method "post"])
(table ,(build-list
rows
(lambda (r)
`(tr . ,(build-list
columns
(lambda (c)
`(td (input ([type "text"] [name ,(field-name r c)])))))))))
(input ([type "submit"] [name "submit"] [value "Okay"])))))))))
; field-name : nat nat -> str
(define (field-name row column)
(format "x-~a-~a" row column))
; ---
; render-matrix : matrix -> html
(define (render-matrix m)
`(table
([border "1"])
. ,(map (lambda (row)
`(tr . ,(map (lambda (n)
`(td ,(number->string n)))
row)))
m)))
; main
(define (start initial-request)
`(html (head (title "Matrix Product"))
(body
(p "The matrix product is"
,(render-matrix
(let-values ([(r c) (get-dimentions)])
(matrix-multiply (get-matrix r c)
(get-matrix c r)))))))))