experiment with matrix-set-bang, some Rackety, fixing tests

collects/htdp/matrix-invisible.rkt

@@ -1,4 +1,4 @@
-#lang scheme
+#lang racket
 
 (require htdp/matrix-sig
          htdp/matrix-render-sig

collects/htdp/matrix-sig.rkt

@@ -1,4 +1,4 @@
-#lang scheme/signature
+#lang racket/signature
 
 ;; CONVENTION: 
 ;; [Rectangle X] = [Listof [Listof X]] 

collects/htdp/matrix-unit.rkt

@@ -1,4 +1,4 @@
-#lang scheme/unit
+#lang racket/unit
 
 (require htdp/matrix-sig
          htdp/matrix-render-sig
@@ -215,9 +215,30 @@
                        
                        [(>= j* j) (matrix-ref M (+ i* 1) (+ j* 1))])]))))
 
+#| from bug report 13264:
+
+I have two problems with matrix-set!. 
+
+1. When I enable matrix-set! 
+
+ (require htdp/matrix)
+ (define M (build-matrix 2 3 (λ (i j) (* (expt 2 i) (expt 3 j)))))
+ (matrix-set! M 1 2 'a)
+ (eq? (matrix-ref M 1 2) 'a)
+ (equal? M (build-matrix 2 3 (λ (i j) (* (expt 2 i) (expt 3 j)))))
+
+I get the results 'true' and 'true' -- the second one should NOT be true but false. 
+
+Because I can't change the snip either, M also displays wrong. 
+
+2. I really don't want to enable it in language levels strictly below ASL. 
+Otherwise the functional model breaks. ** But I do not know how to make teachpacks
+depend on the language into which they linked. ** 
+|#
+
 (define (matrix-set! M* i j x)
-  (define _ (when (is-a? M imatrix%)
-              (error 'matrix-set! "use functional updates instead")))
+  (when (is-a? M imatrix%)
+    (error 'matrix-set! "use functional updates instead"))
   (define-values (M n m) (check-matrix 'matrix-ref M* i j))
   (vector-set! (matrix-get-mat M) (+ (* i m) j) x)
   M*)

collects/htdp/matrix.rkt

@@ -1,4 +1,4 @@
-#lang scheme/gui
+#lang racket/gui
 
 ;; 4. integrate with snips
 

collects/htdp/tests/matrix-test.rkt

@@ -1,4 +1,4 @@
-;; The first three lines of this file were inserted by DrScheme. They record metadata
+;; The first three lines of this file were inserted by DrRacket. They record metadata
 ;; about the language level of this file in a form that our tools can easily process.
 #reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname matrix-test) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
 ;(require htdp/matrix-invisible)
@@ -50,7 +50,11 @@
 (check-expect (matrix-ref m1-minor 0 0) 'a00)
 (check-expect (matrix-ref m1-minor 0 1) 'a02)
 
-;; --- IMPERATIVE --- 
 (check-expect (matrix-ref m1 0 0) 'a00)
-;(define m1-modified (matrix-set! m1 0 0 'xxx)) ;; <-------- uncomment this and the test engine breaks
-;(check-expect (matrix-ref m1 0 0) 'xxx)
+;; --- IMPERATIVE ---
+;; see comment in matrix-unit.rkt
+;; ---------------------------------
+;; (define M-imperative (build-matrix 2 3 (λ (i j) (* (expt 2 i) (expt 3 j)))))
+;; (define M-modified   (matrix-set! M-imperative 0 0 'xxx))
+;; (check-expect (matrix-ref M-modified 0 0) 'xxx)
+;; (check-expect (matrix-ref M-imperative 0 0) 'xxx)