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Re: Starting Forth 6.

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WJ wrote:

> WJ wrote:
> 
> > Brodie creates a defining word ARRAY, which creates a
> > two-dimensional array.  However, the words created by
> > ARRAY don't fetch values from the array or store values
> > in the array; they only return the addresses of array
> > elements.
> > 
> > Racket:
> > 
> > The following function returns a closure:
> > 
> > (define (array rows cols)
> >   (let ((the-vec (make-vector (* rows cols) 0)))
> >     (define (calc-index row col) (+ (* row cols) col))
> >     (case-lambda
> >       [(row col) (vector-ref the-vec (calc-index row col))]
> >       [(row col new-val)
> >        (vector-set! the-vec (calc-index row col) new-val)])))
> > 
> > (define board (array 4 4))
> > 
> > When called with 3 arguments, the third is placed in the array;
> > when called with 2 arguments, the value in the cell is returned.
> > 
> >   > (board 0 0 999)
> >   > (board 0 0)
> >   999
> > 
> > (for* ([row 4] [col 4])
> >   (board row col (+ col (* row 10))))
> > (for ([row 4])
> >   (for ([col 4])
> >     (display (~a (board row col) #:width 3 #:align 'right)))
> >   (newline))
> > 
> >   0  1  2  3
> >  10 11 12 13
> >  20 21 22 23
> >  30 31 32 33
> 
> Modified so that when the closure is called with no arguments,
> the entire vector is returned.
> 
> (define (array rows cols)
>   (let ((the-vec (make-vector (* rows cols) 0)))
>     (define (calc-index row col) (+ (* row cols) col))
>     (case-lambda
>       [(row col) (vector-ref the-vec (calc-index row col)) ]
>       [(row col new-val)
>        (vector-set! the-vec (calc-index row col) new-val) ]
>       [() the-vec])))
> 
> 
>   > (define board (array 4 4))
>   > (for* ([row 4] [col 4])
>     (board row col (+ col (* row 10))))
>   > (board)
>   '#(0 1 2 3 10 11 12 13 20 21 22 23 30 31 32 33)

Modified so that when the closure is called with one argument,
a row of the vector is returned.

(define (array rows cols)
  (let ((the-vec (make-vector (* rows cols) 0)))
    (define (calc-index row col) (+ (* row cols) col))
    (case-lambda
      [(row col) (vector-ref the-vec (calc-index row col)) ]
      [(row col new-val)
       (vector-set! the-vec (calc-index row col) new-val) ]
      [() the-vec]
      [(row)
       (vector-copy the-vec
         (calc-index row 0) (calc-index (add1 row) 0))])))

  > (define board (array 4 4))
  > (for* ([row 4] [col 4])
    (board row col (+ col (* row 10))))
  > (board 3)
  '#(30 31 32 33)

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Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-09-24 23:09 +0000
  Re: Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-09-24 23:36 +0000
    Re: Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-09-24 23:47 +0000
  Re: Starting Forth 6. "Ed" <invalid@invalid.com> - 2013-09-25 18:22 +1000
    Re: Starting Forth 6. "Elizabeth D. Rather" <erather@forth.com> - 2013-09-25 08:44 -1000
      Re: Starting Forth 6. hughaguilar96@yahoo.com - 2013-09-25 20:09 -0700
        Re: Starting Forth 6. albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-09-26 12:27 +0000
          Re: Starting Forth 6. "Elizabeth D. Rather" <erather@forth.com> - 2013-09-26 09:09 -1000
            Re: Starting Forth 6. hughaguilar96@yahoo.com - 2013-09-27 23:16 -0700
              Re: Starting Forth 6. the_gavino_himself <visphatesjava@gmail.com> - 2013-11-16 17:07 -0800
            Re: Starting Forth 6. "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2013-10-11 22:37 -0700
              Re: Starting Forth 6. the_gavino_himself <visphatesjava@gmail.com> - 2013-11-16 17:11 -0800
                Re: Starting Forth 6. "Stanley Daniel de Liver" <notagoodone@invalid.org.invalid> - 2013-12-11 16:49 +0000
          Re: Starting Forth 6. "Ed" <invalid@invalid.com> - 2013-09-27 11:39 +1000
            Re: Starting Forth 6. "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2013-10-11 22:39 -0700
          Re: Starting Forth 6. hughaguilar96@yahoo.com - 2013-09-30 16:47 -0700
          Re: Starting Forth 6. David Thompson <dave.thompson2@verizon.net> - 2013-10-12 18:22 -0400
            Re: Starting Forth 6. albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-13 12:17 +0000
        Re: Starting Forth 6. Whammo <sidciavic@gmail.com> - 2013-09-26 11:37 -0700
          Re: Starting Forth 6. hughaguilar96@yahoo.com - 2013-09-27 22:28 -0700
          Re: Starting Forth 6. "Clyde W. Phillips Jr." <cwpjr02@gmail.com> - 2013-10-11 22:34 -0700
    Re: Starting Forth 6. hughaguilar96@yahoo.com - 2013-09-25 19:58 -0700
  Re: Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-10-01 15:21 +0000
  Re: Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-10-12 09:17 +0000
  Re: Starting Forth 6. "WJ" <w_a_x_man@yahoo.com> - 2013-10-12 19:01 +0000

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