ProgramByDesign: Difference between revisions

Revision as of 16:12, 16 June 2010

Revision as of 17:57, 16 June 2010

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presented their work with students.

In 2010, [[Racket (programming language)|PLT]] gaverenamed theits namemajor programming language [[Racket (programming language)|Racket]]. toThe theirname for [[DrScheme]], the [[integrated development environment|IDE]], was changed to [[DrRacket]].

variant of [[Scheme]], and the name [[DrRacket]] to the [[integrated development environment|IDE]] known as [[DrScheme]].

==Functional Programming, Computing and Algebra==

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Here is an example:

<source lang="lisp">

(require 2htdp/universe)

(require 2htdp/image)

;; create an image from the current time

(define (create-image t)
(place-image APPLE 50 (* 10 t) SPACE))

;; names for basic images

(define APPLE (circle 3 '"solid" ' "red"))

(define SPACE (empty-scene 100 100))

(animate create-image)

;; --- run program run:

(run-simulation 100 100 1/22 create-image)

</source>

This four-lineshort program simulates an apple falling from the top to the bottom of a

small white canvas. It consists of three parts:

* a function definition for create-image, which is a one-line function in mathematics, assuming an algebra of images with place-image, circle, and empty-scene have been introduced;

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red dot is a little bit lower.

Finally the run-simulationanimate line displaysapplies the imagesgiven onfunction, a 100 x 100 canvascreate-image, at the

rate of 2228 imagesticks per second to 0, 1, 2, 3, and so on. That'sThe howresulting moviesimages are made.

displayed on the computer monitor at the same pace. That's how movies are made.

The background needed for such an example is little more than knowledge about making

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program consists of as many lines as the mathematics. Moving between the mathematics

and the program is thus straightforward. Better still, the meaning of the two are

the same. [[DrRacket]]'s algebraic stepper can illustrate how SchemeRacket evaluates the

program as if it were a sixth or seventh grade student, step by step, using plain

algebra.

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==TeachScheme! and choice of programming language==

While theThe name TeachScheme! appears to imply that this design recipe requires Scheme (now [[Racket (programming language)|Racket]]),

and is only usefulteachable with [[DrRacket]]. Neither conclusion is true, neitherhowever. The

the process nor the data axis of the design recipe require the use of [[Racket (programming language)|Racket]]. The

TeachScheme! members and their students have successfully applied the design recipe

in Assembly, C, Java, ML, Python, and other programming languages, not to speak of

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A part of the team has a grant from the National Science Foundation for conducting field tests in colleges

and high schools. Professional-development workshops took place in the summer of 2007, 2008, 2009, and (anticipated) 2010. This part of the project is dubbed ReachJava; the accompanying book is

tentatively titled "How to Design Classes."