[racket] Stepper and application in BSL
On Aug 29, 2010, at 7:11 PM, Justin Zamora wrote:
> I put the following in my definitions window (Beginning Student Language).
>
> (define (f x)
> (+ x 1))
>
> (+ (f 3) 1)
>
> When I open the Stepper, (f 3) is highlighted in green, as expected.
> If I click "Step >", the expression changes to (+ (+ 3 1) 1), as
> expected (it stepped into the function). However, if I instead click
> on "Application >", I get "All of the definitions have been
> successfully evaluated." I expected to get (+ 4 1). I thought the
> stepper would replace (f 3) with the result of the application. Why
> didn't I see what I expected?
The "Application >" button jumps to the next step that reduces a function to its body. That is, one whose "green" expression is a call to a non-primitive.
Frankly, it looks to me like the "Application >" button could be demoted to a menu entry in the "jump to..." choice box.
John Clements
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