[racket] Temporary Definitions with ellipses

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Tue May 24 16:54:35 EDT 2011

On May 24, 2011, at 2:25 PM, SCIAMACHIST wrote:

> Lewis Watmore
> Hello,
>    I am a "noob" so if this is the wrong place for my question, please direct me to somewhere more appropriate.
>    In the DrScheme Companion at "3.3 Finger Exercises on Composing Functions" it is stated that you can create temporary definitions using an ellipsis in this manor:
>    (define (feet->yards f) ...)
> --where the ellipsis "is a legal Scheme name. DrScheme does not attempt to determine the meaning of a name until necessary."
> But DrRacket does not allow this usage. I get this error message: "...: ellipses not allowed as an expression in: (...)"
>    Is there an alternative other than commenting-out unfinished definitions?

The Companion is for people who work their way through How to Design Programs (1e or 2e). As stated in the Companion, they are expected to use the HtDP student languages, which support this notation. See attached screenshot. 

You may also wish to look at 


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