empty-scene is a stub

[stchang]

lang whalesong

(require whalesong/world)
(require whalesong/image)
(empty-scene)

Produces the error:
empty-scene: stub definition

Should I use something else?

[stchang]

It appears the error only occurs when I run with racket and not whalesong, so I believe this is not a bug. Sorry.

[soegaard]

The ideal is that a Whalesong program runs in both DrRacket and the browser.
Therefore the stub for Racket ought to import empty-scene from 2htdp/image .
(But the point is moot if the other image functions doesn't work in DrRacket either -
if so feel free to close this PR again)

[stchang]

I'm investigating this. I tried simply exporting functions from 2htdp/image to use when running in DrRacket, but it doesnt work because whalesong defines it's own color struct instead of using the one from 2htdp/image.

https://github.com/soegaard/whalesong/blob/master/whalesong/image/private/color.rkt

Anyone know why it needs to do this?

[vishesh]

Whalesong wont compile modules written with #lang racket, that is why it uses its own struct color. Same is with posn. We have to import struct depending we are compiling for JS or running as Racket program.