supply missing in metafunction

[haroldcarr]

subtract and subtract1 tests fail because in is missing.

Note: in is defined in redex-doc/redex/scribblings/long-tut/code/common.rkt --- but that file is used in a different part of the tutorial. At this point in the tutorial the only import is (require redex).

[wilbowma]

Is there a reason to redefine this instead adding an import from common.rkt?

[haroldcarr]

I would vote to putting the definition in place (rather then import) to keep the exposition self-contained up to that point. For someone new to redex it is useful to see it in isolation.

[wilbowma]

Aftering reading through the tutorial more carefully, I agree. Up to this point in the tutorial, common.rkt is not mentioned, and in just comes out of no where.

I'll merge this today if there are no objections.

[mfelleisen]

See #112