Problem running code in Ch.9 (170:33)

[alexgian]

I ran into this problem while following the book, typing into Dr. Racket.

Rather than clutter the page here, I have put my code up in this gist:
https://gist.github.com/alexgian/f02ba4f81685809bc9dba9a96a8784a1

Basically, I came across this error when trying to run 170:33

. . zero?: contract violation
  expected: number?
  given: 'unset-hyper-batch-revs

I thought it might be due to my using the built-in gradient-descent function, rather than the one pre-specified in 141:38, so I changed that, but I got almost the same error again, except it flagged a different hyper as "unset"

. . zero?: contract violation
  expected: number?
  given: 'unset-hyper-batch-size

I hope I got those the right way round, but you get the idea.

Predictably, the same problem occurs if I try to run adam-gradient-descent (174:44), which leaves me a bit stuck.

Any suggestions on what I could possibly be doing wrong?

Many thanks

(Excellent book by the way, having fun working through it, just what I needed!)

[alexgian]

OK, problem solved, sorry 'bout the noise.

It was due to my using the malt builtins for smooth, sampling-obj and gradient-descent, instead of the book's.
I had erroneously assumed that since they'd been finalised with red boxes in the text, they would be equivalent to what was provided by malt. Not so, apparently.

So, onwards...