Error with define in Racket

Question

I just discovered Racket a few days ago, and I\'m trying to get more comfortable with it by writing a little script that generates images to represent source code using #l

Answer 1

As GoZoner explained, you can't use define in an expression context.

What could you do instead?

Use let:

(if (list? code)
    (let ([x '()])
      x)
    ...

Or it would work with an "empty" let and define:

(if (list? code)
    (let ()
      (define x '())
      x)
    ...

But that's a bit silly.

Or use cond and define:

(cond [(list? code)
       (define x '())
       x]
      ...

This last way -- using cond and define -- is closest to what the current Racket style guide recommends.