(debug-repl) will fail if immutable top-level variable is shadowed by a local variable

[florence]

In:

#lang racket
(require debug/repl)
(define x 10)
(define (f x)
  (+ x (debug-repl)))

Running (f 10) results in:

namespace-set-variable-value!: assignment disallowed;
 cannot re-define a constant
  constant: x

[AlexKnauth]

This is an interesting failure. Do you have any idea if I can create a namespace with a shadowed version?

[florence]

I don't know of one. I tried to make one so that resume function I'm implementing florence@b6c2266 could property reset the namespace, and couldn't figure out a way to do it with namespaces.

Maybe the REPL could use a custom #%top that looks in some hash table that has the information about local variable (basically vect from https://github.com/AlexKnauth/debug/blob/master/debug/repl.rkt#L36 ). This feels really ugly, but then again this is scary reflection land. This would have the side effect of fixing #5.

[AlexKnauth]

Oh! Ok, I'll try that this afternoon.

[AlexKnauth]

Wait, how do I add a #%top macro to a namespace? There's no namespace-set-syntax-transformer-value! as far as I know, and I don't want to rely on define-syntax being bound to the correct thing in the namespace.

[florence]

I would have a separate module that's something like:

#lang racket/base
(provide (rename-out [in:top #%top]))
... an implementation ...

then use dynamic-require to get it into the current namespace.

This still isn't great because it can't fall back to the modules #%top. Not sure of a good way around that...

[AlexKnauth]

Fixed by 11ce8f0