redefining a function should be allowed

[doug-q]

when I use guppy in a notebook and I re-evaluate a cell containing a @guppy function definition I get an error:

guppylang.error.GuppyError: ('Module `main` already contains a definition named `rus`', None)

I suggest that instead, the existing function definition should be replaced

[mark-koch]

Should this behaviour be specific to notebooks or apply to all Guppy modules?

[doug-q]

Should this behaviour be specific to notebooks or apply to all Guppy modules?

I don't have an opinion. It does seem natural to always overwrite, but what are the costs? Do we check types etc inside the @guppy decorator, and overwriting invalidates those checks? If so, perhaps the current behaviour should remain possible.

Passing mod = GuppyModule(allow_overwrites=True) would be fine. One could write a wrapper around this that looked for a notebook environment if one were inclined.