Shadowing

[sharkdp]

It would probably be beneficial if function parameters could shadow definitions from outer scopes, even unit names. For example:

>>> fn area(h: Length, w: Length) -> Area = h × w
error: identifier clash in definition
    ┌─ Module 'units::si', File /usr/share/numbat/modules/units/si.nbt:126:6
    │
126 │ unit hour: Time = 60 minutes
    │      ---- Previously defined here
    │
    ┌─ <input:1>:1:9
    │
  1 │ fn area(h: Length, w: Length) -> Area = h × w
    │         ^ identifier is already in use