Support `Any` as an alias for `object` to describe a default typeclass implementation
anatoly-scherbakov opened this issue · 0 comments
anatoly-scherbakov commented
Context. In order to define a default implementation (the one used if no other implementation matches), we currently have to write something like this:
from classes import typeclass
@typeclass
def render(data_value) -> str:
"""Render a data value nicely."""
@render.instance(int)
def _render_int(data_value: int) -> str:
return f'This is an integer: {data_value}'
@render.instance(object)
def _render_int(data_value: object) -> str:
return f'No idea what this is: {data_value}'
assert render('BADOOM') == 'No idea what this is: BADOOM'
(this script should be runnable as-is.)
Decision. Support Any
as a special case to replace object
:
@render.instance(Any)
def _render_int(data_value: Any) -> str: # type: ignore
return f'No idea what this is: {data_value}'
Consequences.
- Pro: The code will look a little bit more straightforward;
- Contra:
mypy
with common settings might be unhappy aboutAny
being used, but that can be silenced withtype: ignore
I suppose.