[Python-ideas] Proposal: Use mypy syntax for function annotations

[Steven D'Aprano]

On Wed, Aug 20, 2014 at 03:06:09PM +0100, Paul Moore wrote:
> On 14 August 2014 18:31, Steven D'Aprano <steve at pearwood.info> wrote:
> > opt-out and use something else:
> >
> > @use_spam_annotations
> > def frobnicate(x: spam, y: eggs)->breakfast:
>     ...
> Which reminds me. Why is mypy exempt from the general recommendation
> to only use annotations on functions that are tagged with a decorator?

That's the whole point of Guido's proposal: he wants to bless, not mypy 
precisely since that's an alternative implementation of Python, but 
mypy's syntax as the standard use of annotations. Since it will be the 
official standard, there's no need to flag it with a decorator, even if 
CPython will not itself do anything with those annotations.

If Guido's suggestion is accepted, any linter, editor, IDE, Python 
compiler, or other static tool will be entitled to assume that 
annotations are type hints, using the mypy-derived syntax, at 
least unless explicitly told not to.



-- 
Steven