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[Python-Dev] Please reject or postpone PEP 526

Steven D'Aprano steve at pearwood.info
Sun Sep 4 07:51:59 EDT 2016 
On Sun, Sep 04, 2016 at 12:31:26PM +0100, Mark Shannon wrote:

> In other words PEP 484 specifically states that annotations are to help 
> with type inference. As defined in PEP 526, I think that type 
> annotations become a hindrance to type inference.

I'm pretty sure that they don't.

Have you used any languages with type inference? Any type-checkers? If 
so, can you give some actual concrete examples of how annotating a 
variable hinders type inference? It sounds like you are spreading FUD at 
the moment.

The whole point of type annotations is that you use them to deliberately 
over-ride what the checker would infer (if it infers the wrong thing, or 
cannot infer anything). I cannot see how you conclude from this that 
type annotations will be a hindrance to type inference.

If you don't want to declare the type of a variable, simply DON'T 
declare the type, and let the checker infer whatever it can (which may 
be nothing, or may be the wrong type).



-- 
Steve
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