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

[Antoine Pitrou]

Le 21/08/2014 20:40, Nick Coghlan a écrit :
> On 22 Aug 2014 03:27, "Antoine Pitrou"
> <antoine at python.org
> <mailto:antoine at python.org>> wrote:
>  >
>  >
>  > Le 21/08/2014 12:15, Nick Coghlan a écrit :
>  >
>  >>
>  >> Given:
>  >>
>  >>      Sequence[Number]
>  >>      Sequence[Number|None]
>  >>
>  >> There's still at least three options for extending the syntax even
> further:
>  >>
>  >>      Sequence[Number](EXPR)
>  >>      Sequence[Number:EXPR]
>  >>      Sequence[Number,EXPR]
>  >>
>  >> You'd probably want to use strings at that point, for the same reasons
>  >> PyContracts does. For example:
>  >>
>  >>      Number,"N>0" # Positive number
>  >>      Sequence[Number,"N>0"] # Sequence of positive numbers
>  >>      Sequence[Number],"N>0" # Non-empty sequence
>  >
>  >
>  > All of those are horrible and un-Pythonic, though.
>  > Python has one of the most powerful and user-friendly function call
> syntaxes around, why reinvent something clearly inferior and alien?
>
> I don't think it's possible to have "Pythonic" design by contract

We're not talking about design by contract, we're talking about type 
annotations. "A list of X integers" isn't exactly an extremely 
complicated notion. We shouldn't need weird convoluted syntaxes to 
express it.

Regards

Antoine.