[generics] (again). Type inference is somewhat weak

[Denis Cheremisov]

https://go2goplay.golang.org/p/ObL79WVHDjw

Need to write types explicitly although all the info needed is easily accessible:

fmt.Println(IsOK(*commonResponse, *commonError)(r))

What I am sure is I will keep using a code generator instead of this monstrosity. 

[Denis Cheremisov]

Better example. A method to request for exacly one element from the gRPC bistream. A thing that is frequently needed when there're lots of bistream gRPC methods.

https://go2goplay.golang.org/p/RQEyhRRQb0p

IRL I would need to call it as

resp, err := proto.ReadOne(service.Service_MethodClient, service.MethodRequest, service.MethodResponse)(ctx, client.Method, &service.MethodRequest{

    …

})

instead of simple to read

resp, err := proto.ReadOne(ctx, client.Method, &service.MethodRequest{

    …

})

среда, 17 июня 2020 г., 19:43:35 UTC+3 пользователь Denis Cheremisov написал:

[roger peppe]

Yes, I agree. It seems to have trouble inferring types when the argument is a generic interface type.

Here's a simpler example: https://go2goplay.golang.org/p/3-aVhD6Y9R2

I think this is probably https://github.com/golang/go/issues/39661

  cheers,

    rog.

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[Ian Lance Taylor]

On Thu, Jun 18, 2020 at 12:23 AM roger peppe <rogp...@gmail.com> wrote:
>
> Yes, I agree. It seems to have trouble inferring types when the argument is a generic interface type.
> Here's a simpler example: https://go2goplay.golang.org/p/3-aVhD6Y9R2
> I think this is probably https://github.com/golang/go/issues/39661

Is this related to
https://go.googlesource.com/proposal/+/refs/heads/master/design/go2draft-type-parameters.md#type-inference-for-generic-function-arguments
?

Ian