Re: [go-nuts] [generics] cannot use generic type list.Element(type TElem) without instantiation
On Wed, Jul 1, 2020 at 8:22 PM Andrey T. wrote:
>
> continuation question -- does `type intElement list.Element(int)` introduce a
> new type just like `type myInt int` does? If so, in a previous example, these
> 2 maps are not of the same type, am I right?
Yes, "type intElement list.Element(int)" introduces a new type. You
can avoid introducing a new type by using a type alias: "type
intElement = list.Element(int)".
Ian
> On Wednesday, July 1, 2020 at 10:50:07 AM UTC-6, Ian Lance Taylor wrote:
>>
>> On Wed, Jul 1, 2020 at 9:39 AM wrote:
>> >
>> > Is this expected?
>> >
>> > import "list" // for 'std' list.go2
>> >
>> > func main() {
>> > type intElement list.Element(int)
>> > _ = make(map[int]intElement) // ok: compiles
>> >
>> > // nok
>> > _ = make(map[int]list.Element(int)) // cannot use generic type
>> > list.Element(type TElem) without instantiation
>> > }
>> >
>> > I don't think it is, but in case it is, how would I instantiate a
>> > make(map[int]intElement) without having to typedef a generic type before.
>>
>> From the parser's perspective the argument to make is an expression,
>> so in this case you need parentheses to keep this from looking like a
>> type conversion.
>>
>> make(map[int](list.Element(int)))
>>
>> Ian
>
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Re: [go-nuts] [generics] cannot use generic type list.Element(type TElem) without instantiation
Ian,
continuation question -- does `type intElement list.Element(int)` introduce
a new type just like `type myInt int` does? If so, in a previous example,
these 2 maps are not of the same type, am I right?
Thank you very much,
Andrey
On Wednesday, July 1, 2020 at 10:50:07 AM UTC-6, Ian Lance Taylor wrote:
>
> On Wed, Jul 1, 2020 at 9:39 AM >
> wrote:
> >
> > Is this expected?
> >
> > import "list" // for 'std' list.go2
> >
> > func main() {
> > type intElement list.Element(int)
> > _ = make(map[int]intElement) // ok: compiles
> >
> > // nok
> > _ = make(map[int]list.Element(int)) // cannot use generic type
> list.Element(type TElem) without instantiation
> > }
> >
> > I don't think it is, but in case it is, how would I instantiate a
> make(map[int]intElement) without having to typedef a generic type before.
>
> From the parser's perspective the argument to make is an expression,
> so in this case you need parentheses to keep this from looking like a
> type conversion.
>
> make(map[int](list.Element(int)))
>
> Ian
>
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Re: [go-nuts] [generics] cannot use generic type list.Element(type TElem) without instantiation
On Wed, Jul 1, 2020 at 9:39 AM wrote:
>
> Is this expected?
>
> import "list" // for 'std' list.go2
>
> func main() {
> type intElement list.Element(int)
> _ = make(map[int]intElement) // ok: compiles
>
> // nok
> _ = make(map[int]list.Element(int)) // cannot use generic type
> list.Element(type TElem) without instantiation
> }
>
> I don't think it is, but in case it is, how would I instantiate a
> make(map[int]intElement) without having to typedef a generic type before.
>From the parser's perspective the argument to make is an expression,
so in this case you need parentheses to keep this from looking like a
type conversion.
make(map[int](list.Element(int)))
Ian
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[go-nuts] [generics] cannot use generic type list.Element(type TElem) without instantiation
Hi,
Is this expected?
import "list" // for 'std' list.go2
func main() {
type intElement list.Element(int)
_ = make(map[int]intElement) // ok: compiles
// nok
_ = make(map[int]list.Element(int)) // cannot use generic type
list.Element(type TElem) without instantiation
}
I don't think it is, but in case it is, how would I instantiate a
make(map[int]intElement)
without having to typedef a generic type before.
PS: i'm using the latest commit at the time of writing in the dev.go2go
branch (6cf6bf162c)
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