Oh, sorry, I just re-read. Your example still requires `range` to return
distinct types, so that probably shouldn't work.
On Fri, Nov 12, 2021 at 4:52 PM Axel Wagner <axel.wagner...@googlemail.com>
wrote:
> The error message gives you a reason - there is no single underlying type.
> This works:
>
> type B []byte
> func Bar[T []byte|B](s T) {
> for range s {}
> }
>
> But yes, your example arguably should be made to work eventually. I would
> suggest filing an issue about that.
>
> On Fri, Nov 12, 2021 at 4:47 PM tapi...@gmail.com <tapir....@gmail.com>
> wrote:
>
>> This one doesn't compile either.
>> So the range operation doesn't support values of parameter types?
>>
>> type MyByte byte
>>
>> func Bar[T []byte|[]MyByte](s T) {
>> for range s {} // cannot range over s (variable of type T constrained
>> by []byte|[]MyByte) (type set has no single underlying
>> }
>>
>> On Friday, November 12, 2021 at 11:40:53 PM UTC+8
>> axel.wa...@googlemail.com wrote:
>>
>>> On Fri, Nov 12, 2021 at 4:29 PM tapi...@gmail.com <tapi...@gmail.com>
>>> wrote:
>>>
>>>> On Friday, November 12, 2021 at 11:10:17 PM UTC+8
>>>> axel.wa...@googlemail.com wrote:
>>>>
>>>>> `range s` works differently for string and []byte. In the former case
>>>>> it iterates over utf8-encoded unicode codepoints, in the latter it
>>>>> iterates
>>>>> over bytes.
>>>>>
>>>>
>>>> It is true, but why it matters here?
>>>>
>>>
>>> Because it makes `range` different operations for the purposes of
>>> determining the allowed operations on a type-parameter.
>>>
>>>
>>>>
>>>>
>>>>>
>>>>> On Fri, Nov 12, 2021 at 3:18 PM tapi...@gmail.com <tapi...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>>
>>>>>> func Bar[T []byte|string](s T) bool {
>>>>>> for _, v := range s { // cannot range over s (variable of type T
>>>>>> constrained by []byte|string) (T has no structural type)
>>>>>> if v > 100 {
>>>>>> return true
>>>>>> }
>>>>>> }
>>>>>> return false
>>>>>> }
>>>>>>
>>>>>> The message is quite confusing.
>>>>>>
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>>>>>>
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>>
>
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