The only difference between talking about "TypeDecl" and "TypeSpec" is,
that it distinguishes
type (
Foo int
Bar int
)
from
type Foo int
type Bar int
so I don't see how it helps and if anything it makes things more confusing,
because one type declaration can *actually* define multiple types, whereas
one type spec can only ever define exactly one type. By talking about type
declarations instead of type specs, you seem to imply that those two would
behave differently, which they don't.
So not only do I consider it more confusing, it also is completely
incorrect; Foo and Bar in both cases are distinct types and should be
distinct types. However, in the former case, they are two named types that
originate in the same type declaration so according to your proposed
language they would be identical.
Besides this, in fact, in the example you provide,
> https://play.golang.org/p/PmkcvdNQnx,
> there are two same (in texts) type declarations, they are both legal.
They are not the same, they are different. They are also in different type
specs. And if you where the insist to call the two type declarations the
same, then the type specs are "same" in exactly the same sense.
And why does "the same type-decl" will imply "type (Foo int; Foo int)", but
> "the same type-spec" will not make the imply?
Because both Foo are in the same type declaration, but not in the same type
spec. If the type spec language would imply anything of the sorts, it would
be that you could define two types in the same type-spec, which is clearly
impossible.
On Mon, Oct 3, 2016 at 11:10 AM, T L <tapir....@gmail.com> wrote:
>
>
> On Monday, October 3, 2016 at 4:59:26 PM UTC+8, T L wrote:
>>
>>
>>
>> On Monday, October 3, 2016 at 2:42:30 PM UTC+8, Axel Wagner wrote:
>>>
>>> Which would imply that something like this
>>> type (
>>> Foo int
>>> Foo int
>>> )
>>> might be legal. I don't understand (and thusly disagree) why that would
>>> be in any sense "less confusing".
>>>
>>
>>
>> I confuse again.
>>
>> In your before comments, you interpretate "the same type-spec" must be
>> the only occurrence of a type-spec, and can't be two occurrences of same
>> type-spec
>> in texts.
>> But now you interpretate "the same type-decl" can be two occurrences of
>> same type-decl in texts.
>>
>> I really don't know my English understanding is right or not, now, again.
>>
>
> Besides this, in fact, in the example you provide,
> https://play.golang.org/p/PmkcvdNQnx,
> there are two same (in texts) type declarations, they are both legal.
>
> And why does "the same type-decl" will imply "type (Foo int; Foo int)",
> but "the same type-spec" will not make the imply?
>
>
>>
>>
>>
>>>
>>> On Mon, Oct 3, 2016 at 7:26 AM, T L <tapi...@gmail.com> wrote:
>>>
>>>>
>>>>
>>>> On Monday, October 3, 2016 at 1:52:10 AM UTC+8, Marvin Renich wrote:
>>>>>
>>>>> * Matt Harden <matt....@gmail.com> [161001 23:34]:
>>>>> > I do think that T L has a point. The spec defines the syntax of the
>>>>> > language, and TypeSpec refers to a syntactical construct. It is not
>>>>> > possible in the syntax of the language to create two named types
>>>>> that
>>>>> > originate in the same TypeSpec. We seem to be saying that uint8 and
>>>>> byte
>>>>> > originate in the same "TypeSpec", but the "TypeSpec" referred to
>>>>> there is
>>>>> > an implementation detail of the compiler, not the syntactical
>>>>> construct
>>>>> > defined in the Language Specification.
>>>>>
>>>>> Does anyone remember if there was a time when TypeSpec was defined as
>>>>>
>>>>> TypeSpec = IdentifierList Type .
>>>>>
>>>>> instead of the current
>>>>>
>>>>> TypeSpec = identifier Type .
>>>>>
>>>>> This would give a clear reason why the wording under type identity is
>>>>> the way it is. I don't remember such a definition, and I've been
>>>>> following Go since before Version 1, but not since the beginning, so
>>>>> this is at least conceivable. It's also possible that the Go authors
>>>>> were considering such a definition, and part of the spec was written,
>>>>> but the idea was thrown out as unnecessary and adding extra
>>>>> complexity,
>>>>> accidentally leaving an artifact of a considered, but discarded,
>>>>> design
>>>>> detail.
>>>>>
>>>>> ...Marvin
>>>>>
>>>>>
>>>> I just checked the history of go spec: https://github.com/golang/go/c
>>>> ommits/master/doc/go_spec.html?after=mYQZV1%2BzTdUijP2zU6cxhOKduNorNTI0
>>>> It looks there is only one main change, from
>>>>
>>>> TypeDecl = "type" ( TypeSpec | "(" [ TypeSpecList ] ")" ) .
>>>> TypeSpecList = TypeSpec { ";" TypeSpec } [ ";" ] .
>>>> TypeSpec = identifier Type .
>>>>
>>>> to
>>>>
>>>> TypeDecl = "type" ( TypeSpec | "(" { TypeSpec ";" } ")" ) .
>>>> TypeSpec = identifier Type .
>>>>
>>>> so go authors may really think "T0 and T0" is worth mentioning in go
>>>> spec.
>>>>
>>>> BTW, I think it would be less confusing if "originate in the same
>>>> TypeSpec <https://golang.org/ref/spec#Type_declarations>" changed to
>>>> "originate in the same TypeDecl".
>>>> <https://golang.org/ref/spec#Type_declarations>
>>>>
>>>>
>>>>
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>>>
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