Yes that too. To differentiate between MinFloat and MinInt for instance.
:)
On Thu, Mar 25, 2021, 8:18 AM Martin Leiser <leiser.1...@gmail.com> wrote:
>
>
> Ian Lance Taylor schrieb am Dienstag, 23. März 2021 um 23:22:51 UTC+1:
>
>> On Tue, Mar 23, 2021 at 3:19 PM atd...@gmail.com <atd...@gmail.com>
>> wrote:
>> >
>> > Since, we also know the type of v, It would be infered from it.
>> >
>> > There is no variance, no dependent type... Meaning that the type of a
>> Go variable does not change.
>> > So the constraints do not change midway through the program, including
>> type names/definitions.
>> >
>> > It does however require to have something that resemble a type
>> definition beforehand.
>> > A type parameter definition.
>>
>> In some cases it can be inferred.
>
>
> But even if it can be inferred it should be possible to annotate the type
> I do expect,
> to improve local readiblity and compile time error message quality:
> I assume that "x" is later used in a context requiring the type to be
> "int":
> x := Min(someFunc(foo), someFunc(bar))
> Here i can use:
> var x int = Min(someFunc(foo), someFunc(bar)))
> but using
> x := Min[int]( someFunc(foo), someFunc(bar)))
> The three version yield different error message, if the called function
> "someFunc()" return a float instead of the expected int.
>
> But what about cases where it
>> can't? And what if I want to write
>>
>> // IntMin is a function with type func(int, int) int.
>> var IntMin = Min[int]
>>
> ?
>>
>> The constraints don't change midway through a program, but in your
>> example the meaning of T does change.
>>
>>
> hmmm... if all I need throughout my whole package is one binding e.g. to
> "int",
> or to the type parameter "MyParameterType" my function use for themselves
> it may get teadious to
> repeat the [MyParameter] all over the place.
> Type inferences helps, but weakens the quality of error messages.
> So please always allow for a explicit type parameter annotation even if
> inference is possible.
> (And doing so in a more global location may improve simplicity a lot;-)
>
> Martin
>
>> Ian
>>
>>
>> > On Tuesday, March 23, 2021 at 10:41:15 PM UTC+1 Ian Lance Taylor wrote:
>> >>
>> >> On Tue, Mar 23, 2021 at 2:17 PM atd...@gmail.com <atd...@gmail.com>
>> wrote:
>> >> >
>> >> > Quick question...
>> >> >
>> >> > Why do we need brackets to define a parametered function, struct
>> etc...?
>> >> >
>> >> > Why not change Go kinds to accept either a type (would produce a
>> regular, function, structs, etc) or a new type parameter object that would
>> implement the constraints (would produce a generic function definition)
>> >> >
>> >> > for instance,
>> >> >
>> >> > type parameter T
>> >> >
>> >> > // [...] some way to add constraint to T
>> >> >
>> >> > func Max(v T) T{...}
>> >> >
>> >> > What are the brackets for? Just an idea.
>> >>
>> >> Each call to Max can use a different value for T. We can call
>> >> Max[int] and Max[string]. How would we do that with this notation?
>> >>
>> >> A type parameter really is a parameter to the function. Making it
>> >> syntactically similar to other non-type parameters seems like a good
>> >> idea to me.
>> >>
>> >> Ian
>> >
>> > --
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>>
>>
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