What are (were) the most difficult parts of D?

[Basile B.]

On Thursday, 12 May 2022 at 15:31:03 UTC, Steven Schveighoffer 
wrote:
> On 5/12/22 11:18 AM, jmh530 wrote:
>> On Thursday, 12 May 2022 at 12:13:32 UTC, Basile B. wrote:
>>> [snip]
>>> ```
>>> is ( Type : TypeSpecialization , TemplateParameterList )
>>> is ( Type == TypeSpecialization , TemplateParameterList )
>>> is ( Type Identifier : TypeSpecialization , 
>>> TemplateParameterList )
>>> is ( Type Identifier == TypeSpecialization , 
>>> TemplateParameterList )
>>> ```
>>>
>>> I never remember those variants, because basically you never 
>>> need them...
>>> They were required for std.traits and that's it.
>> 
>> What's the difference between a Type and Type Identifier?
>
> Type is a type, Identifier is an identifier.
>
> In general, after such expressions, Identifier is now declared 
> as an alias to the type, if the is expression was true. But in 
> special forms, it might be a portion of the type.
>
> So e.g.:
>
> ```d
> static if(is(Foo Bar == struct))
> {
>   // inside here, it was determined that `Foo` was a type, and 
> it is a
>   // struct, and now, `Bar` is aliased to `Foo`
> }
> ```
>
> It's very confusing syntax though.
>
> -Steve

yess that kind of stuff