missing __traits(isArray, T)? what's the difference between __traits & std.traits? can we remove one to avoid dup?

[Adam D. Ruppe]

On Sunday, 6 June 2021 at 00:52:32 UTC, mw wrote:
> and want to try `__traits(isArray, T)` in my code, but the 
> compiler complains it's not there,

You can check is array with an is expression `is(T == E[], E)`.

> I read both can be used at compile time, I'm wondering is there 
> any difference between __traits & std.traits?

The original idea was that __traits would be the raw language 
built-in, then std.traits is the refined library interface.

std.traits uses some __traits, some is(), and some other 
miscellaneous techniques together under the hood.

tbh my personal view is to ditch std.traits and just teach people 
the pure language techniques.