core.traits?

[H. S. Teoh]

On Mon, Jan 07, 2019 at 04:54:15PM -0500, Steven Schveighoffer via Digitalmars-d wrote:
> On 1/7/19 4:41 PM, H. S. Teoh wrote:
> > On Mon, Jan 07, 2019 at 01:25:17PM -0800, Manu via Digitalmars-d wrote:
> > [...]
> > > Perhaps AliasSeq should live somewhere different?  I'm feeling
> > > like a lean/trimmed-down core.meta might want to exist next to
> > > core.traits though; it seems reasonable.
> > 
> > I'm afraid this would set the wrong precedent -- since there's
> > core.traits for std.traits and core.meta for std.meta, why not also
> > have core.typecons, core.range, and then it's all gonna go downhill
> > from there, and before you know it there's gonna be core.stdio and
> > core.format... *shudder*
> 
> std.internal.traits contains pieces of std.meta -- a quick look shows
> it has AliasSeq (but under the name TypeTuple),

What, wut...?  `TypeTuple` still exists?! I thought we had gone through
a somewhat painful deprecation cycle just to kill it off. Or is that
cycle not done yet...?


> allSatisfy, anySatisfy, Filter, staticMap. We might as well just move
> the whole thing there.

I dunno, IMO allSatisfy, anySatisfy, and esp. Filter and staticMap are
all heavy-weight templates (not in terms of code complexity, but in the
sheer amount of templates that will get instantiated when you use them,
AKA compiler slowdown fuel).  I'm not so sure they should go into
druntime.


> The fear of moving other pieces is real, but only if you look
> superficially.  traits and meta are really part of the language, I
> can't imagine using D without it (and neither can any of the people
> who put pieces of those modules into druntime).

Actually, I find myself redefining AliasSeq locally with a shorter name
all the time.  Scarily enough, doing that is shorter than typing `import
std.traits : AliasSeq;`.


> I don't want to see anything more complex and interdependent get
> sucked in.  I know the goal for Manu right now is emplace, which does
> feel like a language feature. But as has been said many times here,
> std.traits is a no-brainer, and std.meta is really a building block
> that std.traits uses.
[...]

Wait, so you're saying we should move the *entire* std.meta and
std.traits to druntime...?


T

-- 
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