Add at-TypedDict macro

[tonyhffong]

No description provided.

[tonyhffong]

@StefanKarpinski @simonster , anyone ?
I start thinking I'm proposing something really dumb ...

[stevengj]

Looks good to me. We definitely need something like this.

[StefanKarpinski]

This seems fine to me. Does the syntax seem good – first pair is the types?

[simonster]

Maybe this ship has already sailed on this, but I wonder whether it might be better to have a macro that just makes the 0.4 syntax work everywhere, so you'd write:

@compat Dict(a=>1, b=>2)

or something like that. AFAICT this can still be parsed on 0.3.

[StefanKarpinski]

Seems hard to implement since that's then one huge @compat macro.

[stevengj]

Doesn't seem that bad to me... the @compat macro could call subsidiary functions, after all. (It could dispatch on the first symbol it encounters.)

In the present case, I'd prefer Compat.Dict{Foo,Bar}(foo=>bar), but that is not a valid macro syntax. @simonster's proposal, however, would allow @compat Dict{Foo,Bar}(foo=>bar)

[simonster]

I'm not too concerned about having one huge @compat macro unless we're making a huge number of breaking changes in a single release. But we could also have one macro per feature, i.e. @Compat.dict Dict(a => 1), @Compat.dict AnyDict(a => 1), and @Compat.dict Dict{K,V}(a => 1). It's only a little more verbose, the syntax is closer to the real 0.4 syntax, and you can just remove the macros once 0.4 is out.

[stevengj]

I would strongly prefer a single @compat macro.

[StefanKarpinski]

Why?

[stevengj]

Because it is much clearer, shorter, and easier to remember: you use the Julia-master syntax, and just stick @compat in front. And when backwards compatibility is no longer necessary, you just delete @compat.

It also has the virtue of acclimating the programmer to the Julia-master syntax, as well as being instructional for anyone reading the code.

[StefanKarpinski]

Those are all good reasons. Seems like the way to go.

[tonyhffong]

That's much better. I'm closing this one. Thanks.