MapEntry

[Hixie]

I like the general direction of https://github.com/munificent/ui-as-code/blob/master/ideas/control-flow-elements.md. One random idea to throw out is whether maybe MapEntry would be a useful class to use in the case of map literals containing control flow. It would let you easily call into other methods and get back name/value pairs; currently, it's not clear how you would programmatically control the name side.

If the language supported tuples, this would also be a place to use those.

[munificent]

Oh, that is an interesting idea. That opens up some questions around whether you could use ... to spread a List into a map literal too.

My general impression is that MapEntry is rarely used, so this probably isn't worth the extra complexity. But it might be. I agree that tuples would be a natural fit if we had those. (I think Lasse also feels that if we had tuples, MapEntry would no longer need to exist except for compatibility reasons.)

[tatumizer]

Map may be retrofitted with a constructor with vararg list of MapEntries:
Map.fromEntries(MapEntry<K,V> entries...)

Then it will be possible to write (see the discussion in #15)

var map = Map.fromEntries {
  +MapEntry("foo", "bar");
  if (cond) {
    +MapEntry("baz", "haha");
  }
}