No apparent way to access the tuple size/index as a literal

[CraftSpider]

I find this macro handy for tuple implementations, but have bumped into two related issues:

1. Accessing the tuple size as a literal. This is useful if one wants, say, an array of the same size as the elements in the tuple as a type
2. Accessing the current tuple index as a literal in a repetition. Basically, the ability to print out 'accessing tuple index N'

[bkchr]

Hey, do you have any ideas how the syntax could look for each of them?

[CraftSpider]

If nothing nicer, may be possible to support #length in for_tuples and #index in repetitions.