Array{Any} when collecting chained generators

[CarloLucibello]

Collecting a generator works as expected

julia> collect(i for i=1:10)
10-element Array{Int64,1}:
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10

But if you chain it

julia> collect(chain(i for i=1:10))
10-element Array{Any,1}:
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10

What puzzles me is that eltype(i for i=1:10) == Any

[iamed2]

eltype(i for i=1:10) == Any is an issue, I think. But probably an issue for JuliaLang/julia. I figure there could be two solutions:

1. Something involving Base.return_types to do inference on the generator function in the general case

OR

2. Special case a generator which just returns the results of an iterator (I think this would need some parser attention, i.e., have the parser use identity instead of (x)->x so that we can dispatch on it after.

[yuyichao]

eltype(i for i=1:10) == Any is an issue,

It's not an issue.

1. Something involving Base.return_types to do inference on the generator function in the general case

And we shouldn't do this.

I think we just shouldn't rely on eltype in collect.

[iamed2]

I wasn't sure whether Base.return_types was fair game or not.

I was thinking up some @generated solution until I realized that I can tell collect to not rely on eltype fairly simply. This line solves things:

Base.iteratoreltype(c::Chain) = EltypeUnknown()

but we may not need it with #85 (reviewing performance for that now). We will.

[CarloLucibello]

fixed by #85

[iamed2]

No, it wasn't

[CarloLucibello]

ouch, sorry, did the wrong test, ranges instead of iterators

[iamed2]

That's okay :)