I have a function that maps a vector to a tuple. I would like to apply this to a matrix by rows, and get a tuple of vectors (`mapslices`

gives me a vector of tuples, I tried `zip`

but I could not get it working). MWE (inelegant, using the first element):

```
function maprows(f, A)
B = vec(mapslices(f, A, 1))
ntuple(i->map(x->x[i], B), length(B[1]))
end
f(x) = (x[1:2], x[3], x[4:5]) # number of elements is not necessarily 3
A = ones(10, 5)
C = maprows(f, A)
```

Notice that `C`

is a

```
Tuple{Array{Array{Float64,1},1},
Array{Float64,1},
Array{Array{Float64,1},1}}
```