I have a list of matrices passed into a function. I want to vertically concatenate them into a single matrix. I used to be able to do this:
foo = [[1 2; 3 4; 5 6], [7 8; 9 10; 11 12]] A =  for m in foo A = [A; m] end
which, ok, is inefficient, but in this particular code I only have to do it once so I don’t care. And it has the advantage of being fairly readable and compact.
As of 1.0, this throws an error:
ERROR: DimensionMismatch("All inputs to vcat should have the same number of columns")
Actually, in the REPL the error is different:
ERROR: UndefVarError: A not defined
The preferred idiom appears to be something along the lines of:
foo = [[1 2; 3 4; 5 6], [7 8; 9 10; 11 12]] A =  for m in foo append!(A, m) end A = reshape(A, :, size(foo, 2))
…because append! doesn’t preserve the shape of multidimensional arrays. This is ugly. And it doesn’t work if foo is empty, or if the first element in foo is one-dimensional or if the elements in foo are scalars. Which, of course, means that now I have to write lots of error checking code, making this even uglier.
In this particular case I’d gladly trade efficiency for compactness. Is there a better way to do this?