ollran
Pattern matching against arbitrary sized tuple
How can I pattern match against an arbitrary sized tuple? This works:
{status, _, _} = {:ok, 1, 2}
But what if I don’t know the structure of the tuple on the right side and I only care about the first element? This doesn’t work:
{status, _} = {:ok, 1, 2, 3, 4, 5, 6}
{status, _} = {:ok, {:random, :things}, [1, 2, 3]}
Is it possible to get the first value from the tuple with pattern matching?
Marked As Solved
NobbZ
No. A tuple is of fixed size.
You can either use status = elem({:ok, 1, 2, 3}, 0) or [status | _] = Tuple.to_list({:ok, 1, 2, 3}.
Also Liked
lpil
Tuple.to_list/1 will allocate a new list, Kernel.elem/2 can be used to retrieve the first element without creating this intermediate list 
glmeocci
I’d love it!
{:file_info, file_sieze | _the_rest_as_tuple} <- info
dkuku
would be handy to have some macro that generates the missing underscores:
{:ok, info} <- :file.read_file_info(pid),
{:file_info, file_size, _, _, _, _, _, _, _, _, _, _, _, _} <- info,
{:file_info, file_size, _escape_next(12)} <- info,
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