That;s pretty cool 
I’ll have to play with it a little bit to completely grasp it, thanks!
If any1 is actually using it, here’s an update. Using @tfwright & @ityonemo suggestions, I’ve got:
defmacro sigil_a(expr, _modifiers) do
{_, _, [key]} = expr
key = String.to_atom(key)
quote do
Map.fetch!(var!(socket).assigns, unquote(key))
end
end
