One thing I seem to do a LOT in Java, Lua, Javascript is copy local variables to a same-named field of a record. Some kind of sane syntax to make that easier would be really nice.
Current approach:
f(a,b) = {a, b}
By not supplying a value, the value is copied from scope as a method.
Also the opposite - extract variables from an object into local variables:
{a,b} = {a = 1, b = 2} // Set a=1, b=2
To rename:
{foo = a, bar = b} = {foo = 1, bar = 2} // Set a=1, b=2