ASH has no syntax for initializing a composite variable like that; the right-hand side of the equals has to evaluate to an "expression".
Arrays and records, at least, would be very useful. I can also imagine syntax for maps - multiple key/value pairs - although since you can have multi-dimensional maps - maps of maps of ... - that might end up getting obscure.
Parser.parseVariable() is the method that would need to be modified.
Feel free to make a Feature Request - but don't hold your breath waiting for it to be implemented.