Variable shadowing and priorities

[brice-morin]

Consider the following ThingML function:

function f(a : Integer) do
  var b : Integer = a - 1
  ...
  var a : Integer = 0
  ...
end

The parser does not complain, but yields a surprising result...

In b = a - 1, a refers to var a, which is declared afterwards. IMHO, it should refer to the parameter a of the function, since it has not been shadowed yet.... Anyway, I think:

• shadowing is dangerous and should not be allowed i.e., it should not be possible to declare var a if it has been previously declared in a variable or a parameter.
• in an action block, it should not be possible to refer to variables defined later on... action blocks being purely sequential...