Compiler strips away parentheses affecting precedence in output code

[bodil]

Given the following function:

bug :: Number -> Number -> Number
bug a b = 0 - (a - b)

The compiler strips away the parentheses, yielding JS code like this:

return 0 - a - b;

I was expecting this:

return 0 - (a - b);

The former returns an unexpected result:

bug 0 (-2)
-- returns 2 ((0 - 0) - -2), not -2 (0 - (0 - -2)) as one would expect