New limited range type?

["Martin Dowie" <martin.dowie@btopenworld.com>]

Ok, as we're in "my favourite thing I'd like in Ada" season, here's mine...

I'd like to be able to declare integer/float/fixed/decimal types that are
limited, at both ends, and never raise exceptions, e.g.

   type Safe_Degrees is
      digits 6 limited range -180.0 .. +180.0;  -- new use of 'limited'

such that

declare
   A, B, C : Safe_Degrees;
begin
   B := 170.0;
   C := 50.0;
   A := B + C;
   -- A equals +180.0 after this statement
   ...
end;

We limit values like this all the time (we're not allowed exceptions)
and although we can write and instantiate generics to help, it's still
a pain.

Could even prove useful in things like SPARK?

Flames welcome! :-)