Ada 95 Reference Manual
4.5.4 Unary Adding Operators
Static Semantics
The unary adding operators + (identity) and - (negation) are predefined for every specific numeric type T with their conventional meaning. They have the following specifications:
function "+"(Right : T) return T
function "-"(Right : T) return T
function "-"(Right : T) return T
NOTES
16 For modular integer types, the unary adding operator -, when given a nonzero operand, returns the result of subtracting the value of the operand from the modulus; for a zero operand, the result is zero.
