Abstraction of numeric types that may be raised to a power using the exponentiation operator x ^ n which accepts an instance of Exponentiable as its first operand, and an exponent as its second operand.

function exp(Float x) => e^x;

The exponentiation operation should obey the usual index laws, including:

• x^0 == 1
• x^1 == x
• x^(-1) == 1/x
• x^(m+n) == x^m * x^n
• x^(m-n) == x^m / x^n
• x^(m*n) == (x^m)^n
• (x*y)^n == x^n * y^n

where 0 is the additive identity, and 1 is the multiplicative identity.

Note that in general, the type of the exponent may be different to the numeric type which is exponentiated. For example, a Rational number class might be a subtype of Exponentiable<Rational,Integer>, thus accepting only whole-number exponents.