Real is:exact package:base set:included-with-ghc

Real numbers. The Haskell report defines no laws for Real, however Real instances are customarily expected to adhere to the following law:

• Coherence with fromRational if the type also implements Fractional, then fromRational is a left inverse for toRational, i.e. fromRational (toRational i) = i

The law does not hold for Float, Double, CFloat, CDouble, etc., because these types contain non-finite values, which cannot be roundtripped through Rational.

The types Ratio and Rational, and the classes Real, Fractional, Integral, and RealFrac.