`Data.Decimal.Decimal` is quite close to Java's `BigDecimal` in intent but not quite the same: Java's `BigDecimal` has a 32-bit signed exponent whereas Haskell's `Decimal`'s exponent is 8-bit and unsigned. The difference shouldn't matter for the purposes of tracking money since accountancy rules are generally designed to prefer (carefully specified) rounding over keeping track of numbers with hundreds of decimal places.