Re: [Haskell-cafe] What is a safe Haskell data type to store and manipulate Money values?

Am 04.04.2017 um 17:10 schrieb David Turner:

On 4 April 2017 at 15:50, Joachim Durchholz mailto:jo@durchholz.org> wrote:

Am 04.04.2017 um 16:13 schrieb ALeX Kazik:

Rational?

You'd be constantly be doing explicit calculations to get back to a denominator of 100. Plus you'd have to deal with those cases where the denominator is a divisor of 100, and you'd need explicit nonstandard conversion to strings.

The same sort of fiddling-the-denominator problems also occur if you use `Decimal` - it's not normally useful to be able to represent things smaller than £0.01 (or whatever the smallest unit of your local currency is); I'd even go as far as to say it's useful to be able to be sure that you _can't_ represent such things (in the domain of basic accounting at least - more complex things may deal with smaller fractions of currency, so YMMV etc).

Decimal has a roundTo function, Rational does not.