purescript-precise
This is a library for working with numbers of arbitrarily finite size.
JavaScript (and to some extension PureScript) has quite a few drawbacks when it comes to large numbers. For example, PureScript's Int primitive is a member of the Bounded typeclass, with top == 2 ^ 31 - 1 and bottom == - (2 ^ 32).
The PureScript Number primitive is not Bounded in the same way; however, there are problems with manipulating large-enough Numbers:
> import Prelude
> let x = 900000000000000000.0
> :t x
Number
> x + 1.0 == x
true
> x + 1.0
900000000000000000
In this library, correctness is prioritized above all else:
> import Data.HugeNum
> let x = fromNumber 900000000000000000.0
> let y = fromNumber 1.0
> x + y == x
false
> x + y
HugeNum 900000000000000001.0
Addition is implemented using an elementary-school method. Multiplication follows Karatsuba.
Installation
bower install purescript-precise
Documentation
Module documentation is published on Pursuit.