ffi bindings for JavaScript's BigInt.
Note: There is also purescript-bigints, which wraps the BigInteger.js js library that emulated big integers before the arrival of BigInt.
purescript-js-bigints on the other hand provides close ffi bindings to the new native BigInt and therefore doesn't require an external npm dependency. This library is basically an adoption of purescript-bigints.
spago install js-bigints