apd is an arbitrary-precision decimal package for Go.
https://godoc.org/github.com/cockroachdb/apd
- panic-free operation; use errors when necessary
- defined performance (speed of operations can be defined by, i.e., size of input and precision)
- accurate precision (an operation performed with requested precision will use enough precision during internal operations to achieve desired result)
Testing is done primarily with the suite from General Decimal Arithmetic, which contains thousands of tests for various operations.