It's a trade-off between speed and accuracy. Not all software deals with real-world engineering problems, and there are plenty of applications where you would p

It's a trade-off between speed and accuracy. Not all software deals with real-world engineering problems, and there are plenty of applications where you would prefer accuracy. I'd rather make that trade-off myself than have the language decide for me. Most of the time I would start with correctness and if speed is needed and the profiler shows that the bottleneck lies in fractional arithmetic, I'll switch to floating point numbers. A similar trade-off exists with bignums versus 32 or 64 bit integers. There again, I prefer a language that uses bignums by default. I'll convert the bottlenecks to use fixnums after I've verified that it is safe to do so.