Advantages of Functional Programming

"A pure function is a function in the mathematical sense; the result of its operation depends only on the input data. Evaluation of such a function involves nothing beyond the essential – variable values do not change, nothing is read or printed, no DB entries are made, and no requests to external services are issued."

In other words, it's useless? Some change must happen, there can not be a result if nothing changes. We can say that a result of a pure function is always a new value.

Without extremely complicated performance optimizations, writing such code is very inefficient.

Besides, instead of trying to find a way around the limitations of current architectures (poor parallelism), we should fix the architectures.