Experimental Human Factors Take on Functional Programming

As a functional programmer, one often takes the productivity advantages of functional programming as an article of faith: Versus imperative and object-oriented counterparts, functional programs must be shorter, more robust, quicker to develop, and easier to maintain. Designers of programming languages and compilers harp on the supposed benefits of their languages and implementations. But when it comes down to it, where is the evidence? There is admittedly a lot of problems when forming a rigorous question and experiment to compare languages. An empirical study is even more difficult because there are really few large software systems that are implemented equivalently in multiple languages. Still, there turns out to be a few studies on the productivity and usability side of functional languages and mixed paradigm languages (e.g., Pankratius et al's "On the Benefits of Combining Functional and Imperative Programming for Multicore Software"). The results appear to be quite consistent: functional programs are shorter but they aren't any quicker to develop for even relatively skilled programmers. Performance is generally found to be on par. Moreover, fancy type systems have the disadvantage in that they could complicate the programmer's understanding of the program and prolong the debugging process.