Apex is a pure object-oriented lanuage, and it does not provide any builtin features to make functional programming easier. The biggest obstacle in Apex is that functions(methods) are not First Class Citizens, the building blocks in a functional world. R.apex aims to pave the way for functional programming, and makes every attempt to mimic the functional features in Apex as much as possible. So we can adopt a functional paradigm based on R.apex.
R.apex offers a ton of utitlies on Apex collections like lists, sets and maps, to help you handle daily coding tasks.
R.apex provides support to Func objects, which paves the way for functional programming in Apex.
By adopting functional paradigm, R.apex is inherently built with function composition in mind.
If you are familiar with functional programming, it takes you only minutes to pick up R.apex.
If you are not, you can also use simple functions that you understand. It's just a utility library, and you decide how much you apply it.
R.apex honors the style of function call chaining, which greatly improves usability and code readability.
R.apex has various functions available to support collection manipulations.
R.apex provides a rich set of tools to help you compose functions to reuse your code.
