Pure functions. The ideal in functional programming is what is known as pure functions.A pure function is one whose results are dependent only upon the input parameters, and whose operation ...

Not all functional programming functions need to be pure. As Functional Programming: Pure Functions explains, it is possible (and sometimes desirable) to “separate the pure, ...

The JavaScript method, Array.map(f) is a pure function in that it takes a function as a parameter. That last point about pure functions warrants further exploration. First-order functions vs. pure ...