paradigms.md

Programming Paradigms

At this point, you may be wondering to yourself: what in the world does "programming paradigm" even mean? You're in luck. You're not the only one. Programming paradigms are just ways to classify programming languages according to their style.

There are a lot of different styles of programming, and a programming language isn't necessarily bound to one specific style. For now, let's talk about two opposite styles in Ruby, imperative and declarative.

Imperative Programming

The original style of high-level languages, imperative programming just feeds step-by-step instructions for the computer to execute.

def imperative_odds(array)
  idx = 0
  odds = []
  while (idx < array.length)
    if array[idx].odd?
      odds << array[idx]
    end
    i += 1
  end
  odds
end

Declarative Programming

In contrast, declarative programming describes what you want to achieve, without going into too much detail about how you're going to do it.

def declarative_odds(array)
  odds = array.select { |el| el.odd? }
end

The given examples are functionally the same, but are fundamentally different in style. Keep in mind, although programming languages like Ruby allow for different styles, certain languages restrict themselves to the guidelines of a specific programming paradigm. In the next reading, you'll find SQL is an example of declarative programming.

Additional Resources

• LMU overview of programming paradigms
• First part of Stanford lecture series