Tuesday, December 5, 2017

A Taste of Functional Programming


  • Ignite an interest in those who have never explored functional programming before
  • Exposure to functional concepts
  • Use functional parts of your existing language of choice you've never used before 
  • Lead you to pursue a functional language more in-depth

Paradigm Evolution

  • Mathematics
  • Computer Science
  • Spawn of languages
    • functional
    • procedural
    • imperative
    • declarative
    • object-oriented programming

OOP Limitations

"We’re going to be living in a multicore, distributed, concurrent — all the buzz words — world. The conventional models we’ve been doing, the OO stuff… is not going to survive in that kind of environment." - Dave Thomas
"OOP promised a cure for the scourge of software complexity. …its weaknesses have become increasingly apparent. Spreading state all over the place leads to concurrency issues and unpredictable side effects." - Dave Thomas

Thinking in Functions

  • Functions
    • Easy to reason about
    • Reliable
    • Pure
      • Don't modify variables outside of scope
      • No side effects
      • Deterministic (reproducible results)
  • Data transformation
    • ie. Unix pipes - cat foo.log | grep bar | wc -l
  • No side-effects
    • Side effects are:
      • modifying state
      • has observable interaction with external functions
  • Immutability
    • Immutable data is known data
    • Data that is created is not changed
    • Copy and alter
      • compilers can perform optimizations because of this
      • garbage collectors are smart about this
  • Higher-order Functions
    • Functions can receive functions as arguments and return functions
  • Where is my for loop?
    • recursion
    • map, reduce, filter, reject, take, etc.

Some (impure and pure) functional languages

  • LISP
  • Scheme
  • Clojure
  • Erlang
  • Scala
  • Ocaml
  • Haskell
  • F#
  • Elm
  • Elixir


"Elixir is a dynamic, functional language designed for building scalable and
maintainable applications. Elixir leverages the Erlang VM, known for running low-latency, distributed and fault-tolerant systems, while also being successfully used in web development and the embedded software domain.
" - http://elixir-lang.org

Here is an out line of topics to come:

  • Anonymous functions
  • Pattern matching
  • Multi-bodied functions
  • Higher order functions
  • Side effects and state
  • Composition
  • Enumerables
  • Partial function applications
  • Recursion
  • Concurrency
  • Transitioning from OOP to functional

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