Code - Functional programming (FP) - Collection Operations

Functional programming (FP) defines standard operations on collections.

It is a declarative paradigm that treats computation as the evaluation of mathematical functions.

Most of the operations, you perform on collections can be accomplished with five simple functions:

• map
• filter
• mergeAll
• reduce
• zip

These five functions hold a key to simplifying asynchronous programming and avoiding race conditions, propagating and handling asynchronous errors, and sequence events and requests.

With functional programming (FP), the code is organized around:

• pure functions that take data and transform it, without modifying any shared state.
• around how data flows between these pure functions to produce output data.

In other words, the application of several function programming operations creates a composite type called a Algebraic data type

In the same vein that SQL,

• some operation defines a logical plan (meaning that you build a metadata object, there is no data movement)
• some operation triggers the execution (generally known as the terminal operation).

Multiple invocations of a function at different points in time will always return the same output as long as the input remains the same. It makes it easy to understand and predict the behavior of the program.

imperative vs Functional ¹⁾

• Functional Programming - Sum
• Functional Programming - flatMap

JVM based Functional Programming Languages

• Scala
• Clojure
• Groovy

• ReactiveX - ReactiveX: A library for composing asynchronous and event-based programs using observable sequences for the Java VM, Javascript
• https://ramdajs.com/ - Javascript

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