What is Functional Programming?

• It is a code-crafting philosophy that emphasizes purity, immutability and functions as first-class citizens.
• Code is broken down into small, reusable functions that focus on "what" to do rather than "how" to do it, making it easier to reason about and test.
• Data is treated as immutable, meaning it cannot be changed after creation, leading to more predictable and less error-prone code.

Is it required?

• Dart is a multi-paradigm language, meaning it supports both OOP and FP approaches. But FP concepts bring benefits in terms of code clarity, maintainability and testability.

How to do it in Dart?

• Traditional Ways

  1. Top Level Functions

     → They exist outside of classes, directly at the file level.

     • Example

  2. Anonymous Functions

     1. Lambda

        → Lambda functions are – nameless, one-liner heroes who simplify code with concise power.

        • Example

     2. Closures

        → It is a magician with a photographic memory.

        → A function that magically remembers its surrounding environment, even after the party's over.

        • Example

  3. Extensions

     → It infuses existing classes with extra powers, making them even more versatile.

     • Example

• Modern Ways

  → These are introduced in Dart v3

  1. Records

     → Records are like Lego for data: lightweight, flexible, and perfect for crafting concise and efficient data models.

     1. Multiple Return Value

        (String, String) getName() {
        
          var firstName = 'John';
          var lastName = 'Smith';
        
          return (firstName, lastName);
        }
        
        void main() {
        
          final name = getName();
          print('${name.$1} ${name.$2}'); // John Smith
        }
        

     2. Destructing

        (String, String) getName() {
        
          var firstName = 'John';
          var lastName = 'Smith';
        
          return (firstName, lastName);
        }
        
        void main() {
        
        	final (firstName, lastName) = getName();
          print('$lastName $firstName'); // Smith John
        }
        

Packages

Functional Programming

→ dartz

→ fpdart

Immutability

→ fast_immutable_collections

→ kt_dart

→ built_collection

→ equatable

→ freezed

Resources

https://github.com/gerfalcon/fp_playground