Pros of Fantasy Land

• Provides a specification for algebraic structures in JavaScript
• Widely adopted by the functional programming community
• Allows for interoperability between different libraries

Cons of Fantasy Land

• More abstract and theoretical, which can be challenging for beginners
• Lacks concrete implementations, focusing primarily on specifications
• Requires additional libraries or custom implementations for practical use

Code Comparison

Fantasy Land (specification):

// Example of a Functor specification
const myFunctor = {
  map: (f) => myFunctor
};

Folktale (implementation):

const { task } = require('folktale');

const myTask = task((resolver) => {
  resolver.resolve(42);
});

Summary

Fantasy Land focuses on providing specifications for algebraic structures, while Folktale offers concrete implementations of functional programming concepts. Fantasy Land is more abstract and theoretical, making it suitable for library authors and advanced functional programmers. Folktale, on the other hand, provides ready-to-use implementations that are more accessible to developers looking to apply functional programming concepts in their projects.

Pros of Sanctuary

• More comprehensive documentation and examples
• Stricter type checking and runtime type safety
• Larger ecosystem with additional libraries and extensions

Cons of Sanctuary

• Steeper learning curve due to its more rigorous approach
• Potentially slower performance in some cases due to runtime type checks

Code Comparison

Sanctuary:

S.map(S.add(1), [1, 2, 3])
// => [2, 3, 4]

Folktale:

F.map([1, 2, 3], x => x + 1)
// => [2, 3, 4]

Both libraries provide functional programming utilities, but Sanctuary emphasizes type safety and mathematical correctness, while Folktale focuses on practical, everyday use cases. Sanctuary's approach may lead to more robust code but can be more challenging for beginners. Folktale offers a gentler learning curve and may be more suitable for projects where absolute type safety is less critical.

Sanctuary's stricter typing can catch more errors at runtime, potentially improving code quality. However, this comes at the cost of some performance overhead. Folktale, being more flexible, may offer better performance in certain scenarios but with fewer guarantees about type correctness.

The code comparison shows that both libraries provide similar functionality, but Sanctuary's syntax is more aligned with mathematical notation, while Folktale's is more reminiscent of traditional JavaScript methods.

Pros of Ramda

• More comprehensive library with a wider range of utility functions
• Better performance for large-scale applications
• Stronger focus on functional programming paradigms

Cons of Ramda

• Steeper learning curve for developers new to functional programming
• Less emphasis on algebraic data types and monads
• Larger bundle size, which may impact load times in web applications

Code Comparison

Ramda:

const numbers = [1, 2, 3, 4, 5];
const doubleEvens = R.pipe(
  R.filter(R.both(R.isEven, R.lt(R.__, 10))),
  R.map(R.multiply(2))
);
console.log(doubleEvens(numbers)); // [4, 8]

Folktale:

const { Maybe } = require('folktale/maybe');

const safeDiv = (a, b) =>
  b === 0 ? Maybe.Nothing() : Maybe.Just(a / b);

console.log(safeDiv(10, 2).getOrElse(0)); // 5
console.log(safeDiv(10, 0).getOrElse(0)); // 0

Both libraries offer functional programming tools, but Ramda focuses more on utility functions and data transformation, while Folktale emphasizes algebraic data types and monadic operations. Ramda's approach may be more familiar to JavaScript developers, while Folktale introduces concepts from languages like Haskell.

Pros of Lodash

• Larger ecosystem and community support
• More comprehensive set of utility functions
• Better performance for many operations

Cons of Lodash

• Larger bundle size, which can impact load times
• Less focus on functional programming paradigms
• Some functions may be redundant with modern JavaScript features

Code Comparison

Folktale (Maybe monad):

const { Maybe } = require('folktale');

const result = Maybe.fromNullable(someValue)
  .map(x => x * 2)
  .getOrElse(0);

Lodash (Similar functionality):

const _ = require('lodash');

const result = _.isNil(someValue) ? 0 : someValue * 2;

Folktale emphasizes a more functional approach with monads, while Lodash provides a more imperative style with utility functions. Folktale's code is more expressive for handling nullable values, but Lodash's approach may be more familiar to developers used to imperative programming.

Both libraries have their strengths, with Lodash offering a wider range of utility functions and Folktale focusing on functional programming concepts. The choice between them depends on the project's needs and the team's preferred programming paradigm.

Pros of Fluture

• More focused on asynchronous programming and futures
• Provides a wider range of utility functions for working with futures
• Better performance in handling large numbers of asynchronous operations

Cons of Fluture

• Steeper learning curve due to its more specialized nature
• Less comprehensive documentation compared to Folktale
• Narrower scope, focusing primarily on futures and not other functional programming concepts

Code Comparison

Fluture:

const future = Future((reject, resolve) => {
  setTimeout(() => resolve('Hello'), 1000);
});

future.fork(console.error, console.log);

Folktale:

const task = Task.task(resolver => {
  setTimeout(() => resolver.resolve('Hello'), 1000);
});

task.run().listen({
  onResolved: console.log,
  onRejected: console.error
});

Both libraries provide ways to handle asynchronous operations, but Fluture's API is more focused on futures, while Folktale offers a broader range of functional programming tools. Fluture's approach may be more intuitive for developers working primarily with asynchronous code, while Folktale provides a more comprehensive toolkit for functional programming in JavaScript.