fantasy-land VS cats

Compare fantasy-land vs cats and see what are their differences.

fantasy-land

Specification for interoperability of common algebraic structures in JavaScript (by fantasyland)

cats

Lightweight, modular, and extensible library for functional programming. (by typelevel)
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fantasy-land cats
21 43
9,997 5,177
0.2% 0.5%
3.1 8.8
4 months ago 6 days ago
JavaScript Scala
MIT License GNU General Public License v3.0 or later
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.

fantasy-land

Posts with mentions or reviews of fantasy-land. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-08-16.
  • Functional Programming 1
    3 projects | news.ycombinator.com | 16 Aug 2023
    2. https://github.com/fantasyland/fantasy-land (A bit heavy on jargon)

    Note there is a python version of Ramda available on pypi and there’s a lot of FP tidbits inside JAX:

    3. https://pypi.org/project/ramda/ (Worth making your own version if you want to learn, though)

    4. For nested data, JAX tree_util is epic: https://jax.readthedocs.io/en/latest/jax.tree_util.html and also their curry implementation is funny: https://github.com/google/jax/blob/4ac2bdc2b1d71ec0010412a32...

    Anyway don’t put FP on a pedestal, main thing is to focus on the core principles of avoiding external mutation and making helper functions. Doesn’t always work because some languages like Rust don’t have legit support for currying (afaik in 2023 August), but in those cases you can hack it with builder methods to an extent.

    Finally, if you want to understand the middle of the midwit meme, check out this wiki article and connect the free monoid to the Kleene star (0 or more copies of your pattern) and Kleene plus (1 or more copies of your pattern). Those are also in regex so it can help you remember the regex symbols. https://en.wikipedia.org/wiki/Free_monoid?wprov=sfti1

    The simplest example might be {0}^* in which case

    0: “” // because we use *

  • Ramda: A practical functional library for JavaScript programmers
    7 projects | news.ycombinator.com | 4 Aug 2023
    It was never really my jam, but I used to follow the up-and-coming fantasy-land specs with great interest. It just seemed like a sharp dedicated community of folks trying to figure out better fp & algebraic stuff. I'm not sure who trailed off - in general I feel like there's much less connection in tech world, that the tech twitter and every other ultra-active tech channel has somewhat decayed. https://github.com/fantasyland/fantasy-land

    Thanks for the links. I know I've seen @gcanti's name a thousand times already, but it's already quite murky to me what it was attached to. Something in this sphere.

  • How elaborate could/should a transducers combiner function be?
    2 projects | /r/functionalprogramming | 5 Jan 2023
    Look at the implementations of Fantasy Land. List-in-JS might do the trick.
  • General Functional Programming Resources
    3 projects | /r/functionalprogramming | 17 Dec 2022
  • Should I Move From PHP to Node/Express?
    13 projects | /r/node | 13 Oct 2022
    There are respective fantasy land and static land specs, with the law conformance checks.
  • I came across the "Fantasy Land Specification", it somewhat conflicts with my own simplistic understanding of monads and functors. Is this specification valid, and should I honor it?
    2 projects | /r/functionalprogramming | 11 Sep 2022
    While building a purely functional data structure library for personal fun and professional use, and while using other libraries, I found that the "Fantasy Land Specification" was mentioned from time to time. They use this hierarchy. Although I did read some about category theory (tried and failed to fully understand all the concepts), some of the terms used in the specification are unknown to me (like Chain, Apply). My question:
  • Best explanation of monads ive ever seen, from the practical developper’s point of view.
    3 projects | /r/programming | 8 Jul 2022
    No: neither of those examples are "properties of futures and of lists as such." "Async/Await" in particular is a special case of monadic behavior of a concurrency monad. This specifically (infamously) came up in the evolution of the Prommise spec in ECMAScript, which in turn led to the development of the Fantasy Land Spec and various implementations of it.
  • should i learn design patterns?
    1 project | /r/node | 7 Jul 2022
  • Design Patterns Book for functional programming?
    1 project | /r/functionalprogramming | 5 Jun 2022
    If you're programming in TypeScript you can checkout the fantasy land spec. It provides a spec for all the algebraic structures used in the JS world. You can learn what they are. You'll want to find alternative resources to learn what they are how they work. Fantasy land is just a spec not a guide.
  • Ruby in FantasyLand: SumsUp
    3 projects | dev.to | 23 May 2022
    Javascript comes with this lovely little spec called Fantasy Land that defines certain type classes in Category Theory and how they interact.

cats

Posts with mentions or reviews of cats. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-07-05.
  • Beware of teammates who refactor code based on personal taste without proper documentation or completeness. Sounds familiar.
    2 projects | /r/programming | 5 Jul 2023
    A functional programming library: https://typelevel.org/cats/
  • Is Scala worth learning in 2023?
    5 projects | /r/scala | 29 Jun 2023
    Learn something that pays the bill first - nowadays it's Golang/Rust react/typescript. Then you can try some pure fp libs like fp-ts and fp-core.rs, and look through existing scala cats docs. If you'll feel bad about it - that's totally fine and expectable, fp takes a paradigm shift and not that many dev able to shift their brains way of thought due to basic psychological rigidity) (inability to change habits and to modify concepts/attitudes once developed). And that's purely a staffing and management issue - folks hired randoms out of the blue, and called 'em a team.
  • Going into year 2 of Software Development Foundation Degree, have a particular liking for OOP and SQL, any tips, info or pointers on where to go from there?
    2 projects | /r/cscareerquestions | 29 May 2023
    I'm sorry, but have you ever done functional programming for a real company, like in a functional programming language like Haskell, Scala, or F#? Have you ever used Scala cats or scalaz? Have you ever learned category theory and how to apply its abstractions in software? Listen u/judethedude2106 this person hasn't gone as far down the functional programming rabbit hole as I have. Beyond learning the basics like the difference between pure and impure functions, what are closures, what higher order functions are and the most common ones like .map, .filter, and .flatmap, the immutable collections like immutable linked lists and trees, and what a Monad is and common monads like those used for futures/promises, async programming, and Option (Some or None, which is used instead of null checking), the more advanced functional programming stuff like category theory based abstractions are totally useless for real jobs and is just a giant time suck. Don't waste years on functional programming, spend at most a few months on it and no more.
  • rsmonad: Monads in stable Rust (+ Applicative, Alternative, Functor, Monoid, ...)
    2 projects | /r/rust | 24 May 2023
    As a former functional programmer in Scala, please do not go deep into the Category Theory programming. Scala has libraries like this one called "Cats", a cute shortened name for "Category Theory", but code that makes heavy use of these constructs is not understandable to other programmers. Other than using Monads as a design pattern for things like Options (which can be "Some" or "None"), Futures or Promises (which is used for asynchronous programming), and a few other things, please do not make heavy use of category theory constructs in real programming projects that will have other developers working on them. It is a rabbit hole that may be fun but is not super practical. Sure, write pure functions without side effects, but do not use the words "Bimonad", "Invariant Monoidal", and "Semigroup" in your code. The most common, practical application/use of functional programming is basic things like closures, .map, .filter, maybe chaining maps with like a .flatmap or whatever your programming language uses instead of chain or flatmap, and SQL that uses keywords like WHERE which can be represented in code by using a call to .filter. Like the place where these constructs are used most is in data processing like with SQL, ETL (Extract Transform, Load) jobs, Java's MapReduce on Hadoop, Scala's Apache Spark, and other data processing type things. Haskell is not a popular programming language in real world projects for a number of reasons and one of them is the heavy and sometimes impractical use of Category Theory.
  • Tmux, NeoVim, etc. to write pure Kotlin code?
    2 projects | /r/Kotlin | 30 Apr 2023
    At a previous job of mine we actually had an entirely pure Scala ecosystem using cats which instead uses typeclasses, referential transparency, and other FP concepts as the foundations for how to code. So a lot of flexibility to the language.
  • [E => *] Type
    2 projects | /r/scala | 9 Mar 2023
    Thanks! It's used heavily here
  • for comprehension and some questions
    3 projects | /r/scala | 22 Jan 2023
  • Ask HN: How has functional programming influenced your thinking?
    4 projects | news.ycombinator.com | 16 Jan 2023
    I did work in Scala for a few years. We employed Cats[1], and even a bit of Matryoshka[2] though most of the work I do today is in Python.

    Nowadays I think about computational requirements in terms of relations among behavioral dependencies. Like, "I want to perform operation O on input A and return a B. To do this, I'll need a way to a -> b and a way to b -> b -> b." I often pass these behavioral dependencies in as arguments and it tends to make the inner core of my programs pretty abstract and built up as layers of specificity.

    Zooming out nearly all the way, it makes me feel tethered in a qualitatively unique way to certain deep truths of the universe. In a Platonic sense, invoking certain ideas like a monad make me feel like I'm approaching the divine or at least one instantiation of a timeless universal that operates outside of material existence.

    I'd imagine some mathematicians might see the universe in a similar way - one where immortal relations between ontological forms exist beyond time and space and at the same time can be threaded through the material world by intellectual observation and when those two meet a beautiful collision occurs.

    1. https://typelevel.org/cats/

    2. https://github.com/precog/matryoshka

  • yet another post about type classes in Scala
    2 projects | dev.to | 2 Jan 2023
    Our second type class example attempted to illustrate one last perk: type safety at compile time. It did so with a simplified example of the cats core library for type safety equality comparison between objects. If you're not familiar with cats, go ahead and give it go.
  • What are the design principles of Cargo?
    1 project | /r/rust | 1 Dec 2022

What are some alternatives?

When comparing fantasy-land and cats you can also consider the following projects:

worldle

Scalaz - Principled Functional Programming in Scala

awesome-functional-programming - Yet another resource for collecting articles, videos etc. regarding functional programming

Shapeless - Generic programming for Scala

awesome-functional-python - A curated list of awesome things related to functional programming in Python.

ZIO - ZIO — A type-safe, composable library for async and concurrent programming in Scala

ramda - :ram: Practical functional Javascript

ScalaTest - A testing tool for Scala and Java developers

newtype-ts - Implementation of newtypes in TypeScript

Monocle - Optics library for Scala

Exercism - website - The codebase for Exercism's website.

Scala Async - An asynchronous programming facility for Scala