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I have to say it: I like ReScript. Its features and tooling provide a great developer experience. I wish it was my main tool at work, however…it isn't, since most of the commercial projects I have worked on recently have been built with TypeScript. This is fully understandable from a business perspective because it is easier to find developers who are familiar with TypeScript ¯\_(ツ)_/¯.

I like the functional programming (FP) paradigm, and I follow FP principles in almost every project I work on. Therefore, in the past few years I have been able to test and use some JavaScript/TypeScript libraries that follow these principles.


Below are my opinions and thoughts on FP libraries that I have previously used on a daily basis at work, and I fully understand if you disagree with them.

Ramda ⬇️

Pros: Ramda is a mature project, it contains tons of utility functions, and has great, detailed documentation.

Cons: Using the pipe function feels unnatural (for example: pipe(fn1, fn2)(value)), TypeScript support is neglected (the type inference simply doesn’t work well), and the data-last approach makes code less readable.

Comment: Since Ramda doesn't play well with TypeScript, I only found it useful in JavaScript-based projects.

Rambda ⬇️

Pros: Rambda is super fast, and I really mean it: it’s difficult (but not impossible) to beat rambda in terms of overall performance!

Cons: Similar problems to ramda.

Remeda ⬇️

Pros: Remeda provides a data-first approach, which is more natural and developer friendly. remeda has good documentation, and its TypeScript support is great.

Cons: According to my benchmark results, remeda is the slowest compared to the other libraries. Its use of lazy evaluation also makes it unclear how to use some utility functions within a pipeline.

Comment: It's been my first choice for a long time.

TS Belt ⬇️

Until…I decided to build ts-belt. ts-belt combines all of the good things you can find in other similar libraries: the developer friendly data-first approach, good documentation, great TypeScript support, and last but not least, it's as fast as rambda (actually, it's even faster 🙊). Under the hood it uses ReScript and the Belt standard library. The ReScript compiler generates highly performant JavaScript code, and with genType it automatically generates TypeScript signatures. ts-belt is also easily extendable because most of the build process is done automatically.


  • 🚀 built with ReScript, which generates highly performant JavaScript code (see benchmark results)
  • 👀 provides more readable code, due to the data-first approach
  • ✨ supports TypeScript and Flow
  • 🛡 helps you write safer code with Option and Result types
  • 🎯 all functions return immutable data (no side-effects)
  • 🌲 tree-shakeable
  • 📝 fully documented