clojure-news-feed VS malli

Your question is interesting to me. As a software architect, I study various tech stacks and programming languages. I concentrate mostly on open source and microservice architectures. I usually start with implementing the same feature identical rudimentary news feed microservice. Over time you start to see the similarities and differences between the various implementations. I blog about this over at https://glennengstrand.info and the source code can be found in https://github.com/gengstrand/clojure-news-feed

You are looking for a decision on what programming language and tech stack to learn next based on career mobility. Here are some questions to consider.

What kind of company are you most interested in working for? Think about the size of the company. Is it in a growth market or is profitability more important? Is it a technology company? Does the CEO view technology as a profit center or a cost center? Do they have a CTO? If they do, then who does the CTO report to, the CEO, the CIO, or the COO?

What kinds of programming languages and tech stacks are on the career pages for the kinds of companies that you are most interested in? Different kinds of companies tend to cluster around different tech stacks. There are other factors to filter for such as how deeply do they embrace remote work or commute distance to where you currently live or are willing to move to.

These are lagging indicators. They are going to be more accurate than leading indicators but that also might indicate that whatever you learn next based on these factors might have a shorter shelf life.

Finally, you should ask yourself what about your current programming language do you like? Try to pick something that you would also like. The Go programming language was originally invented as a better C and is enjoying some marketability right now. Maybe that would be something to look at.

I have a github repo where I implement a feature identical microservice in various tech stacks. I started that repo with a Clojure version that used community provided wrappers. See https://github.com/gengstrand/clojure-news-feed/blob/master/... as an example of calling Cassandra. Recently, I added another implementation with Clojure that just called the Java drivers directly. See https://github.com/gengstrand/clojure-news-feed/blob/master/... for that version of the same call. In the end, I decided to forego wrappers and make the calls directly because you end up with fewer dependencies and are more likely to be able to use latest versions of everything.

I have been exposed to many different tech stacks over the years. This https://github.com/gengstrand/clojure-news-feed repo contains the code used to evaluate thirteen different stacks which is what I can share publicly. What I can say is that the best choice of tech stack depends on what is being called for. Is this for an early stage startup or an intrepreneurial greenfield project? Is this for an MVP or just the next component in an already formalized microservice architecture? What are the skillsets of the developers that you will have access to? Have you reached agreement that you can throw it all away and start over or are you expected to have to live with the choice of tech stack for the life of the product? Are you mobile first? These are all important questions that very much shape the decision.

Clojure's lazy sequences by default are wonderful ergonomically, but it provides many ways to use strict evaluation if you want to. They aren't really a hassle either. I've been doing Clojure for the last few years and have a few grievances, but overall it's the most coherent, well thought out language I've used and I can't recommend it enough.

There is the issue of startup time with the JVM, but you can also do AOT compilation now so that really isn't a problem. Here are some other cool projects to look at if you're interested:

Malli: https://github.com/metosin/malli

Babashka: https://github.com/babashka/babashka

Clerk: https://github.com/nextjournal/clerk

BREAKING: walking a :schema passes children instead of [id] to the walker function #884

When you get to larger, more complex validations, I'd recommend checking out Malli or Spec.

for specs, you can try malli - feels pretty well supported and full featured: https://github.com/metosin/malli (i'm not 100% sure how popular it is for others, but I use it on my personal projects)

Have you tried malli: Data-driven Schemas for Clojure/Script?

All that being said, I particularly use malli and I don't find anything to complain about. There is a very nice and sound ecosystem being built around it (malli-ts is one of my contributions to it, but still in early development stages). I highly recommend reading its README, very informative stuff.

Any large codebase can be broken up into small isolated components that can be reasoned about independently. This is how you structure Clojure projects if you want them to be maintainable. Clojure inherently encourages doing this by defaulting to immutability. The contract between components is the data being passed to the component and returned by it. Using Malli schemas at the edges of the components is a typical approach to documenting their APIs https://github.com/metosin/malli

I see the fact that people often end up creating large and tightly coupled monolithic codebases in static languages as a negative aspect of static typing. Such codebases are difficult to reason about even if you have guarantees that the types align. Ultimately, you need to understand the relationships in code, and how they relate to business logic. The more coupling an application has the harder it becomes to reason about it as a whole.

Ideally, I think applications should be structured as a bunch of Lego blocks that can be composed together. Each component should encapsulate some functionality, and then the flow of the business logic should bubble up to the top and expressed in how these components are chained together.

Uhhh spec has existed for a long time and before that, schema Nowadays we also have the excellent malli. If his codebase is full of functions where the shape of the data isn’t obvious, isn’t documented and isn’t specified in a specific/schema, that’s on him and his bad coding practices and really no different from passing data in other dynamic languages. A class by itself (without additional effort) only gives you field names.