@ultramagn3tic
Lead Developer at Scott Logic by day, Architecturally curious, techno freak by night. Creator of Higher-Kinded-J https://higher-kinded-j.github.io #higher-kinded-j #hkj #java #scala #functionalprogramming Views are frequently my own
What if #Java had Haskell style streaming + production resilience patterns, all composable through higher-kinded types?
Higher-Kinded-J 0.3.6: VStream (lazy pipelines on virtual threads) + Circuit Breaker, Bulkhead, Retry & Saga
github.com/higher-kinded-j/higher-kinded-j/releases/tag/v0.3.6
Its learning to be more like human devs that struggle with these things
#Higher-Kinded-J uses #JavaPoet powered annotation processors eliminating boilerplate in #Java. Annotate a record with @GenerateLenses and get type-safe lenses, prisms, and traversals generated at compile time without runtime cost, just clean source code. higher-kinded-j.github.io/latest/home....
Functional programming in Java shouldn't feel like fighting the language.
In the series finale, we look at "Higher-Kinded-J" in practice:
✅ A 3-layer architecture for pragmatism
✅ Spring Boot integration
✅ Knowing when to use it
It's time for a "Java-native" FP
blog.scottlogic.com/2026/02/12/m...
Functional programming in Java shouldn't feel like fighting the language.
In the series finale, we look at "Higher-Kinded-J" in practice:
✅ A 3-layer architecture for pragmatism
✅ Spring Boot integration
✅ Knowing when to use it
It's time for a "Java-native" FP
blog.scottlogic.com/2026/02/12/m...
Uniting Optics with Effects in a modern fluent Java api. In Part 5 we dive into effect polymorphism and how effects structure our code with Higher-Kinded-J's Effect Path API.
#Java #FunctionalProgramming #Optics #Effects #Programming #OpenSource
blog.scottlogic.com/2026/02/09/e...
Part 4: Traversals & Pattern Rewrites.
Turn verbose tree recursion into declarative, composable paths:
.departments().each().employees().each().salary()
We build a complete expression optimiser using the Focus DSL.
blog.scottlogic.com/2026/01/30/t...
#Java #FunctionalProgramming #Optics #JVM
In Part 3 we build an Abstract Syntax Tree for an Expression Language using latest #Java and #Higher-Kinded-J #FunctionalProgramming #DOP
blog.scottlogic.com/2026/01/23/a...
In Pt2 we dive deeper into the core optics for manipulating nested data in #Java. #FunctionalProgramming blog.scottlogic.com/2026/01/16/o...
Thanks. Part 2 will be out next week
Just published a new article on using #Java for scripting ☕
If you’ve ever wanted to automate something quickly but didn’t feel like fighting with Bash or Python syntax… Java might be a better option than you think.
Shebangs, single-file execution, @jbang.dev and more 👇
👉 tinyurl.com/h3xskenf
This is the first of me new blog series on Functional Optics for Modern Java. We start off with The Immutability Gap: Why Java Records Need Optics blog.scottlogic.com/2026/01/09/j...
#Java #FunctionalProgramming #Optics
Algebra is the power of constraint! What is Algebraic about Algebraic Effects? share.google/a6jZSPgGQpEu...
Higher-Kinded-J 0.3.0 released! New Effect Path API brings railway-oriented programming to Java: Composable error handling that reads just like the business logic it represents. Path.maybe(findUser(id)) .toEitherPath(() -> UserNotFound) .via(this::validateOrder) .map(this::createOrder) ✓ 17+ Composable Path types: EitherPath, TryPath, ValidationPath... ✓ Unified map/via/recover across all effects with .via() and .recover() ✓ Focus DSL bridges effects + optics ✓ Spring Boot 4.0 auto-configuration ✓ Examples and Tutorials One vocabulary. Clean pipelines. Errors that compose. https://higher-kinded-j.github.io/v0.3.0/effect/ch_intro.html
The new Effect Path API in Higher-Kinded-J
A single API to Unify Effects and Optics in Java.
No more nested if-checks, scattered try-catch. Just clean, flat pipelines.
find out more: higher-kinded-j.github.io/v0.3.0/effec...
#Java #Effects #Optics #FunctionalProgramming #Spring #Higher-Kinded-J
This is very interesting and thought provoking series relating software architecture to category theory ibrahimcesar.cloud/blog/categor...
garciat.com/posts/java-t... This is excellent. Really interesting post with lots pearls to digest. I had been thinking a lot about similar things around embedded kind system for checking bounds. #java #hkt #fp
![- 📦 Simple record definitions with @GenerateFocus annotation
- 🔗 Fluent method chaining: .hq().city().set(...)
- 🔄 Immutable updates that return new objects
- 📋 Collection traversal with .each().getAll()
- ✨ Bulk transformations with .modifyAll()
```java
// Define your immutable data
@GenerateFocus
record Company(String name, Address hq) {}
@GenerateFocus
record Address(String city, List<String> phones) {}
Company acme = new Company("Acme", new Address("London", List.of("555-1234", "444-4321")));
// Navigate & modify deep nested data with a fluent DSL
Company updated = CompanyFocus.hq() // Focus on headquarters
.city() // Then the city
.set("Newcastle", acme); // Immutably update
// Traverse collections effortlessly
List<String> allPhones = CompanyFocus.hq()
.phones()
.each() // Focus on each phone
.getAll(acme); // → ["555-1234","444-4321"]
// Transform all elements at once
Company withAreaCode = CompanyFocus.hq()
.phones()
.each()
.modifyAll(p -> "+44-" + p, acme); // → phones: ["+44-555-1234", "+44-444-4321"]
```](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:nbd4h52u5skj76nj6le4a3ms/bafkreiehdvd35fivyd7zw4bi75xfewtviah5dwav5whapzpurh7ywdudbm)
- 📦 Simple record definitions with @GenerateFocus annotation - 🔗 Fluent method chaining: .hq().city().set(...) - 🔄 Immutable updates that return new objects - 📋 Collection traversal with .each().getAll() - ✨ Bulk transformations with .modifyAll() ```java // Define your immutable data @GenerateFocus record Company(String name, Address hq) {} @GenerateFocus record Address(String city, List<String> phones) {} Company acme = new Company("Acme", new Address("London", List.of("555-1234", "444-4321"))); // Navigate & modify deep nested data with a fluent DSL Company updated = CompanyFocus.hq() // Focus on headquarters .city() // Then the city .set("Newcastle", acme); // Immutably update // Traverse collections effortlessly List<String> allPhones = CompanyFocus.hq() .phones() .each() // Focus on each phone .getAll(acme); // → ["555-1234","444-4321"] // Transform all elements at once Company withAreaCode = CompanyFocus.hq() .phones() .each() .modifyAll(p -> "+44-" + p, acme); // → phones: ["+44-555-1234", "+44-444-4321"] ```
The new Focus DSL in Higher-Kinded-J makes working with deeply nested records a breeze.
check it out: higher-kinded-j.github.io/latest/optic...
#Java #FunctionalProgramming
🎯 New: Focus DSL for Higher-Kinded-J!
Type-safe, fluent optics for nested data:
CompanyFocus.headquarters().city()
.modify(String::toUpperCase, company);
Add @GenerateFocus to records. IDE autocomplete included!
🔗 higher-kinded-j.github.io/latest/optic...
#Java #FunctionalProgramming
There is also #SpringSecurity integration and #Actuator integration examples on the website. Really interested to hear feedback from #Spring developers.
Higher-Kinded-J v0.2.3 is out!
Now with Spring Boot starter support - just add dependency:
- Either, Validated, EitherT as controller return types
- Automatic JSON serialisation
- Type-safe error handling REST
higher-kinded-j.github.io/latest/sprin...
#Java
#SpringBoot
#FunctionalProgramming
I would say "Less-Boilerplate" might be more accurate. Some welcome improvements though. amritpandey.io/java-25-the-...
It's amazing how much maths distills to solving a colouring in problem. I knew all that time spent at first school colouring in was important.
www.quantamagazine.org/a-new-bridge...
Practical Free monads in Java
higher-kinded-j shows you how to:
• Build composable DSLs
• Transformations as interpreters
• Stack-safe (10k+ ops verified)
• Test effectful code purely
Complete guide:
higher-kinded-j.github.io/monads/free_...
#Java #FunctionalProgramming #Monads #AdvancedJava
0 o a o © What's New in Higher-Kinded-J 0.2.0 Massive Optics Expansion This release dramatically expands the optics library with 6 new optic types and dozens of utility classes: + Fold, Getter, Setter: New fundamental optic types for read-only queries, single-element access, and write-only modifications + Indexed Optics: Position-aware transformations with IndexedTraversal , IndexedFold ,and IndexedLens + Filtered Traversals: Compose predicates directly into optic chains with filtered() and filterBy() + Limiting Traversals: Focus on specific portions of lists with taking() , dropping() , takingwhile() , slicing() , etc. + PartsOf: Transform all focused elements as a single list with operations like sorted() , reversed() , distinct() + Fluent API: New operator-style API with Free Monad DSL for building composable optic programs with multiple interpreters New Functional Programming Primitives + FreeMonad: Build domain-specific languages (DSLs) with stack-safe execution and multiple interpreters + Trampoline: Stack-safe recursion support for tail-call optimization + Const Functor: Phantom type parameter support for advanced type-level programming + Alternative Type Class: Choice and failure operations for applicative functors Enhanced Type Classes + Monoid: New methods ( firstOptional() , lastOptional() , maximum() , minimum() ) and instances (Long, Double) + Monad: Added flatMap2-5 for sequencing multiple monadic values with effectful combining functions
Six new Composable Optics and a FreeMonad DSL all in the latest #higher-kinded-j release
check it out higher-kinded-j.github.io/optics/optic...
#Java #FunctionalProgramming #Monads #Optics
🎉 New in higher-kinded-j: Bifunctor support!
Transform both sides of your data structures with bimap, first, and second operations.
✨ Use with Either, Tuple2, Validated, and Writer
✨ Type-safe
✨ Law-verified
higher-kinded-j.github.io/functional/b...
#Java #FunctionalProgramming #TypeSafety
🚀 New Selective support in latest #higher-kinded-j release🚀
Bringing the power of conditional effects to #Java use Selective with
* Either<E, *>
* Maybe
* Optional
* List
* IO
* Reader<R, *>
* Id
* Validated<E, *>
Find out more: higher-kinded-j.github.io/functional/s...
Nice post. Lots of interesting applications of this with profunctor adapter patterns.
🚀 New Higher-Kinded-J 0.1.8 🚀
✨ Protofunctors - Transform both inputs & outputs of your functions with dimap, lmap, rmap
🔍 Protofunctor enhanced Optics - Lens, Prism, Traversal & Iso for immutable data manipulation
Checkout the hkj-book higher-kinded-j.github.io/functional/p...
#Java #FP #Optics
Original post: mastodon.scot/@Wen/1151514...
