​​Flix: Next-generation reliable, safe, concise, and functional-first programming language.

Flix is inspired by OCaml and Haskell with ideas from Rust and Scala. Flix looks like Scala, but its type system is based on Hindley-Milner. Two unique features of Flix are its polymorphic effect system and its support for first-class Datalog constraints.

Flix aims to offer a unique combination of features that no other programming language offers, including: algebraic data types and pattern matching (like Haskell, OCaml), extensible records (like Elm), type classes (like #haskell, #rust), higher-kinded types (like Haskell), local type inference (like Haskell, OCaml), channel and process-based concurrency (like #go), a polymorphic effect system (unique feature), first-class Datalog constraints (unique feature), and compilation to JVM bytecode (like #scala).

https://flix.dev/

Personal opinion: it has all the features new modern programming language should have. It has nice syntax, powerful ideas, and (hopefully) good JVM integration and code-reuse. That's a recipe for a success. I will keep an eye on this amazing language.

It also has a playground on its website, check it out!
I would love to highlight this example of polymorphic effects: