Monix is a high-performance Scala/Scala.js library for asynchronous, effectful, and reactive programming, consumed as a dependency rather than run as an application. It provides four core data types: Task (an asynchronous, cancelable effect with a trampolined run loop), Coeval (synchronous lazy evaluation), Observable (a push-based, back-pressure-respecting stream with a very large operator suite), and Iterant (a pull-based functional stream with primitive-specialized batch cursors). Alongside these it ships monix-execution (Scheduler hierarchies with trampolining/batching, a rich Cancelable family, cache-line-padded lock-free atomics, concurrent queues) and monix-catnap (MVar, Semaphore, CircuitBreaker, ConcurrentChannel, ConcurrentQueue, FutureLift). There is no standalone entry point; integration is via sbt libraryDependencies, and the build is a multi-module sbt project cross-compiled for JVM and Scala.js with shared sources plus platform-specific jvm/js implementations.
Scalaz is a mature, purely functional programming library for Scala, providing a comprehensive set of type classes (Functor, Monad, Traverse, Foldable, etc.), monad transformers (OptionT, StateT, WriterT, etc.), effect types (IO, ST, RegionT), efficient immutable data structures (IList, Tree, FingerTree, Heap, Dequeue, etc.), and syntactic enrichment for all of the above. It is organized into modular sub-projects (core, effect, iteratee, scalacheck-binding) and supports cross-compilation to JVM, JavaScript, and Native platforms across Scala 2.13 and 3. The library is designed for production use and serves as both a practical toolkit and a reference implementation of category theory concepts in Scala. While primarily a library, it contains advanced research-level abstractions (free monads, cofree comonads, finger trees) that make it a valuable resource for functional programming education.
recheck is a monorepo for a ReDoS (Regular expression Denial of Service) vulnerability checker, written in Scala 3 and cross-compiled to JVM and JavaScript via Scala.js. The system parses regular expression patterns, builds an execution model, and detects catastrophic backtracking vulnerabilities. It exposes multiple interfaces: a core library (`recheck-core`) with a high-level `ReDoS.check` API, a CLI (`recheck-cli`) with `check` and `batch` subcommands (the latter using JSON-RPC over stdio), JavaScript bindings (`recheck-js`) for browser/Node usage, and an ESLint plugin (`eslint-plugin-redos`) for CI integration. The architecture is a multi-module sbt build with Lerna/pnpm for JS workspace management, featuring clean separation between parsing, execution, unicode data, and platform-specific adapters.