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Gradual Typed Functional Programming with Javascript

scriptum consists of two parts

• a typed standard functional library based upon a higher-rank/kinded runtime type validator
• and an untyped standard functional library

The untyped library serves as a playground to explore Haskell idioms and translate them to Javascript. In a second step these translations are type annotated and incorporated into the typed library. Please note that scriptum supports a wide range of Haskell idioms, because it ships with

• lazy evaluation with implicit thunks (and thus guarded recursion)
• tail recursion through trampolines
• persistent data structures based on R/B trees
• safe mutations without sharing
• Scott encoded sum types (augmented with record syntax)
• type classes through dictionary passing (with lots of pre-defined dictionaries)
• effect system based on monad transformers
• pure concurrency through async operations (parallel/serial)
• loop fusion with transducers
• functorial fusion with yoneda/coyoneda
• flat syntax through special applicator type and infix operators

Status

Unstable (v0.9.2)

Goals

In order to create an ecosystem for the functional paradigm in Javascript the following main aspects need to be supplied:

• [x] type safety
• [x] algebraic data types
• [x] value level type classes
• [x] lazy evaluation with thunks
• [x] persistent data structures
• [x] safe in-place updates
• [x] stack-safe sync/async recursion
• [x] effect handling and composition
• [ ] probabilistic data structures
• [ ] software transaction memory (STM)
• [ ] distributed programs based on STMs
• [ ] separation of command and query model + event sourcing (CQRS/ES)
• [ ] strong eventual consistency (CRDTs)