Nickel is an experimental programming language intended to be used as a compile target for high-performance functional languages. Its main features are:

• Complete type and memory safety verified at compile-time. Nickel programs cannot trigger undefined behavior except by linking against unsafe external libraries.
• Robust functional purity guarantees. Nickel functions are deterministic and capture all output via return values.
• Predictable performance and precise control over memory management. Nickel can support languages without a garbage collector or even a heap allocator.
• Efficient in-place mutation of data structures, while ensuring functional purity via linear types.
• An expressive type system which includes first-class support for arbitrary-rank universal quantification, existential quantification, and generalized algebraic data types.

Nickel is currently in an extremely early stage of development. At the moment, it consists mainly of a preliminary design and a prototype compiler under construction. Eventually, the Nickel toolchain will include:

• A Nickel compiler targeting LLVM and WebAssembly
• A standalone Nickel type checker
• Utilities for converting between multiple equivalent representations of Nickel programs, including:
  • A human readable, human writable plain text format resembling a high level functional programming language
  • A JSON representation which can be easily generated or parsed from any language.
  • A compact binary format suitable for storing and distributing Nickel code.
• An optional standard library providing type and memory safe wrappers around platform functionality like memory management and IO.
• A graphical debugger for exploring the runtime behavior of Nickel programs. Because Nickel is purely functional, this debugger can easily step backwards as well as forwards.

Questions and contributions are welcome! Please contact William Brandon to learn more.