Open Source Haskell Compilers

Koka is a strongly typed functional-style language with effect types and handlers. The core of Koka consists of a small set of well-studied language features, like first-class functions, a polymorphic type- and effect system, algebraic data types, and effect handlers. Each of these is composable and avoid the addition of “special” extensions by being as general as possible. Koka tracks the (side) effects of every function in its type, where pure and effectful computations are distinguished. The precise effect typing gives Koka rock-solid semantics backed by well-studied category theory, which makes Koka particularly easy to reason about for both humans and compilers. Effect handlers let you define advanced control abstractions, like exceptions, async/await, or probabilistic programs, as a user library in a typed and composable way. Perceus is an advanced compilation method for reference counting.

Clash is a functional hardware description language that borrows both its syntax and semantics from the functional programming language Haskell. It provides a familiar structural design approach to both combinational and synchronous sequential circuits. The Clash compiler transforms these high-level descriptions to low-level synthesizable VHDL, Verilog, or SystemVerilog. Clash is an open-source project, licensed under the permissive BSD2 license, and actively maintained by QBayLogic. The Clash project is a Haskell Foundation affiliated project. Clash is built on Haskell which provides an excellent foundation for well-typed code. Together with Clash's standard library it is easy to build scalable and reusable hardware designs. Load your designs in an interpreter and easily test all your component without needing to setup a test bench. Although Clash offers many features, you sometimes need to directly access VHDL, Verilog, or SystemVerilog directly.

BSC is the open source compiler toolchain for Bluespec SystemVerilog, a high-level, rule-based hardware design language. It translates Bluespec descriptions into synthesizable Verilog, letting developers bring typed, modular abstractions into mainstream FPGA/ASIC flows. The compiler performs scheduling of atomic rules, elaborates parameterized modules, and enforces interface contracts, producing predictable RTL that integrates with existing EDA tools. A companion simulator enables fast functional execution and debugging before handing designs to traditional verification and synthesis stages. The ecosystem includes standard libraries, FIFOs, interfaces, and utilities that encourage reuse and clean separation of datapaths and control. By raising the abstraction for hardware architecture while preserving efficient output, BSC helps teams explore complex designs—such as RISC-V cores or accelerators—more productively.

Elm uses type inference to detect corner cases and give friendly hints. NoRedInk switched to Elm about four years ago, and 300k+ lines later, they still have not had to scramble to fix a confusing runtime exception in production. The compiler guides you safely through your changes, ensuring confidence even through the most wide-reaching refactorings in unfamiliar codebases. Including your own, six months later. All Elm programs are written in the same pattern, eliminating doubt and lengthy discussions when deciding how to build new projects and making it easy to navigate old or foreign codebases. Enjoy Elm's famously helpful error messages. Even on codebases with hundreds of thousands of lines of code, the compilation is done in a blink. Elm has its own virtual DOM implementation, designed for simplicity and speed. All values are immutable in Elm, and the benchmarks show that this helps us generate particularly fast JavaScript code.

GHC (Glasgow Haskell Compiler) is the leading open-source compiler and interactive environment for the Haskell programming language, supporting the Haskell 2010 standard plus numerous language extensions. It compiles to native machine code (via LLVM or C), and includes the interactive GHCi REPL. For full information on building GHC, see the GHC Building Guide. Here follows a summary - if you get into trouble, the Building Guide has all the answers. For building library documentation, you'll need Haddock. To build the compiler documentation, you need Sphinx and Xelatex (only for PDF output).

A compiler to generate JavaScript code from Haskell. It even has a website and a mailing list. Seamless, type-safe single program framework for client-server communication. Support for modern web technologies such as WebSockets, WebStorage and Canvas. Simple JavaScript interoperability. Generates small, fast programs. Supports all GHC extensions except Template Haskell. Uses standard Haskell libraries. Cabal integration, simple, one-step build; no need for error prone Rube Goldberg machines of Vagrant, VirtualBox, GHC sources and other black magic. Concurrency and MVars with Haste.Concurrent. Unboxed arrays, ByteArrays, StableNames and other low level features. Low-level DOM base library. You have three options for getting Haste: installing from Hackage, from Github or from one of the pre-built binary packages.

Futhark is a small programming language designed to be compiled into efficient parallel code. It is a statically typed, data-parallel, and purely functional array language in the ML family, and comes with a heavily optimizing ahead-of-time compiler that presently generates either GPU code via CUDA and OpenCL, or multi-threaded CPU code. Futhark is not designed for graphics programming, but can instead use the compute power of the GPU to accelerate data-parallel array computations. The language supports regular nested data-parallelism, as well as a form of imperative-style in-place modification of arrays, while still preserving the purity of the language via the use of a uniqueness type system. While the Futhark language and compiler is an ongoing research project, it is quite usable for real programming and can compile nontrivial programs which then run on real machines at high speed.

Fay is a compiler for a proper subset of Haskell that type-checks using GHC and compiles to JavaScript. It supports pure functional programming, a Fay-specific monad, FFI, optional tail-call optimization, and integration with Cabal packages. GHC-compatible type checking, ensuring correctness. Lazy, pure functional semantics with a distinct Fay monad. Foreign Function Interface (FFI) to integrate native JS code. Compatible with standard Haskell packaging tools like Cabal.

Experimental compiler for an extended version of the Curry programming language

More Than Parsing is a parser generator for context free grammars defined in a BNF-like format. It generates scanners, parsers, ASTs, etc. This sf project is no longer active, development will continue in a different place.

A compiler which translated AspectFun program into Haskell.

Asterius is a Haskell toolchain that compiles to WebAssembly, enabling Haskell programs to run in the browser and other Wasm hosts. It builds on GHC, lowers Haskell code to WebAssembly modules, and links them with a lightweight JavaScript runtime for I/O, GC interaction, and host integration. The toolchain provides commands to build and link (ahc/ahc-link), bundle assets, and target both browser and Node environments. Interop is a core focus: Haskell functions can call into JavaScript and vice versa, making it feasible to combine Haskell logic with web APIs. Asterius aims to keep as much of Haskell’s runtime model as practical while delivering the portability and startup characteristics of Wasm. By bridging GHC and WebAssembly, it opens a path to reuse Haskell libraries on the client side without switching languages.

Here we have fun developing software related to embedded extension languages and small languages in many application domains, using existing languages and/or creating new ones.

Fusion is a powerful high level programming language that merges several feature from Ruby, Python, Java, C++, Visual Basic, etc, in a only language. It's implemented by means of a compiler written in Haskell that generates Ruby code.

GHCJS is a Haskell-to-JavaScript compiler that reuses GHC’s front end to compile Haskell source into JavaScript for execution in browsers and Node.js. It aims to preserve Haskell’s semantics—including laziness and rich types—by shipping a small runtime and shims for core libraries. Developers write normal Haskell, use Cabal/Stack to build, then bundle the generated JavaScript alongside required support code. Interoperability with the JavaScript world is provided through a foreign-function interface, allowing Haskell code to call browser APIs or Node modules and to be called back from JS. The ecosystem includes packages tailored to GHCJS (for example DOM bindings and FRP libraries), enabling full single-page apps written in Haskell. Because it mirrors GHC closely, many pure Haskell libraries “just work,” making it practical to share code between server and client.

We extend the Eclipse IDE with tools for development in Haskell, a functional programming language, providing support for a wide range of tools (compilers, interpreters, doc tools etc.) in a coherent, convenient and configurable environment.

Language Prototyping System

The Glasgow Haskell Compiler is a robust, fully-featured, optimising compiler for the Haskell 98 programming language. Please note, we are no longer using the SourceForge bug tracker. Please go to http://cvs.haskell.org/trac/ghc instead.

A front end for haskell with support to multiparameter type classes.

Kaya: A statically typed, imperative cross-platform programming language with type inference, powerful data description capabilities and built-in abstractions and libraries for easy and robust web application development. http://kayalang.org/

Programming language based off pure type systems, and COQ. Currently aimed at both systems, and application programming. Has a simple syntax, and (planned) C integration.

MUgen is an emulator generator which works in a way similar to yacc. It takes an input machine description and outputs a source file which is a fully implemented emulator of that system. This is the open-source system.