Chameleon
Haskell-type language, implements ideas described in a 'A Theory of Overloading'. Compiles Chameleon to (plain) Haskell; can mix Haskell and Chameleon overloading. Descriptions, documents, downloads.
Data Field Haskell
Dialect with instance of data fields (a generalization of arrays), useful for rapid prototyping of parallel algorithms, and parallel high-level system specification.
Distributed Haskell
Extension for parallel and distributed programming, with combinators from concurrent constraint programming; computational parts of programs are expressed functionally, development was first for tightly coupled multiprocessors, evolved from Goffin.
Eden
Extends lazy functional language Haskell, but overrules lazy evaluation whenever needed to support parallelism; gives programmers enough control to implement parallel algorithms efficiently, and frees them from low level details of process management.
Glasgow Parallel Haskell (GpH)
A Haskell extension for parallel programming built on top of the Glasgow Haskell compiler (GHC). Parallelism is identified using annotations (generally evaluation strategies), that are defined using only two extra primitives: par and seq.
Gofer
Small interpreter for language based on Haskell report 1.2; experimental, more so for type classes. Haskell adopted some ideas of Gofer, but Gofer type class system is more flexible. Runs on DOS, Linux, Macintosh, Unix. Hugs predecessor.
Haskell++
Object-oriented Haskell extension, using a preprocessor, supports a form of inheritance via extended class and instance declarations. Descriptions, documents, source download, links.
Helium
A functional programming language (subset of the Haskell) and a compiler designed especially for teaching Haskell.
Hugs
An interpreter for Haskell which runs on almost any platform. Primarily used for teaching.
Hugs Archive
Many files for Hugs Haskell interpreter: source code, documents.
Jaskell Project
Java bytecode generator backend for Glasgow Haskell Compiler (GHC), so one can build Java applets or applications via the Haskell language.
Mondrian
Light version of Haskell to interoperate with other languages in OO environments; runs on .NET (old version for JVM), supports ASP.NET, to embed functional code in webpages with C#. Has version of Glasgow Haskell Compiler using Mondrian for .NET system to compile Haskell for .NET.
O'Haskell
Object Haskell: Haskell conservatively extended with subtyping, monadic objects.
pH (MIT parallel Haskell)
A parallel eagerly evaluated variant of Haskell with syntactic provisions for loops, barriers, and I- and M- structure storage.
PolyP
Polytypic programming language; source files for compiler written in Haskell that compiles PolyP-code to Haskell; library of polytypic functions written in PolyP, some examples, documents, downloads.
Template Haskell
Haskell 98 extension allowing type-safe compile time metaprogramming, with Haskell, as the manipulating language and the language being manipulated.
The Glasgow Haskell Compiler (GHC)
An optimizing compiler for Haskell, written in Haskell. Includes extensions for concurrency and heap & time profiling. [Open Source, BSD-like]
The HBC compiler
A compiler and interactive system for Haskell 1.4, unsupported for two years now.