Now that the Haskell report has appeared in SIGPLAN Notices, it seems like a good time to broadcast the current status of Haskell implementations. Below appears an up-to-date summary of implementations known to me. If there are other implementations about, please let me know! Simon Peyton Jones Haskell: Current status ~~~~~~~~~~~~~~~~~~~~~~~~ Simon Peyton Jones, Phil Wadler, Will Partain, Cordy Hall, Kevin Hammond Dept of Computing Science, Glasgow University, Glasgow G12 8QQ, Scotland. email: [EMAIL PROTECTED] (April 1991; additions, November 1991, June 1992) The Haskell language ~~~~~~~~~~~~~~~~~~~~ In September 1987 a meeting was held at the conference on Functional Programming Languages and Computer Architecture in Portland, Oregon, to discuss an unfortunate situation in the functional programming community: there had come into being more than a dozen non-strict, purely functional programming languages, all similar in expressive power and semantic underpinnings. There was a strong consensus at the meeting that more widespread use of this class of functional languages was being hampered by the lack of a common language. It was decided that a committee should be formed to design such a language, providing faster communication of new ideas, a stable foundation for real applications development, and a vehicle through which others would be encouraged to use functional languages. The Haskell committee released its report on 1 April 1990. A revised version (Version 1.2) appeared in SIGPLAN Notices 27(5) (May 1992), along with a tutorial on Haskell by Hudak and Fasel. Implementations of Haskell ~~~~~~~~~~~~~~~~~~~~~~~~~~ This is a frank summary of the implementations of Haskell known to us. hbc Chalmers A serious and mature compiler. Use this hbi if you want to write large Haskell programs. hbi is an interactive version. Written in LML. You need a big machine. glhc Glasgow Another serious compiler, but less mature than hbc. Intended partly as a framework for implementors. Written in Haskell, generates C. You need a big machine. yh2.0 Yale A compiler from Haskell to Lisp, built on top of Common Lisp (EuLisp and Scheme should also work). An interactive, integrated Haskell programming environment. Supports both large scale Haskell programming and educational use. Needs a moderately big machine - we expect to release a Mac and PC version soon. Supports language implementors. Expected release: August 1992. gofer Oxford An interpreter for a language very similar to Haskell. A "best buy" if you just want to get started. Much much faster to use than the compilers below for small programs, because it compiles and loads programs amazingly fast. Written in C, and portable; you don't need a big machine! Only implementation to work on IBM PCish things. Below appears a bit more information about each of these implementations. The Haskell mailing list ~~~~~~~~~~~~~~~~~~~~~~~~ There is an electronic mailing list to discuss technical issues related to Haskell. To join this list, send your request to "[EMAIL PROTECTED]" (Europe and Australasia) or "[EMAIL PROTECTED]" (rest of world) as appropriate. Standard archive sites for Haskell stuff ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can use anonymous FTP (username: anonymous; password: your e-mail address) to these hosts, where you will find things in "pub/haskell" and its subdirectories. Site Host name Raw IP address Chalmers animal.cs.chalmers.se 18.104.22.168 Glasgow ftp.dcs.glasgow.ac.uk 22.214.171.124 Yale nebula.cs.yale.edu 126.96.36.199 DETAILS OF IMPLEMENTATIONS ~~~~~~~~~~~~~~~~~~~~~~~~~~ The Glasgow compiler ~~~~~~~~~~~~~~~~~~~~ The Glasgow Haskell compiler has the following attributes: * Freely available (see below). * Written in Haskell. * Generates C as its target code -- hence highly portable. * Specifically designed to act as a "motherboard" into which others can "plug in" their own strictness analyser, profiler, front end, back end, or other special pass. * Internally, it uses the second-order polymorphic lambda calculus to preserve correct type information in the face of substantial program transformations. * Back end based on the Spineless Tagless G-machine -- our abstract machine for non-strict functional languages. (Paper available.) * Plants code to gather profiling information, of two sorts. First, low-level counts of various aspects of the abstract machine model. Second, and more interesting, programmer-level space and time profiling of "cost centres". (Paper available.) * Heavily configurable runtime system. For example, the "motherboard" comes with three different garbage collectors: two-space, one-space compacting, and Appel-style generational. * New monad-based model for input/output, which allows calls to arbitrary C procedures without losing referential transparency. Based on this technology, the entire I/O system is implemented in Haskell itself. Current status (June 1992): Generates code which runs, but which is larger and slower than hbc. If you are a Haskell programmer you don't want it yet. If you are a Haskell implementor, it is useful now. How to get the compiler and papers: Use anonymous FTP to one of the standard archive sites, with pub/haskell/glasgow being a particularly likely place to find things. ftp.dcs.glasgow.ac.uk is the most likely to have up-to-date things (obviously); it also has a Glasgow-specific directory, pub/glasgow-fp. The same stuff is available by NIFTP (UK only); send email to haskell-request if you need details. The Chalmers compiler: hbc/hbi ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The Chalmers Haskell-B compiler implements a dialect of Haskell. It is written by Lennart Augustsson, and based on the classic LML compiler by Augustsson and Johnsson. Status (as of August 1992): * Current version is 0.998.1. * Has several optional extensions to Haskell. The most interesting one is probably the existentially quantified types. * Can generate code for both time and heap profiling. * The interactive system hbi is an interpreter for Haskell, but it can also load code compiled with hbc. * Generates native code and runs on SUN3, SUN4, DECstation, VAX, ARM, and Sequent Symmetry. (Unsupported versions for NS32000, RT/PC, and Cray.) Soon available on RS6000. Contact: Lennart Augustsson Chalmers University Informationsbehandling Goteborg SWEDEN [EMAIL PROTECTED] The hbc distribution is available from the standard archive sites, in pub/haskell/chalmers. The Yale compiler ~~~~~~~~~~~~~~~~~ The Yale Haskell compiler (yh2.0) has the following attributes: * Freely available. * Written in Lisp (Common Lisp, EuLisp, or Scheme). * Generates Lisp as its target code -- hence highly portable. * Interactive programming environment based on the Emacs editor. Comes with an online Haskell tutorial. * Easy to call out to Lisp (or C, depending on the Lisp being used) functions. * Fast compilation. * High quality code. The ultimate code quality will depend on the underlying Lisp system but the Yale compiler will generate declarations which will allow the more sophisticated Lisp systems to produce the best possible code. The Yale system should be ready for general release in August 1992. Watch for announcements to the mailing list and comp.lang.functional. For more information contact [EMAIL PROTECTED] Future releases of Yale Haskell (probably Fall 92) are expected to include the following features: * Compiler passes and data structures will be accessable from Haskell, allowing new or different phases written in Haskell to be inserted. * Strict data constructors * Dynamic typing * Interfaces tuned to the Mac and PC * More support for separate compilation and large scale Haskell programs. * Compiler pragmas to create specialized versions of overloaded operators. * Language extensions to support efficient manipulation of state (including arrays). Contact: John Peterson Yale University Department of Computer Science New Haven, CT 06520 UNITED STATES [EMAIL PROTECTED] The Gofer interpreter ~~~~~~~~~~~~~~~~~~~~~ The Gofer interpreter implements a subset of Haskell, and uses an experimental variant of Haskell's innovative `type classes' for overloading. It extends Haskell in some ways, and subsets it in others. The most significant features of Haskell not currently supported are: modules, arrays, overloaded numeric constants, default declarations, derived instances and contexts in datatype definitions. It runs on Sun3's, Sun4's, and IBM PC's, Macs, Atari ST, Commodore Amiga, Acorn Archimedes and others. Contact: Mark Jones Programming Research Group Oxford University Oxford OX1 3QD UNITED KINGDOM [EMAIL PROTECTED] (Mark is moving to Yale in Sept 92.) The Gofer distribution is available from the standard archive sites (see above), in pub/haskell/gofer.