The Glasgow Haskell Compiler -- version 0.16 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The second public release of the Glasgow Haskell Compiler is now available (GHC, version 0.16). Binaries (recommended) and source are freely available by FTP; details appear below. GHC 0.16 is still alpha-quality software. This release in an interim measure, not as solid as I would prefer. However, a lot has gone in since December. The profiling system is Way Cool. The compiler now has a strictness analyser and an update analyser. Compiled programs tend to run faster. Compilation speed is worse. Bugs remain, but they tend to be work-around-able. To run this release, you need a Sun4 or Sun3, probably with 16+MB memory, and GNU C (gcc), version 2.1 or greater, and "perl". This system can be built from source using: itself (most likely to succeed), the previous GHC release (0.10) [least likely], or the Chalmers HBC compiler [in-between]. Please see the appropriate documentation for details. Please report bugs to glasgow-haskell-bugs@dcs.glasgow.ac.uk and direct general queries to glasgow-haskell-request@. Will Partain (typist for the AQUA [formerly GRASP] project) .................................................................... Why a Haskell programmer might want to use GHC ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * GHC provides an extensible I/O system, based on a "monad" [1]. (The standard Haskell I/O system is built on this foundation.) * A number of significant language extensions are implemented: - Fully fledged unboxed data types [2]. - Ability to write arbitrary in-line C-language code, using the I/O monad to retain referential transparency. - Incrementally-updatable arrays, also embedded in a monad. - Mutable reference types. * A new profiling system is supplied, which enables you to find out which bits of your program are eating both *time* and the *space* [3]. * By default, the system uses a generational garbage collector which lets you run programs whose live data is significantly larger than the physical memory size before thrashing occurs. (Conventional 2-space GC starts thrashing when the live data gets to about half the physical memory size.) * Good error messages. Well, fairly good error messages. Line numbers are pretty accurate, and during type checking you get several (accurate) error reports rather than just one. * Performance: programs compiled with GHC "often" beat Chalmers-HBC-compiled ones. If you find programs where HBC wins, please report it to us, as a bug :-). Why a functional-language implementor might want to use GHC ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * We have tried very hard to write the compiler in a modular and well-documented way, so that other researchers can modify and extend it. One of our goals is specifically to provide a framework to support others' work. Several people are already using it in this way. * Highly configurable runtime system. Heavy use of C macros means that you can modify much of the storage representation without telling the compiler. For example, the system comes with 4 different garbage collectors! (all working) * Internals: extensive use of the second-order lambda calculus as an intermediate code; the Spineless Tagless G-machine as evaluation model [4]. * Various performance-measurement hooks. Main shortcomings ~~~~~~~~~~~~~~~~~ * No interactive system. This is a batch compiler only. (Any volunteers?) * Compiler is greedy on resources. Going via C doesn't help here. * This system should run on any Unix box. We haven't had time to do any non-Sun ports. Help or prodding welcome. References ~~~~~~~~~~ All these papers come with the distribution [in ghc/docs/papers]. [1] "Imperative functional programming", Peyton Jones & Wadler, POPL '93 [2] "Unboxed data types as first-class citizens", Peyton Jones & Launchbury, FPCA '91 [3] "Profiling lazy functional languages", Sansom & Peyton Jones, Glasgow workshop '92 [4] "Implementing lazy functional languages on stock hardware", Peyton Jones, Journal of Functional Programming, Apr 1992 How to get it ~~~~~~~~~~~~~ This release is available, in whole or in part, from the usual Haskell anonymous FTP sites, in the directory pub/haskell/glasgow: ftp.dcs.glasgow.ac.uk (130.209.240.50) ftp.cs.chalmers.se (129.16.225.66) nebula.cs.yale.edu (128.36.13.1) We are mirrored by src.doc.ic.ac.uk, in computing/programming/languages/haskell/glasgow, and you can get files from there by every means known to humanity. These are the available files (.Z for compressed, .gz for gzipped) -- some are `on demand', ask if you don't see them: ghc-0.16-bin-sun4.tar.{Z,gz} A binary distribution -- avoid compiling altogether! For SunOS 4.1.x; assumes you have GNU C (gcc) version 2.x around... ghc-0.16-src.tar.gz The basic source distribution; about 3MB. ghc-0.16-hi-files-{hbc,ghc-0.10}.tar.gz Interface files for the compiler proper (ghc/compiler/*/*.hi), to be used if booting with either HBC or GHC version 0.10. (The distributed .hi files assume GHC version 0.16.) ghc-0.16-hc-files.tar.gz The intermediate C files for the compiler proper, the prelude, and `Hello, world'. Used when porting. ghc-0.16-patch-* Patches to the original distribution. There are none to start with, of course, but there might be by the time you grab the files. Please check for them. There are no diffs from version 0.10, as they would be laughably huge. Once you have the distribution, please follow the pointers in the ghc/README file to find all of the documentation in and about this release.