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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@<same>.
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.
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