From: Xavier Leroy <xleroy@pauillac.inria.fr>
Message-Id: <9501101913.AA00456@pauillac.inria.fr>
Subject: first beta release of Caml Light 0.7
To: caml-list@pauillac.inria.fr
Date: Tue, 10 Jan 1995 20:13:00 +0100 (MET)
It is my pleasure to announce the first beta release of Caml Light
version 0.7. The release is available by anonymous FTP:
host: ftp.inria.fr
directory: lang/caml-light/Release7beta
This is still beta software: it is reasonably stable and works fine
for us, but still may change before the final release (which is
scheduled for end of February). Only the Unix version is distributed;
the Macintosh and PC versions have not been updated yet.
A detailed list of changes since release 0.61 is included at the end
of this message. In short: there are many new features,
many new contributed tools and libraries, and a few incompatibilities
with the previous release.
As with all beta releases, this release will be useful only if there
are enough brave users that compile it and give it a try. You will
help us a lot if you do some of the following:
* Run a significant body of Caml code through it and report if you had
serious difficulties with the incompatibilities.
* Exercise the new features and tools.
* Compile the system on "exotic" platforms. We develop under SunOS
4.1.3 and DEC OSF1 2.0, with frequent tests under Ultrix 4.1 and
Linux; anything else is "exotic" for us and worth a try.
* Read carefully the changed parts of the documentation.
* Provide translations of error messages to more languages.
* Make precise bug reports to caml-light@pauillac.inria.fr.
Your help in making a better Caml Light will be appreciated.
- Xavier Leroy
----------------------------------------------------------------------
Detailed list of changes:
* Source-level debugger with replay capabilities. Compiler support for
the debugger added.
* New contributed libraries and tools:
- a complete X-windows toolkit based on TCL/TK.
- a profiler for Caml Light programs (execution counts)
- lorder: determine ordering of .zo files at link-time
* Polymorphism is now restricted to values (let x = e generalizes the type of
x only if e is syntactically a value, e.g. a constant, a variable, a
function, a tuple of values, etc). This ensures correct, type-safe handling
of polymorphic mutable structures.
* "Guards" in pattern-matching (match ... with pat when cond -> expr).
* Partial matches and unused match cases are correctly detected now.
* Internationalized error messages (controlled by the LANG environment
variable; known languages so far: american english, french).
More detailed error messages.
* Various fixes in the garbage collector to fight fragmentation of the
major heap, result in major speedups for some long-running programs.
* Generic comparisons (prefix < : 'a -> 'a -> bool). Compiler optimizations
for comparisons on base types.
* Type-checker rewritten in bottom-up style instead of top-down style.
Hopefully this makes type errors more understandable.
* let rec (f : ty) = ... now supported.
* New class of infix and prefix symbols supported (e.g. *=, !!, ++, with
precedence/associativity determined by their first character).
* Syntactic sugar:
- Alternate syntax for string access and update (s.[i], s.[i] <- c).
- := can be used instead of <- in array, record and string assignment,
e.g. record.lbl := val or array.(index) := val).
- Final semicolons permitted in sequences, lists, arrays and records
(e.g. begin ...; ...; end or [1;2;]).
- Initial | permitted in pattern matchings and type definitions
(e.g. function | pat -> expr | ...
or type t = | Cstr1 | ...)
- "\/" and "/\" synonymous for "&" and "or".
* Optimized access to unqualified identifiers in symbol tables.
* Parser cleaned up a bit, reduce/reduce conflicts eliminated.
* New library modules: format (to write pretty-printers), gc (to control the
garbage collector and obtain various statistics on memory allocation).
* The toplevel pretty-prints values and types.
* New toplevel functions: install_printer (user-defined printing functions,
now type safe and associated with a type expression -- e.g. int list --
not with a type constructor -- e.g. list); set_print_depth (control
the printing depth for values).
* Better support for non-generalizable type variables in phrases:
they no longer cause an error immediately, the check is delayed till
the end of the compilation unit.
* Static type-checking of printf. User-defined printers supported in printf
formats (%a and %t).
* Parsing engine now reentrant; a camlyacc-generated parser can call
another one in one of its actions.
* Better support for 64-bit architectures: 32-bit architectures can read
values written on a file by a 64-bit architecture; max length of strings
and arrays now determined by the runtime system.
* New primitive ouput_compact_value to write arbitrary values to disk in
a more compact (but more CPU-demanding) format than output_value.
* More robust parsing of argv (some Unix kernels set argv[0] = argv[1] = file
when a #! file is run).
* CAMLRUNPARAM environment variable to set GC parameters.
* contrib/libgraph: implemented alternate event handling methods if async I/O
are not available; ask for system calls to be restarted if possible;
restart read and write system calls if interrupted.
* contrib/libnums: upgraded the bignum library; better 64-bit support
(but still has some 64-bit bugs); alternate names for num operations
(+/ -/ */ etc).
Main incompatibilities with Caml Light 0.61:
* Polymorphic generalization has been severely restricted to eliminate
unsoundness w.r.t. polymorphic mutables. As a consequence, several
"let" declarations that used to be polymorphic are now monomorphic,
which may cause type errors later. See the manual p. 54 for a complete
description of the problem and several workarounds.
* `:=' as assignment operator for record fields cause difficulties if
one of the record fields is a reference: r.lbl := v used to mean
`update the reference r.lbl with the value v', and now means
`assign the mutable field lbl of r the value v'. Consider turning
{ lbl: T ref ... } into { mutable lbl: T }. Or add extra parentheses
(r.lbl) := v to force the interpretation of `:=' as reference assignment.
* Due to the new infix operators, extra blank space sometimes needs
to be inserted, e.g. `x+!y' should now be written `x+ !y'.