[Caml-list] OCaml 3.01 released

[Xavier Leroy <Xavier.Leroy@inria.fr>]

Version 3.01 of the Objective Caml system is now available from the
usual places:

        http://caml.inria.fr/ocaml/distrib.html
        ftp://ftp.inria.fr/lang/caml-light/

No major novelties in this release (see detailed list below), but a
few convenience features were added:

  - variables in "or" patterns, as in "match l with [t] | [_;t] -> ... t ...";
  - "include" in structures to reexport all components of a structure
    inside another structure;
  - variance annotations on abstract type declarations;
  - the bytecode interpreter can print a call stack backtrace when
    an uncaught exception aborts the program;
  - option "-I +<subdir>" to refer to a subdirectory of the standard library
    directory.

In addition, compilation of pattern-matching was revised and generates
much better code on complex matchings, especially those involving "or"
patterns.  Finally, the system was ported to Cygwin (Cygnus/RedHat's
Unix compatibility environment for Windows), and Cygwin binaries are
distributed along with the previous native Win32 port.

For general info on Objective Caml, see http://caml.inria.fr.  Bug
reports go to caml-bugs@inria.fr, questions to caml@inria.fr,
and general discussions to the mailing-list caml-list@inria.fr or the
comp.lang.ml newsgroup.

- Xavier Leroy, for the Objective Caml team.


Objective Caml 3.01:
--------------------

New language features:
- Variables are allowed in "or" patterns, e.g.
     match l with [t] | [_;t] -> ... t ...
- "include <structure expression>" to re-export all components of a
  structure inside another structure.
- Variance annotation on parameters of type declarations, e.g.
    type (+'a,-'b,'c) t (covariant in 'a, contravariant in 'b, invariant in 'c)

New ports:
- Intel IA64/Itanium under Linux (including the native-code compiler).
- Cygwin under MS Windows.  This port is an alternative to the earlier
  Windows port of OCaml, which relied on MS compilers; the Cygwin
  Windows port does not need MS Visual C++ nor MASM, runs faster
  in bytecode, and has a better implementation of the Unix library, 
  but currently lacks threads and COM component support.

Type-checking:
- Relaxed "monomorphic restriction" on type constructors in a 
  mutually-recursive type definition, e.g. the following is again allowed
    type u = C of int t | D of string t and 'a t = ...
- Fixed name-capture bug in "include SIG" and "SIG with ..." constructs.
- Improved implicit subtypes built by (... :> ty), closer to intuition.
- Several bug fixes in type-checking of variants.
- Typing of polymorphic variants is more restrictive:
   do not allow conjunctive types inside the same pattern matching.
   a type has either an upper bound, or all its tags are in the lower bound.
  This may break some programs (this breaks lablgl-0.94).

Both compilers:
- Revised compilation of pattern matching.
- Option -I +<subdir> to search a subdirectory <subdir> of the standard
  library directory (i.e. write "ocamlc -I +labltk" instead of 
  "ocamlc -I /usr/local/lib/ocaml/labltk").
- Option -warn-error to turn warnings into errors.
- Option -where to print the location of the standard library directory.
- Assertions are now type-checked even if the -noassert option is given,
  thus -noassert can no longe change the types of modules.

Bytecode compiler and bytecode interpreter:
- Print stack backtrace when a program aborts due to an uncaught exception
  (requires compilation with -g and running with ocamlrun -b or
   OCAMLRUNPARAM="b=1").

Native-code compiler:
- Better unboxing optimizations on the int32, int64, and nativeint types.
- Tail recursion preserved for functions having more parameters than
  available registers (but tail calls to other functions are still
  turned off if parameters do not fit entirely in registers).
- Fixed name-capture bug in function inlining.
- Improved spilling/reloading strategy for conditionals.
- IA32, Alpha: better alignment of branch targets.
- Removed spurious dependency on the -lcurses library.

Toplevel environment:
- Revised handling of top-level value definitions, allows reclaimation
  of definitions that are shadowed by later definitions with the same names.
  (E.g. "let x = <big list>;; let x = 1;;" allows <big list> to be reclaimed.)
- Revised the tracing facility so that for standard library functions,
  only calls from user code are traced, not calls from the system.
- Added a "*" prompt when within a comment.

Runtime system:
- Fixed portability issue on bcopy() vs memmove(), affecting Linux RedHat 7.0
  in particular.
- Structural comparisons (=, <>, <, <=, >, >=, compare) reimplemented
  so as to avoid overflowing the C stack.
- Input/output functions: arrange so that reads and writes on closed
  in_channel or out_channel raise Sys_error immediately.

Standard library:
- Module Gc: changed some counters to float in order to avoid overflow;
    added alarms
- Module Hashtbl: added Hashtbl.replace.
- Module Int64: added bits_of_float, float_of_bits (access to IEEE 754
    representation of floats).
- Module List:  List.partition now tail-rec; 
    improved memory behavior of List.stable_sort.
- Module Nativeint: added Nativeint.size (number of bits in a nativeint).
- Module Obj: fixed incorrect resizing of float arrays in Obj.resize.
- Module Pervasives: added float constants "infinity", "neg_infinity", "nan";
    added a "classify_float" function to test a float for NaN, infinity, etc.
- Pervasives.input_value: fixed bug affecting shared custom objects.
- Pervasives.output_value: fixed size bug affecting "int64" values.
- Pervasives.int_of_string, {Int32,Int64,Nativeint}.of_string:
  fixed bug causing bad digits to be accepted without error.
- Module Random: added get_state and set_state to checkpoint the generator.
- Module Sys: signal handling functions are passed the system-independent
  signal number rather than the raw system signal number whenever possible.
- Module Weak: added Weak.get_copy.

Other libraries:
- Bigarray: added Bigarray.reshape to take a view of the elements of a
  bigarray with different dimensions or number of dimensions;
  fixed bug causing "get" operations to be unavailable in custom
  toplevels including Bigarray.
- Dynlink: raise an error instead of crashing when the loaded module
  refers to the not-yet-initialized module performing a dynlink operation.
- Bytecode threads: added a thread-safe version of the Marshal module;
    fixed a rare GC bug in the thread scheduler.
- POSIX threads: fixed compilation problem with threads.cmxa.
- Both thread libraries: better tail-recursion in Event.sync.
- Num library: fixed bug in square roots (Nat.sqrt_nat, Big_int.sqrt_big_int).

Tools:
- ocamldep: fixed missing dependencies on labels of record patterns and
    record construction operations

Win32 port:
- Unix.waitpid now implements the WNOHANG option.

Mac OS ports:
- Mac OS X public beta is supported.
- Int64.format works on Mac OS 8/9.
-------------------
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