Some of the highlights in release 3.12 are:
* Polymorphic recursion is supported, using explicit type
declarations on the recursively-defined identifiers.
* First-class modules: module expressions can be embedded as
values of the core language, then manipulated like any other
first-class value, then projected back to the module level.
* New operator to modify a signature a posteriori: S with type
t := tau denotes signature S where the t type component is
removed and substituted by the type tau elsewhere.
* New notations for record expressions and record patterns:
{ lbl } as shorthand for { lbl = lbl }, and { ...; _ } marks
record patterns where some labels were intentionally omitted.
* Local open let open ... in ... now supported by popular demand.
* Type variables can be bound as type parameters to functions;
such types are treated like abstract types within the
function body, and like type variables (possibly generalized)
outside.
* The module type of construct enables to recover the module
type of a given module.
* Explicit method override using the method! keyword, with
associated warnings and errors.
(Changes that can break existing programs are marked with a "*" )
Language features:
- Addition of lazy patterns: "lazy <pat>" matches suspensions whose values,
after forcing, match the pattern <pat>.
- Introduction of private abbreviation types "type t = private <type-expr>",
for abstracting the actual manifest type in type abbreviations.
- Subtyping is now allowed between a private abbreviation and its definition,
and between a polymorphic method and its monomorphic instance.
Compilers:
- The file name for a compilation unit should correspond to a valid
identifier (Otherwise dynamic linking and other things can fail, and
a warning is emitted.)
* Revised -output-obj: the output name must now be provided; its
extension must be one of .o/.obj, .so/.dll, or .c for the
bytecode compiler. The compilers can now produce a shared library
(with all the needed -ccopts/-ccobjs options) directly.
- -dtypes renamed to -annot, records (in .annot files) which function calls
are tail calls.
- All compiler error messages now include a file name and location, for
better interaction with Emacs' compilation mode.
- Optimized compilation of "lazy e" when the argument "e" is
already evaluated.
- Optimized compilation of equality tests with a variant constant constructor.
- The -dllib options recorded in libraries are no longer ignored when
-use_runtime or -use_prims is used (unless -no_auto_link is
explicitly used).
- Check that at most one of -pack, -a, -shared, -c, -output-obj is
given on the command line.
- Optimized compilation of private types as regular manifest types
(e.g. abbreviation to float, float array or record types with only
float fields).
Native-code compiler:
- New port: Mac OS X / Intel in 64-bit mode (configure with -cc "gcc -m64").
- A new option "-shared" to produce a plugin that can be dynamically
loaded with the native version of Dynlink.
- A new option "-nodynlink" to enable optimizations valid only for code
that is never dynlinked (no-op except for AMD64).
- More aggressive unboxing of floats and boxed integers.
- Can select which assembler and asm options to use at configuration time.
Run-time system:
- New implementation of the page table describing the heap (two-level
array in 32 bits, sparse hashtable in 64 bits), fixes issues with address
space randomization on 64-bit OS (PR#4448).
- New "generational" API for registering global memory roots with the GC,
enables faster scanning of global roots.
(The functions are caml_*_generational_global_root in <caml/memory.h>.)
- New function "caml_raise_with_args" to raise an exception with several
arguments from C.
- Changes in implementation of dynamic linking of C code:
under Win32, use Alain Frisch's flexdll implementation of the dlopen
API; under MacOSX, use dlopen API instead of MacOSX bundle API.
- Programs may now choose a first-fit allocation policy instead of
the default next-fit. First-fit reduces fragmentation but is
slightly slower in some cases.
Standard library:
- Parsing library: new function "set_trace" to programmatically turn
on or off the printing of a trace during parsing.
- Printexc library: new functions "print_backtrace" and "get_backtrace"
to obtain a stack backtrace of the most recently raised exception.
New function "record_backtrace" to turn the exception backtrace mechanism
on or off from within a program.
- Scanf library: fine-tuning of meta format implementation;
fscanf behaviour revisited: only one input buffer is allocated for any
given input channel;
the %n conversion does not count a lookahead character as read.
Other libraries:
- Dynlink: on some platforms, the Dynlink library is now available in
native code. The boolean Dynlink.is_native allows the program to
know whether it has been compiled in bytecode or in native code.
- Bigarrays: added "unsafe_get" and "unsafe_set"
(non-bound-checking versions of "get" and "set").
- Bigarrays: removed limitation "array dimension < 2^31".
- Labltk: added support for TK 8.5.
- Num: added conversions between big_int and int32, nativeint, int64.
More efficient implementation of Num.quo_num and Num.mod_num.
- Threads: improved efficiency of mutex and condition variable operations;
improved interaction with Unix.fork (PR#4577).
- Unix: added getsockopt_error returning type Unix.error.
Added support for TCP_NODELAY and IPV6_ONLY socket options.
- Win32 Unix: "select" now supports all kinds of file descriptors.
Improved emulation of "lockf" (PR#4609).
Tools:
- ocamldebug now supported under Windows (MSVC and Mingw ports),
but without the replay feature. (Contributed by Dmitry Bely
and Sylvain Le Gall at OCamlCore with support from Lexifi.)
- ocamldoc: new option -no-module-constraint-filter to include functions
hidden by signature constraint in documentation.
- ocamlmklib and ocamldep.opt now available under Windows ports.
- ocamlmklib no longer supports the -implib option.
- ocamlnat: an experimental native toplevel (not built by default).
Camlp4:
* programs linked with camlp4lib.cma now also need dynlink.cma.
- split patches files
- always enable threading which has various advantages
- it fixes the build of the Tk library
- it greatly simplifies the package list handling
- it provides threading support under NetBSD 1.6/1.6.x
- correct default dependence in "buildlink2.mk" to "build"
Bump package revision because of all these changes.
