Typing unmarshalling without marshalling types

[Michel Mauny <Michel.Mauny@ensta.fr>]

Dear all,

We are pleased to announce a patch for Objective Caml that provides
type safe unmarshalling functions. In short, the main features are:

  - a type for type representations ('a tyrepr, a singleton type)

  - unmarshalling functions like the following:

       SafeUnmarshal.from_string:  'a tyrepr -> string -> int -> 'a

such that

       SafeUnmarshal.from_string ty str off

returns the value whose marshal is the string str (starting at offset
off) and gives it the type (represented by) ty, if possible. If the
value cannot be of type ty, the function fails.

For instance,

       SafeUnmarshal.from_string  [^ ( float *  int ) ^] str 0

asks the (memory representation of the) unmarshalled value to be
compatible with the type (float * int).

  - there is no type information in the marshalled data: marshalling
functions are not modified by this patch.

  - classical (unsafe) unmarshalling functions are still available.

The easiest way to obtained a patched version of OCaml is to download:

  http://www.pps.jussieu.fr/~henry/marshal/src/make_source_tree.sh

and to execute the following sequence:

./make_source_tree.sh ocaml-ty && cd ocaml-ty && ./configure && make world &&
make -C otherlibs/safe_unmarshaling top

The last command of the sequence runs the patched OCaml toplevel.

More information at:

  http://www.pps.jussieu.fr/~henry/marshal/

Have fun,

-- Grégoire Henry and Michel Mauny