module Marshal:Marshaling of data structures.sig..end
This module provides functions to encode arbitrary data structures as sequences of bytes, which can then be written on a file or sent over a pipe or network connection. The bytes can then be read back later, possibly in another process, and decoded back into a data structure. The format for the byte sequences is compatible across all machines for a given version of OCaml.
   Warning: marshaling is currently not type-safe. The type
   of marshaled data is not transmitted along the value of the data,
   making it impossible to check that the data read back possesses the
   type expected by the context. In particular, the result type of
   the Marshal.from_* functions is given as 'a, but this is
   misleading: the returned OCaml value does not possess type 'a
   for all 'a; it has one, unique type which cannot be determined
   at compile-type.  The programmer should explicitly give the expected
   type of the returned value, using the following syntax:
(Marshal.from_channel chan : type).
   Anything can happen at run-time if the object in the file does not
   belong to the given type.Marshal.to_channel
   and Marshal.from_channel must be opened in binary mode, using e.g.
   open_out_bin or open_in_bin; channels opened in text mode will
   cause unmarshaling errors on platforms where text channels behave
   differently than binary channels, e.g. Windows.type | | | No_sharing | (* | Don't preserve sharing | *) | 
| | | Closures | (* | Send function closures | *) | 
Marshal.to_* functions below.val to_channel : out_channel -> 'a -> extern_flags list -> unitMarshal.to_channel chan v flags writes the representation
   of v on channel chan. The flags argument is a
   possibly empty list of flags that governs the marshaling
   behavior with respect to sharing and functional values.
   If flags does not contain Marshal.No_sharing, circularities
   and sharing inside the value v are detected and preserved
   in the sequence of bytes produced. In particular, this
   guarantees that marshaling always terminates. Sharing
   between values marshaled by successive calls to
   Marshal.to_channel is not detected, though.
   If flags contains Marshal.No_sharing, sharing is ignored.
   This results in faster marshaling if v contains no shared
   substructures, but may cause slower marshaling and larger
   byte representations if v actually contains sharing,
   or even non-termination if v contains cycles.
   If flags does not contain Marshal.Closures,
   marshaling fails when it encounters a functional value
   inside v: only ``pure'' data structures, containing neither
   functions nor objects, can safely be transmitted between
   different programs. If flags contains Marshal.Closures,
   functional values will be marshaled as a position in the code
   of the program. In this case, the output of marshaling can
   only be read back in processes that run exactly the same program,
   with exactly the same compiled code. (This is checked
   at un-marshaling time, using an MD5 digest of the code
   transmitted along with the code position.)
val to_string : 'a -> extern_flags list -> stringMarshal.to_string v flags returns a string containing
   the representation of v as a sequence of bytes.
   The flags argument has the same meaning as for
   Marshal.to_channel.val to_buffer : string -> int -> int -> 'a -> extern_flags list -> intMarshal.to_buffer buff ofs len v flags marshals the value v,
   storing its byte representation in the string buff,
   starting at character number ofs, and writing at most
   len characters.  It returns the number of characters
   actually written to the string. If the byte representation
   of v does not fit in len characters, the exception Failure
   is raised.val from_channel : in_channel -> 'aMarshal.from_channel chan reads from channel chan the
   byte representation of a structured value, as produced by
   one of the Marshal.to_* functions, and reconstructs and
   returns the corresponding value.val from_string : string -> int -> 'aMarshal.from_string buff ofs unmarshals a structured value
   like Marshal.from_channel does, except that the byte
   representation is not read from a channel, but taken from
   the string buff, starting at position ofs.val header_size : intMarshal.header_size is the size, in characters, of the header.
   Marshal.data_size buff ofs is the size, in characters,
   of the data part, assuming a valid header is stored in
   buff starting at position ofs.
   Finally, Marshal.total_size buff ofs is the total size,
   in characters, of the marshaled value.
   Both Marshal.data_size and Marshal.total_size raise Failure
   if buff, ofs does not contain a valid header.
   To read the byte representation of a marshaled value into
   a string buffer, the program needs to read first
   Marshal.header_size characters into the buffer,
   then determine the length of the remainder of the
   representation using Marshal.data_size,
   make sure the buffer is large enough to hold the remaining
   data, then read it, and finally call Marshal.from_string
   to unmarshal the value.
val data_size : string -> int -> intMarshal.header_size.val total_size : string -> int -> intMarshal.header_size.