<html>
<head>
<title>Module Pycaml</title>
</head>
<body>
<table border=0 width="100%"><tr><td bgcolor="#c0c0c0">
<h1>Pycaml</h1>
</td></tr></table>
<p>
<h2>What is Pycaml</h2>
A library written by <a href=mailto:arty@users.sourceforge.net>
arty@users.sourceforge.net</a> which follows the Python/C API as
closely as possible, while
providing equivalent functionality for objective caml.  This is built
against python 2.x and Ocaml 3.04.<p>  It is intended to allow users to
build native ocaml libraries and use them from python, and alternately,
in order to allow ocaml users to benefit from linkable libraries provided
for python.<p>
I created this library in order to take advantage of python binding for
certain native libraries from ocaml.  While it is true that I could have
written new interfaces specifically for ocaml, the python interface is
sufficient for my needs, and this project was easier.<p>

Please edit the <tt>Makefile</tt> to put in your system's libraries used for
compiling programs embedded with python.  This library compiles on most
linux boxes without modification.  The python interpreter is used to determine
the path to the python library and must be in your path when you run make.
<p>

<b>Get the distribution here:</b><a href=pycaml.tar.gz>pycaml.tar.gz</a><p>

Because these are made to closely mirror the python API, the user should
become familiar with the python API.<p>
Given Ocaml parameter passing convention, it was convenient to pass multiple
arguments as members of a tuple, but single arguments without.  Consequently,
functions with arity 1, such as pytuple_new are called as<p>
<pre>
  pytuple_new 3 ;;
</pre><p>
And functions with more arguments are called as<p>
<pre>
  pydict_getitemstring (dict,"keystring") ;;
</pre>

<h2>Module Pycaml</h2>

<h3>Visible Types</h3>

<table border=0>
<tr bgcolor="#c0c0c0"><td>type</td><td width="100%">pyobject</td></tr>
<tr><td colspan=2>
The abstract type of python objects.
</td></tr>
<tr bgcolor="#c0c0c0"><td>type</td><td>pyobject_type =</td></tr>
<tr><td align=right></td><td>TupleType</td></tr>
<tr><td align=right>|</td><td>StringType</td></tr>
<tr><td align=right>|</td><td>IntType</td></tr>
<tr><td align=right>|</td><td>FloatType</td></tr>
<tr><td align=right>|</td><td>ListType</td></tr>
<tr><td align=right>|</td><td>NoneType</td></tr>
<tr><td align=right>|</td><td>CallableType</td></tr>
<tr><td align=right>|</td><td>ModuleType</td></tr>
<tr><td align=right>|</td><td>ClassType</td></tr>
<tr><td align=right>|</td><td>TypeType</td></tr>
<tr><td align=right>|</td><td>OtherType</td></tr>
<tr><td colspan=2>
The type representing the range of types available to python programs.
Values of this type are provided by the pytype function, and identify the
python type of opaque pyobject objects.
</td></tr></table>

<h3>Supported Functions from the Python/C API</h3>
In each case, the signature of the function is unchanged from the Python/C
API except for the case of 'out' pointer to pointer parameters; 
in the case of a single return, the returned value is copied, otherwise, 
a tuple is created with copies of all output parameters.  In the case of
zero parameter, or void return, unit is used.<p>
In python API functions that take a FILE *, an int file descriptor is used
instead such as those returned by the Unix library.<p>

<h4>fun unit -> unit</h4>
py_initialize, py_finalize, pyerr_print, pyerr_clear, pyimport_cleanup
<h4>fun int -> unit</h4>
py_exit, pyerr_printex
<h4>fun string -> unit</h4>
py_setprogramname, py_setpythonhome
<h4>fun unit -> int</h4>
py_isinitialized, pyeval_getrestricted
<h4>fun string -> int</h4>
pyrun_simplestring, pyimport_importfrozenmodule,
<h4>fun (int * string) -> int</h4>
pyrun_anyfile, pyrun_simplefile, pyrun_interactiveone, pyrun_interactiveloop,
py_fdisinteractive
<h4>fun (int * string * int) -> int</h4>
pyrun_anyfileex, pyrun_simplefileex
<h4>fun unit -> string</h4>
py_getprogramname, py_getpthonhome, py_getprogramfullpath, py_getprefix,
py_getexecprefix, py_getpath, py_getversion, py_getplatform, py_getcopyright,
py_getcompiler, py_getbuildinfo
<h4>fun (string * int * pyobject * pyobject) -> pyobject</h4>
pyrun_string
<h4>fun (int * string * int * pyobject * pyobject) -> pyobject</h4>
pyrun_file
<h4>fun (int * string * int * pyobject * pyobject * int) -> pyobject</h4>
pyrun_fileex
<h4>fun (string * string * int) -> pyobject</h4>
py_compilestring
<h4>fun (pyobject * int * int) -> int</h4>
pyobject_print, pytuple_getslice, pysequence_getslice</h4>
<h4>fun pyobject -> pyobject</h4>
pyobject_repr, pyobject_str, pyobject_unicode, pydict_keys, pydict_values,
pydict_items, pydict_copy, pymodule_getdict, pymethod_function, pymethod_self,
pymethod_class, pymodule_getdict, pyimport_reloadmodule, pyobject_type, 
pynumber_negative, pynumber_positive, pynumber_absolute, pynumber_invert,
pynumber_int, pynumber_long, pynumber_float, pysequence_tuple, pysequence_list
<h4>fun (pyobject * pyobject * int) -> pyobject</h4>
pyobject_richcompare
<h4>fun (pyobject * string) -> pyobject</h4>
pyobject_getattrstring, pydict_getitemstring, pysequence_fast, 
pymapping_haskeystring, pymapping_getitemstring
<h4>fun (pyobject * pyobject) -> pyobject</h4>
pyobject_getattr, pystring_format, pydict_getitem, pyinstance_newraw, 
pyeval_callobject, pyobject_getitem, pyobject_delitem, pynumber_add,
pynumber_subtract, pynumber_multiply, pynumber_divide, pynumber_remainder,
pynumber_divmod, pynumber_lshift, pynumber_rshift, pynumber_and, pynumber_xor,
pynumber_or, pynumber_inplaceadd, pynumber_inplacesubtract, pynumber_inplacemultiply, pynumber_inplacedivide, pynumber_inplaceremainder, pynumber_inplacelshift, pynumber_inplacershift, pynumber_inplaceand, pynumber_inplacexor, pynumber_inplaceor, pysequence_concat, pysequence_inplaceconcat
<h4>fun pyobject -> int</h4>
pyobject_istrue, pyobject_not, pycalable_check, pystring_size, pydict_size,
pytuple_new, pyerr_exceptionmatches, pyobject_size, pynumber_check, 
pysequence_check, pysequence_size, pysequence_length, pymapping_check,
pymapping_size, pymapping_length, pyint_asint
<h4>fun (pyobject * pyobject) -> int</h4>
pyobject_compare, pyobject_hasattr, pydict_delitem, 
pyerr_givenexceptionmatches, pysequence_count, pysequence_contains, 
pysequence_in, pysequence_index, pymapping_haskey
<h4>fun (pyobject * pyobject * int) -> int</h4>
pyobject_richcomparebool, pysequence_delitem
<h4>fun (pyobject * string * pyobject) -> int</h4>
pyobject_setattrstring, pydict_setitemstring
<h4>fun (pyobject * string) -> int</h4>
pyobject_hasattrstring, pydict_delitemstring, pysequence_inplacerepeat
<h4>fun (pyobject * pyobject) -> (pyobject * pyobject)</h4>
pynumber_coerce, pynumber_coerceex
<h4>fun (pyobject * pyobject * pyobject) -> int</h4>
pyobject_setattr, pydict_setitem, pyobject_setitem
<h4>fun pyobject -> int64</h4>
pyobject_hash, pyint_aslong
<h4>fun pyobject -> string</h4>
pystring_asstring, pymodule_getname, pymodule_getfilename
<h4>fun (pyobject * pyobject) -> pyobject</h4>
pystring_concat, pystring_concatanddel
<h4>fun string -> pyobject</h4>
pystring_fromstring, pymodule_new, pyimport_addmodule, pyimport_importmodule,
pyimport_import
<h4>fun unit -> pyobject</h4>
pydict_new, pyerr_occurred, pyimport_getmoduledict, pyeval_getbuiltins,
pyeval_getglobals, pyeval_getlocals, pyeval_getframe
<h4>fun pyobject -> unit</h4>
pydict_clear, pyerr_setnone
<h4>fun (pyobject * int) -> (pyobject * pyobject * int)</h4>
pydict_next
<h4>fun int64 -> pyobject</h4>
pyint_fromlong
<h4>fun unit -> int64</h4>
pyint_getmax
<h4>fun float -> pyobject</h4>
pyfloat_fromdouble
<h4>fun pyobject -> float</h4>
pyfloat_asdouble
<h4>fun int -> pyobject</h4>
pytuple_new, pyint_fromint
<h4>fun (pyobject * int) -> pyobject</h4>
pytuple_getitem, pysequence_repeat, pysequence_getitem
<h4>fun (pyobject * int * pyobject) -> int</h4>
pytuple_setitem, pysequence_setitem, pymapping_setitem
<h4>fun (pyobject * pyobject * pyobject) -> pyobject</h4>
pyslice_new, pyclass_new, pyinstance_new, pymethod_new, 
pyeval_callobjectwithkeywords, pynumber_power, pynumber_inplacepower
<h4>fun (pyobject * int) -> (int * int * int)</h4>
pyslice_getindices
<h4>fun (int * int * int * int) -> pyobject</h4>
pyrange_new
<h4>fun (pyobject * pyobject) -> unit</h4>
pyerr_setobject
<h4>fun (pyobject * string) -> unit</h4>
pyerr_setstring
<h4>fun (pyobject * pyobject * pyobject) -> (pyobject * pyobject * pyobject)</h4>
pyerr_fetch, pyerr_normalizeexception
<h4>fun (pyobject * pyobject * pyobject) -> unit</h4>
pyerr_restore
<h4>fun (pyobject * string) -> pyobject</h4>
pyimport_execcodemodule
<h4>fun (string * pyobject * string) -> pyobject</h4>
pyimport_execcodemoduleex
<h4>fun (string * pyobject * pyobject * pyobject) -> pyobject</h4>
pyimport_importmoduleex
<h4>fun pyobject -> string</h4>
pyobject_ascharbuffer, pyobject_asreadbuffer, pyobject_aswritebuffer
<h4>fun (pyobject * int * int * pyobject) -> int</h4>
pysequence_setslice
<h4>fun (pyobject * int * int) -> int</h4>
pysequence_delslice

<h3>Unique Functions Needed for Ocaml</h3>
In addition to the functions in the usual library, several new functions are
provided which give specific support for ocaml.<p>

<table border=0 width=100%>
<tr bgcolor="#c0c0c0">
<td><b>pytuple_toarray</b></td>
<td>pyobject -> pyobject array</td></tr>
<tr><td colspan=2>
Convert a python tuple to an ocaml array containing the same items.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pywrap_closure</b></td><td>(pyobject -> pyobject) -> pyobject</td></tr>
<tr><td colspan=2>
Create a python callable object from a closure.  The closure receives the
argument tuple from the invocation and returns a pyobject.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pywrap_value</b></td><td>'a -> pyobject</td></tr>
<tr><td colspan=2>
Create a simple void * style wrapping around an ocaml object.  The object
may be retrieved with <tt>pyunwrap_value : pyobject -> 'a</tt>.  Use this
to enclose an ocaml data structure in python to be used later.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pynull</b></td><td>unit -> pyobject</td></tr>
<tr><td colspan=2>
Generate the null PyObject * and return it.  This may sound dangerous, but
it is used by library calls to indicate errors to the python system.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pynone</b></td><td>unit -> pyobject</td></tr>
<tr><td colspan=2>
Generate a reference to the Py_None object.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pytuple_fromarray</b></td>
<td>pyobject array -> pyobject</td></tr>
<tr><td colspan=2>
Create a pytuple (as would be used for a function call) from the given
array.  This may be used to implement varargs calls on python functions,
and for other purposes.
</td></tr>
<tr bgcolor="#c0c0c0">
<td><b>pytuple_empty</b></td>
<td>pyobject array -> pyobject</td></tr>
<tr><td colspan=2>
Shortcut for <tt>pytuple_new 0</tt>
</td></tr>

<tr bgcolor="#c0c0c0">
<td><b>pytuple_fromsingle</b></td>
<td>pyobject -> pyobject</tt></td></tr>
<tr><td colspan=2>
Create a tuple with the single given object inside.  Use this to create
single element tuples as for a function call with one argument.
</td></tr>

<tr bgcolor="#c0c0c0">
<td><b>pytuple<i>1-5</i></b></td>
<td>(pyobject * ...) -> pyobject</tt></td></tr>
<tr><td colspan=2>
Create a python tuple that has the same contents as the given ocaml tuple.
</td></tr>

<tr bgcolor="#c0c0c0">
<td><b>pytype</b></td>
<td>pyobject -> pyobject_type</tt></td></tr>
<tr><td colspan=2>
Determine roughly which type family the given value belongs to.  For example,
<tt>pytype (pystring_fromstring "hi")</tt> yields <tt>StringType</tt>.
</td></tr>
</table>

<h3>Sample Application</h3>
This is the sample application that I developed the library with.  It 
illustrates a python function call, as well as a call back into ocaml.
The first form is used in cases where python libraries are to be used
from ocaml, and the second would be used to produce native libraries in
ocaml.<p>

<pre>
open Pycaml ;;

let colorsys = pyimport_importmodule "colorsys"
let dict = pymodule_getdict colorsys

let triplet = pytuple3 (pyfloat_fromdouble 1.0,
			pyfloat_fromdouble 0.5,
			pyfloat_fromdouble 0.2) ;;

let rgbtoyiq = pydict_getitemstring (dict,"rgb_to_yiq")
let triplet = pyeval_callobject (rgbtoyiq,triplet)

let _ = print_endline ((string_of_float
			  (pyfloat_asdouble (pytuple_getitem (triplet,0)))) ^ 
		       " " ^
		       (string_of_float
			  (pyfloat_asdouble (pytuple_getitem (triplet,1)))) ^
		       " " ^
		       (string_of_float
			  (pyfloat_asdouble (pytuple_getitem (triplet,2))))) ;;

let x = pywrap_closure 
    (fun x -> print_string (pystring_asstring (pytuple_getitem (x,0))) ; 
      pynone ())

let _ = pyeval_callobject 
    (x,pytuple_fromsingle (pystring_fromstring "hi there"))
</pre>
</body>
</html>
