**************************************************************************
*                                                                        *
*                 ACG development toolkit                                *
*                                                                        *
*                  Copyright 2008 INRIA                                  *
*                                                                        *
*  More information on "http://acg.gforge.inria.fr/"                     *
*  License: CeCILL, see the LICENSE file or "http://www.cecill.info"     *
*  Authors: see the AUTHORS file                                         *
*                                                                        *
*                                                                        *
*                                                                        *
*                                                                        *
*  $Rev::                              $:  Revision of last commit       *
*  $Author::                           $:  Author of last commit         *
*  $Date::                             $:  Date of last commit           *
*                                                                        *
**************************************************************************

This distribution provides two executables (possibly with the .opt
extension, see the INSTALL file):

	acgc
and
	acg


************
*** acgc ***
************

acgc is a "compiler" of ACG source code, i.e. files containing
definitions of signarures and lexicons. It basically checks whether
they are correctly written (syntactically and wrt types and constant
typing) and outputs a .acgo object file. An interactive mode is
available to parse terms according to signatures.

Run

	./acgc -help

to get help

***********
*** acg ***
***********

acg is an interpreter of command meant to be useful when using
ACGs. To get a list of command, run

	./acg

then on the prompt type

	help;


Example files are given in the ./examples directory. Read the
./examples/README file


***************
* Basic usage *
***************

Let's assume you defined a file my_acg.acg in directory my_dir. A
basic usage of the acgc and acg commands could be:

$ acgc -o my_acg.acgo my_acg.acg

This will produce a my_acg.acgo file (note that this is the default
name and location if the -o option is not provided).

Then, running :

$ acg

will open a prompt in which you can type:

# load o my_acg.acgo;

to load the data contained in the my_acg.acg file. Assuming you have
defined the signature Sig and the lexicon Lex, you can then run the
following commands:

# Sig check lambda x.some_cst x: NP ->S;

to check whether "lambda x.cst x" is a term of type "NP ->S" according
to Sig.

You can type:

# Lex realize lambda x.cst x: NP ->S;

to compute the image of "lambda x.cst x" is a term of type "NP ->S" by
Lex (assuming this term and this type are correct according to the
abstract signature of Lex).

You can type:

# Lex parse John+loves+Mary: S;

to check whether the term "John+loves+Mary" has an antecend of type
"S" by Lex, assuming that "John+loves+Mary" is a term of type "Lex
(S)" in the object signature of Lex.

Type CTRL-D to exit from the program.

********************
** ACG emacs mode **
********************

There is an ACG emacs mode (acg.el) in the emacs directory.

Look at the INSTALL file to see how to install it and where you can
find the acg.el file if automatically installed (in particular using
opam).

It's main feature is to be loaded when editing an acg data file (with
signatures and lexicons). It is automatically loaded for files with a
.acg extension

It basically contains compilation directives and next-error
searching.

1. First load an acg file

2. then run "M-x compile" (or C-cC-c) to call the compiler (acgc or
acgc.opt)

3. then run "M-x next-error" (or C-x`) to search for the next error
(if any) and highlights it



************************************
* Syntax of signature and lexicons *
************************************

(see the examples/tag.acg file for an example)

Signatures are defined by:

signature my_sig_name=
	sig_entries
end

Sig_entries always ends with a ; and can be:
+ type declaration as in
	NP,S : type;

+ type definition as in
	o :type;
	string = o -> o;

Note that type constructors are -> and => for the linear and
intuitionnistic arrow respectively.

+ constant declarations as in
	foo:NP;
	bar,dummy:NP -> S;
	infix + : string -> string -> string;
	prefix - : bool -> bool;
	binder All : (e =>t) -> t;
	infix > : bool -> bool -> bool; (*This means implication*)

Note that infix and prefix are keywords to introduce symbols (of
length 1. This probably will change).
Also notes that comments are surrounded by (* and *)

+ constant definitions as in
	n = lambda n. bar n : NP -> S;
	infix + = lambda x y z.x(y z): string -> string -> string;
	prefix - = lambda p.not p:bool -> bool;
	everyone = lambda P. All x. (human x) > (P x) ;

Note the syntax for binders (All in the last example). Available
construction for terms are:
	lambda x y z.t 
for linear abstraction

	Lambda x y z.t
for non-linear abstraction

	t u v
for application (eauql to (t u) v)

	t SYM u
if SYM is a infix symbol (lowest priority)

	SYM t
if SYM is a prefic symbol (highest priority)

	BINDER x y z.t
if BINDER is a binder

Lexicons are defined by:

lexicon my_lex_name(abstract_sig_name) : object_sig_name =
	lex_entries
end

or by lexicon composition as in:
lexicon my_new_lex = lex_2 << lex_1

Lex_entries always ends with a ; and have the following form:
	abstract_atomic_type1, abstract_atomic_type2 := object_type;
	abstract_const1, abstract_const2 := object_term;