cogent/examples/hello-world/main.ac

/*
 * Copyright 2017, NICTA
 *
 * This software may be distributed and modified according to the terms of
 * the GNU General Public License version 2. Note that NO WARRANTY is provided.
 * See "LICENSE_GPLv2.txt" for details.
 *
 * @TAG(NICTA_GPL)
 */

/*
 * The standard C headers need to be `escaped`, since Cogent's C parser
 * can not parse all of the C standard.
 */
$esc:(#include <stdio.h>)

/*
 * `SysState` is the 'world', everything outside the Cogent program
 * that is encapsulated into this variable. Essentially the state of
 * the external world.
 */
typedef void *SysState;

/*
 * `generated.c` is the C file that Cogent generates after parsing
 * the `HelloWorld.cogent` file (and any other cogent files that
 * is included in `HelloWorld.cogent`.
 */
#include "generated.c"

/*
 * For every included cogent file in cogent, there is either a corresponding
 * antiquoted C file(.ac file) in library or in our source repo, that contains
 * the implementations of all the abstract data types and functions.
 *
 * XXX | Since we included `common.cogent` in `HelloWorld.cogent` we include the
 * XXX | ac file here. Although, in our current program we don't use anything from
 * XXX | common.cogent (except SysState, which we've defined in the begining of
 * XXX | this file.
 *
 * REVISE: We don't include `common.ac` as it currently contains kernel-specific
 * implementations (like printk, etc.). If we exclude this .ac file, there will
 * be undefined C functions present in the final single .c file. As long as these
 * functions are not used anywhere, it is safe to do so (although there might be
 * warnings).
 */
//#include <gum/anti/common.ac>


/*
 * print_string
 */
$ty:(SysState) print_string($ty:((SysState, String)) arg)
{
        printf("%s\n", arg.p2);
        return arg.p1;
}

int main(void)
{
        $ty:(SysState) st;

        /* helloworld() is defined in HelloWorld.cogent */
        st = $exp:helloworld(st);

        return 0;
}