c2ats - generate ATS interface from C code

What's this?

ATS is a statically typed programming language that unifies implementation with formal specification. It can powerfully capture invariant in program.

However, don't you feel frustration to use API of many C language libraries from ATS code? Don't you manually import such API into ATS code?

The c2ats is an utility to generate ATS's sats file importing from C language header, semi-automatically.

Requirements

• GCC to parse C language header
• cabal or stack to build Haskell code

We are testing this tool on Debian GNU/Linux.

Install

Checkout source code of the c2ats:

$ git clone https://github.com/metasepi/c2ats.git
$ cd c2ats

Then install using cabal:

$ cabal install
$ which c2ats
/home/YourName/.cabal/bin/c2ats

or install using stack:

$ stack install
$ which c2ats
/home/YourName/.local/bin/c2ats

Usage

Start from Hello World example. Create following fake C language header to use printf(3) function in C language:

$ vi example.h
#include <stdio.h>

Next, let the c2ats to generate ATS sats file from above header:

$ c2ats gen example.h > example.sats
$ wc -l example.sats
318 example.sats
$ grep _printf example.sats
fun fun_c2ats_printf: {l1:addr} (!ptr_v_1(char, l1) | ptr l1) -> int = "mac#printf"

The sats file has many ATS declarations generated from the C header. It includes a declaration of printf(3) which can be used as following in dats:

$ vi main.dats
#include "share/atspre_define.hats"
#include "share/atspre_staload.hats"

staload UN = "prelude/SATS/unsafe.sats"

staload "example.sats"

fun my_printf (s: string): void = {
  val p = string2ptr s
  val (pfat, fpfat | p) = $UN.ptr_vtake p
  val ret = fun_c2ats_printf (pfat | p)
  prval () = fpfat pfat
}

implement main0 () = {
  val s = "Hello, world!\n"
  val () = my_printf s
}
$ patscc main.dats
$ ./a.out
Hello, world!

Of course, above code is so messy. It's caused by assigning a bad signature to fun_c2ats_printf function. You can get better dats code, if modify sats file as following:

$ vi example.sats
--snip--
fun fun_c2ats_printf: (string) -> int = "mac#printf"
--snip--
$ vi main.dats
#include "share/atspre_define.hats"
#include "share/atspre_staload.hats"

staload UN = "prelude/SATS/unsafe.sats"

staload "example.sats"

implement main0 () = {
  val s = "Hello, world!\n"
  val _ = fun_c2ats_printf s
}
$ patscc main.dats
$ ./a.out
Hello, world!

Totally, the c2ats generates a scaffold (you may be familiar with Ruby on Rails) to build ATS application. Sometimes, it's useful to create application rapidly. However, such scaffold should be replaced with better signature until shipping your product.

The other examples are found at example directory.

License

GPLv3 or later.