# Floorplan compiler

A language for specifying the layout of a one-dimensional address space, particularly
for garbage collectors and manual memory managers written in Rust.

## Building and running

Floorplan is written in Haskell and must be [built with stack](https://docs.haskellstack.org/en/stable/README/).
Once you have stack installed on your system, you should be able to run the build
command and everything should just work:

```bash
$ stack build
...
Completed 2 action(s).
```

At which point you can compile the file `examples/immix/layout.flp` with
the `build-immix` script:

```bash
$ ./build-immix
...
   Compiling immix_rust v0.0.1 (/home/karl/w/flp/examples/immix)
   Finished dev [unoptimized + debuginfo] target(s) in 4.56s
```

This script ensures the Floorplan compiler is built, installs it for your current
user, and then builds the Immix project which itself invokes the Floorplan compiler
to build the file `examples/immix/src/heap/layout.flp`.

In order to run the compiler against some other `.flp` file, the compiler can
be run directly as follows:

```bash
stack exec flp [path/to/layout.flp] [path/to/generated.rs]
```

Note that in order to subsequently build a Rust file generated in this manner,
you must include the `flp-framework` to your Cargo dependencies, and `flp-compiler`
to your cargo build-dependencies. The later is simply a wrapper for calling out
to the (already stack-installed) flp compiler, and the framework crate contains
necessary macros and address types that generated Rust code uses.

The skeleton of a Rust cargo project is given in the `gen/` directory of this
repo, which can be copied over and modified to support the needs of a memory
manager other than immix-rust.

## Dependencies

A customized version of the [language-rust](https://github.com/harpocrates/language-rust)
package is included in the `deps/` directory of this repo, which adds support for
directly splicing of host language expressions into quasiquoted Rust code. This is the
mechanism by which Floorplan generates Rust code.

## Testing and contributing

If you want to help maintain or contribute new code to this project, feel free to
make a pull request or better yet start an issue in the the Issues tracker so that
you can get our feedback along the way. A number of avenues for work on the compiler
exist, including but not limited to:

- More example Rust allocators implemented with a Floorplan layout.
- Rust templates for allocating on alignment boundaries.
- Extensively document the interfaces generated.
- Better error messages.
- Integrating the core semantics (`app/semantics.hs`) directly into the project
  `src/` hierarchy.
- Calling out to a SMT library to verify alignment and size constraints.
- Targeting both C and Rust.
- Support for non-64-bit architectures.
- Generating debugging assertions.
- Dynamic tracking of type information for each piece of the heap.
- Cleaning up the dependencies by integrating the Rust splicing support directly
  into [the upstream repository](https://github.com/harpocrates/language-rust),
  e.g. as a separate quasiquoter.
- Generate cargo-based Rust documentation alongside generated functions, indicating
  why a certain function was generated and how it might be used.
- Repairing the Coq proofs in the `proofs/*.v` files.
- Better Rust integration and downstream crates.