Basic PEG grammar for Stoffel Lang

[Mikerah]

I have a basic PEG grammar for StoffelLang along with some skeleton code for what the parser should do and to provide some more guidance of what the compiler's functionality should be. I haven't amended the honeybadgerswap examples as there is still some more thought that needs to go into the grammar.

Currently, the grammar doesn't support the following:

• imports: Ideally, this will be added once we have the standard library and a corresponding example
• maps: It's unclear whether maps should be included in the language as part of the grammar or the standard library or at all. Having keys be secret shared numbers would require the use of ORAM. As such, I have omitted this for the first version of the grammar.

[th4s]

Looks good to me. I haven't used pest before but it seems that this is exactly the right tool for developing a new language/grammar in Rust.

The pairs api seems to allow to iterate over the parsed tokens. I think this is where we will have to add our optimizations. After that we can start translating to VM bytecode.

[Mikerah]

I amended the HoneyBadgerSwap example to fit the current grammar. The last thing to add before converting this draft PR into an actual PR is some skeleton code for the parser.

[Mikerah]

I have a more complete grammar, have amended the honey badger swap example further and added some skeleton code for the parser. With Pest, a lot of the code is auto-generated, so all that is need is to define enums/structs and use the corresponding derive macros.