Added Parser

[vkobinski]

Added a lot of Python AST Parsing to Bend Books.

[steinerkelvin]

Please add comments to non-obvious dependencies.

(We are always striving to have fewer dependencies, so it's good to have the non-obvious ones explained)

[vkobinski]

IndexMap is used by Bend to store their ADTs and constructor definitions, so I needed to add it to be able to construct a new IndexMap when parsing a new ADT.

[steinerkelvin]

A cast from f32 to F24 is an operation that could fail, so I imagine BendType::to_bend should actually return a Result akin to std::convert::TryInto.

Actually, the whole type BendType could be TryInto<Expr> if it's only method will be to_bend.

[vkobinski]

I was thinking about some other methods that could help a type implementation in Benda, I will change the return type to a Result for now.
The BendType is useful for Generics, I'm using it in:

benda/crates/benda/src/types/mod.rs

Lines 18 to 27 in 28e0bdd

	pub fn extract_inner<'py, T: BendType + PyTypeCheck + FromPyObject<'py>>(
	arg: Bound<'py, PyAny>,
	) -> Option<T> {
	let inner = arg.downcast::<T>();
	if let Ok(inner) = inner {
	let inner = <T as FromPyObject>::extract_bound(inner.as_any());
	return Some(inner.unwrap());
	}
	None
	}

[steinerkelvin]

Is this being used anywhere?

I don't think we should be relying on strings like this in the final version.
(if we can rely on in the identity of the types though the Python API and Python itself is not using strings)

[vkobinski]

I'll find a way to reference these types in a better way. I don't like this kind of String usage either.

[vkobinski]

The types names are not mapped anywhere in pyo3. I will find a better solution when our subset are better defined.
I use this From here:

benda/crates/benda/src/types/mod.rs

Line 48 in 28e0bdd

let arg_type = BuiltinType::from(name.to_string());