initial ast and parser structure skeleton

[edg-l]

The ast was inspired from our austral port.

The parser in this pr is just enough to parse the factorial program at the bottom.

Current test produces the following output:

Program:

mod ModuleName {
    const MY_CONSTANT: u8 = 2;
    const MY_CONSTANT2: bool = true;
    const MY_CONSTANT3: string = "hello world!";
}

Ast:

[crates/concrete_parser/src/lib.rs:26] ast = [
    ModuleBase {
        doc_string: None,
        imports: [],
        name: Ident {
            name: "ModuleName",
            span: Span {
                from: 5,
                to: 15,
            },
        },
        contents: [
            Constant(
                ConstantDef {
                    decl: ConstantDecl {
                        doc_string: None,
                        name: Ident {
                            name: "MY_CONSTANT",
                            span: Span {
                                from: 28,
                                to: 39,
                            },
                        },
                        type: Simple {
                            name: Ident {
                                name: "u8",
                                span: Span {
                                    from: 41,
                                    to: 43,
                                },
                            },
                        },
                    },
                    value: Atomic(
                        ConstInt(
                            2,
                        ),
                    ),
                },
            ),
            Constant(
                ConstantDef {
                    decl: ConstantDecl {
                        doc_string: None,
                        name: Ident {
                            name: "MY_CONSTANT2",
                            span: Span {
                                from: 59,
                                to: 71,
                            },
                        },
                        type: Simple {
                            name: Ident {
                                name: "bool",
                                span: Span {
                                    from: 73,
                                    to: 77,
                                },
                            },
                        },
                    },
                    value: Atomic(
                        ConstBool(
                            true,
                        ),
                    ),
                },
            ),
            Constant(
                ConstantDef {
                    decl: ConstantDecl {
                        doc_string: None,
                        name: Ident {
                            name: "MY_CONSTANT3",
                            span: Span {
                                from: 96,
                                to: 108,
                            },
                        },
                        type: Simple {
                            name: Ident {
                                name: "string",
                                span: Span {
                                    from: 110,
                                    to: 116,
                                },
                            },
                        },
                    },
                    value: Atomic(
                        ConstStr(
                            "\"hello world!\"",
                        ),
                    ),
                },
            ),
        ],
    },
]

factorial:

mod FactorialModule {
    pub fn factorial(x: u64) -> u64  {
        return match x {
            0 -> return 1,
            n -> return n * factorial(n-1),
        };
    }
}

https://gist.github.com/edg-l/068898bb319fdb324beca30b08c7caf4

[codecov-commenter]

Welcome to Codecov 🎉

Once merged to your default branch, Codecov will compare your coverage reports and display the results in this comment.

Thanks for integrating Codecov - We've got you covered ☂️

[juanbono]

LGTM

[unbalancedparentheses]

Shouldn't be commented

[unbalancedparentheses]

@igaray mentioned a few things were off, let's fix it in the next pr.