AST to code generation

[kdziamura]

What

Currently, the formatter doesn't know how to format valid AST that lacks spaces

Example

This invalid code: ``` main = expect Bool.isEq 1 2 x ``` Was generated from this valid AST: ``` Defs { tags: [ Index(2147483648), ], regions: [ @0-31, ], space_before: [ Slice(start = 0, length = 0), ], space_after: [ Slice(start = 0, length = 0), ], spaces: [], type_defs: [], value_defs: [ Body( @0-4 Identifier { ident: "main", }, @11-31 Expect( @18-24 Apply( @20-22 Var { module_name: "Bool", ident: "isEq", }, [ @18-19 Num( "1", ), @23-24 Num( "2", ), ], BinOp( Equals, ), ), @29-31 Var { module_name: "", ident: "x", }, ), ), ], } ```

Why

• Using formatter in tests: the code from the example is from this snapshot
• Generating valid code from valid space-less AST might be good for possible {lang}-to-roc AST transformers

How

A possible workaround would be adding the opposite version of the trait RemoveSpaces, so that's possible to add spaces to AST where they're lacking.