Currently semantic_parser::Env::get_bin_op_prec takes a &BinOp and returns a Result<&OpInfo, Error>. This requires the user of the function to allocate and clone uncessary variables for the argument &BinOp.

Suggestion: Optimize it with a trait with getters for the fields of BinOp instead, so the function takes any class that implements the trait.

The current syntax parser returns the first encountered error in each global item. So in each parse, it will only show the first encountered error for each global item, all the tokens in the same item after that are deteced as syntax_parser::Error::UnknownTokenInGlobalScope.

The error handling of syntax parser should be changed so that it tries not to stop the entire parsing of the global item due to one single error.

I haven't come up with any specific design to do this yet. But storing a Vec<Error> in each Expr may be a solution, similar to the semantic_parser, but the implementation would be different, as syntax_parser has to attempt to continue parsing by assuming the errror didn't occur.