Function with_monomorphic_program_checked 

pub fn with_monomorphic_program_checked<T>(
    input: &str,
    options: Options,
    f: impl for<'a> FnOnce(Result<(&'a [Stmt<'a>], &'a TypeRegistry, PolicyRegistry), ParseError>, &'a Interner) -> Result<T, ParseError>,
) -> Result<T, ParseError>

with_parsed_program_checked over the program’s monomorphic form (crate::monomorphize) — every generic function and applied generic type made concrete — for a backend that lowers only concrete code.