Function with_monomorphic_program 

pub fn with_monomorphic_program<R>(
    input: &str,
    options: Options,
    f: impl for<'a> FnOnce(Result<(&'a [Stmt<'a>], &'a TypeRegistry, PolicyRegistry), String>, &'a Interner) -> R,
) -> R

with_parsed_program 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.