aoc: stop printing inside run functions

This will make benching implementations easier

aoc/src/lib.rs

@@ -7,7 +7,7 @@ macro_rules! err {
     ($($string:expr),+) => (Box::<dyn std::error::Error>::from(format!($($string),+)))
 }
 
-type DayFunc = fn() -> Result<()>;
+pub type DayFunc = fn() -> Result<String>;
 
 pub fn run(days: &[DayFunc]) -> Result<()> {
     let mut args = env::args();
@@ -16,14 +16,16 @@ pub fn run(days: &[DayFunc]) -> Result<()> {
     match args.next() {
         Some(arg) => {
             let day: usize = arg.parse().expect("Please provide a day number");
-            days[day - 1]().unwrap_or_else(|e| eprintln!("error running day specified: {}", e));
+            let res =
+                days[day - 1]().or_else(|e| Err(err!("error running day specified: {}", e)))?;
+            println!("{}", res);
         }
         None => {
             for (i, day) in days.iter().enumerate() {
                 let i = i + 1;
                 println!("day{}: ", i);
-                day().unwrap_or_else(|e| eprintln!("error running day {}: {}", i, e));
-                println!();
+                let res = day().or_else(|e| Err(err!("error running day {}: {}", i, e)))?;
+                println!("{}", res);
             }
         }
     }