bug fixes and performance improvements

src/cli.rs

@@ -0,0 +1,19 @@
+use std::{fmt::Display, io::{stdin, BufRead, stdout, Write}};
+
+pub fn prompt<T: Display, E: Display>(
+  prompt: &str,
+  default: T,
+  mut try_cast: impl FnMut(String) -> Result<T, E>
+) -> T {
+  loop {
+    print!("{prompt} ({default}): ");
+    stdout().lock().flush().unwrap();
+    let mut input = String::with_capacity(100);
+    stdin().lock().read_line(&mut input).unwrap();
+    if input.len() == 0 {return default}
+    match try_cast(input) {
+      Ok(t) => return t,
+      Err(e) => println!("Error: {e}")
+    }
+  }
+}