[board] Cave to pressure and implement fmt::Display for Position

It prints a nice diagram!

Now I can make the position module private.

board/src/lib.rs

@@ -8,8 +8,7 @@ mod r#move;
 mod macros;
 mod move_generator;
 pub mod piece;
-#[macro_use]
-pub mod position;
+mod position;
 mod sight;
 mod square;
 

board/src/position/position.rs

@@ -4,10 +4,11 @@ use super::{flags::Flags, piece_sets::PieceBitBoards, Pieces};
 use crate::{
     move_generator::Moves,
     piece::{Color, Piece, PlacedPiece, Shape},
+    position::DiagramFormatter,
     sight::Sight,
     BitBoard, Move, Square,
 };
-use std::cell::OnceCell;
+use std::{cell::OnceCell, fmt};
 
 /// A lateral side of the board relative to the player. Kingside is the side the
 /// player's king starts on. Queenside is the side of the board the player's
@@ -211,6 +212,12 @@ impl Default for Position {
     }
 }
 
+impl fmt::Display for Position {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", DiagramFormatter::new(self))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::position;

explorer/src/main.rs

@@ -1,5 +1,4 @@
 use board::piece::{Color, Piece, Shape};
-use board::position::DiagramFormatter;
 use board::{Position, Square};
 use clap::{Arg, Command};
 use rustyline::error::ReadlineError;
@@ -80,8 +79,7 @@ fn main() -> Result<(), String> {
     let mut pos = Position::empty();
 
     loop {
-        let diagram = DiagramFormatter::new(&pos);
-        println!("{}", diagram);
+        println!("{}", &pos);
 
         let readline = editor.readline("? ");
         match readline {