From 7e08a9adc44eba7ffc85e893b23cff66c81dba2f Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Tue, 23 Jan 2024 17:18:48 -0800
Subject: [PATCH 01/12] [core] Create a core crate

---
 Cargo.toml      | 1 +
 core/Cargo.toml | 8 ++++++++
 core/src/lib.rs | 0
 3 files changed, 9 insertions(+)
 create mode 100644 core/Cargo.toml
 create mode 100644 core/src/lib.rs

diff --git a/Cargo.toml b/Cargo.toml
index 655f6ac..d595fa5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,5 +2,6 @@
 
 members = [
     "board",
+    "core",
     "explorer",
 ]
diff --git a/core/Cargo.toml b/core/Cargo.toml
new file mode 100644
index 0000000..900733d
--- /dev/null
+++ b/core/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "core"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/core/src/lib.rs b/core/src/lib.rs
new file mode 100644
index 0000000..e69de29

From 406631b617646a43967668ae94125d94e62fcf2b Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:25:56 -0800
Subject: [PATCH 02/12] [core] Move the contents of board::square to
 core::coordinates

Export Square, Rank, and File from the core crate.
---
 board/src/lib.rs                              |   1 -
 .../src/square.rs => core/src/coordinates.rs  | 361 ++++++++++--------
 core/src/lib.rs                               |   3 +
 3 files changed, 212 insertions(+), 153 deletions(-)
 rename board/src/square.rs => core/src/coordinates.rs (55%)

diff --git a/board/src/lib.rs b/board/src/lib.rs
index 3db0753..8c68fad 100644
--- a/board/src/lib.rs
+++ b/board/src/lib.rs
@@ -12,7 +12,6 @@ mod move_generator;
 pub mod piece;
 mod position;
 mod sight;
-mod square;
 
 pub use piece::{Color, Piece};
 pub use position::{MoveBuilder as MakeMoveBuilder, Position, PositionBuilder};
diff --git a/board/src/square.rs b/core/src/coordinates.rs
similarity index 55%
rename from board/src/square.rs
rename to core/src/coordinates.rs
index 23565cf..fd0d25e 100644
--- a/board/src/square.rs
+++ b/core/src/coordinates.rs
@@ -1,8 +1,10 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::Color;
-use std::{fmt, str::FromStr};
+use std::fmt;
+use std::str::FromStr;
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[repr(u8)]
 pub enum Direction {
     North,
     NorthWest,
@@ -14,14 +16,24 @@ pub enum Direction {
     NorthEast,
 }
 
-#[derive(Debug)]
-pub struct ParseFileError;
+impl Direction {
+    pub fn to_offset(&self) -> i8 {
+        const OFFSETS: [i8; 8] = [8, 7, -1, -9, -8, -7, 1, 9];
+        OFFSETS[*self as usize]
+    }
+}
 
-#[derive(Debug)]
-pub struct ParseSquareError;
+macro_rules! try_from_integer {
+    ($type:ident, $int_type:ident) => {
+        impl TryFrom<$int_type> for $type {
+            type Error = ();
 
-#[derive(Debug)]
-pub struct SquareOutOfBoundsError;
+            fn try_from(value: $int_type) -> Result<Self, Self::Error> {
+                Square::try_from(value as u8)
+            }
+        }
+    };
+}
 
 macro_rules! coordinate_enum {
     ($name: ident, $($variant:ident),*) => {
@@ -34,43 +46,116 @@ macro_rules! coordinate_enum {
         impl $name {
             pub const NUM: usize = [$(Self::$variant), *].len();
             pub const ALL: [Self; Self::NUM] = [$(Self::$variant), *];
+        }
 
-            #[inline]
-            pub(crate) fn from_index(index: usize) -> Self {
-                assert!(
-                    index < Self::NUM,
-                    "Index {} out of bounds for {}.",
-                    index,
-                    stringify!($name)
-                );
-                Self::try_index(index).unwrap()
+        impl TryFrom<u8> for $name {
+            type Error = ();
+
+            fn try_from(value: u8) -> Result<Self, Self::Error> {
+                let value_usize = value as usize;
+                if value_usize < Self::NUM {
+                    Ok($name::ALL[value_usize])
+                } else {
+                    Err(())
+                }
+            }
+        }
+
+        try_from_integer!($name, u16);
+        try_from_integer!($name, u32);
+        try_from_integer!($name, u64);
+    }
+}
+
+macro_rules! range_bound_struct {
+    ($vis:vis, $type:ident, $repr:ty, $max:expr) => {
+        #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
+        $vis struct $type($repr);
+
+        #[allow(dead_code)]
+        impl $type {
+            $vis const FIRST: $type = $type(0);
+            $vis const LAST: $type = $type($max - 1);
+        }
+
+        impl $type {
+            $vis fn new(x: $repr) -> Option<Self> {
+                if x < $max {
+                    Some(Self(x))
+                } else {
+                    None
+                }
             }
 
-            pub fn try_index(index: usize) -> Option<Self> {
-                $(
-                    #[allow(non_upper_case_globals)]
-                    const $variant: usize = $name::$variant as usize;
-                )*
+            $vis unsafe fn new_unchecked(x: $repr) -> Self {
+                Self(x)
+            }
+        }
 
-                #[allow(non_upper_case_globals)]
-                match index {
-                    $($variant => Some($name::$variant),)*
-                    _ => None,
-                }
+        impl Into<$repr> for $type {
+            fn into(self) -> $repr {
+                self.0
+            }
+        }
+
+        impl TryFrom<$repr> for $type {
+            type Error = ();
+
+            fn try_from(value: $repr) -> Result<Self, Self::Error> {
+                Self::new(value).ok_or(())
             }
         }
     }
 }
 
-#[rustfmt::skip]
-coordinate_enum!(Rank,
-    One, Two, Three, Four, Five, Six, Seven, Eight
-);
+range_bound_struct!(pub, File, u8, 8);
 
-#[rustfmt::skip]
-coordinate_enum!(File,
-    A, B, C, D, E, F, G, H
-);
+impl File {
+    pub const A: File = File(0);
+    pub const B: File = File(1);
+    pub const C: File = File(2);
+    pub const D: File = File(3);
+    pub const E: File = File(4);
+    pub const F: File = File(5);
+    pub const G: File = File(6);
+    pub const H: File = File(7);
+
+    pub const ALL: [File; 8] = [
+        File::A,
+        File::B,
+        File::C,
+        File::D,
+        File::E,
+        File::F,
+        File::G,
+        File::H,
+    ];
+}
+
+range_bound_struct!(pub, Rank, u8, 8);
+
+#[allow(dead_code)]
+impl Rank {
+    pub const ONE: Rank = Rank(0);
+    pub const TWO: Rank = Rank(1);
+    pub const THREE: Rank = Rank(2);
+    pub const FOUR: Rank = Rank(3);
+    pub const FIVE: Rank = Rank(4);
+    pub const SIX: Rank = Rank(5);
+    pub const SEVEN: Rank = Rank(6);
+    pub const EIGHT: Rank = Rank(7);
+
+    pub const ALL: [Rank; 8] = [
+        Rank::ONE,
+        Rank::TWO,
+        Rank::THREE,
+        Rank::FOUR,
+        Rank::FIVE,
+        Rank::SIX,
+        Rank::SEVEN,
+        Rank::EIGHT,
+    ];
+}
 
 #[rustfmt::skip]
 coordinate_enum!(Square,
@@ -84,138 +169,87 @@ coordinate_enum!(Square,
     A8, B8, C8, D8, E8, F8, G8, H8
 );
 
-impl Into<char> for File {
-    fn into(self) -> char {
-        ('a' as u8 + self as u8) as char
-    }
-}
-
-impl TryFrom<char> for File {
-    type Error = ParseFileError;
-
-    fn try_from(value: char) -> Result<Self, Self::Error> {
-        let lowercase_value = value.to_ascii_lowercase();
-        for file in File::ALL.iter() {
-            if lowercase_value == (*file).into() {
-                return Ok(*file);
-            }
-        }
-
-        Err(ParseFileError)
-    }
-}
-
-impl fmt::Display for File {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", Into::<char>::into(*self).to_uppercase())
-    }
-}
-
-impl Into<char> for Rank {
-    fn into(self) -> char {
-        ('1' as u8 + self as u8) as char
-    }
-}
-
-impl TryFrom<char> for Rank {
-    type Error = ParseFileError;
-
-    fn try_from(value: char) -> Result<Self, Self::Error> {
-        let lowercase_value = value.to_ascii_lowercase();
-        for rank in Self::ALL.iter().cloned() {
-            if lowercase_value == rank.into() {
-                return Ok(rank);
-            }
-        }
-
-        Err(ParseFileError)
-    }
-}
-
-impl fmt::Display for Rank {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", Into::<char>::into(*self))
-    }
-}
-
 impl Square {
+    pub unsafe fn from_index(x: u8) -> Square {
+        Self::try_from(x).unwrap_unchecked()
+    }
+
     #[inline]
     pub fn from_file_rank(file: File, rank: Rank) -> Square {
-        Self::from_index((rank as usize) << 3 | file as usize)
-    }
-
-    #[inline]
-    pub fn file(self) -> File {
-        File::from_index(self as usize & 0b000111)
-    }
-
-    #[inline]
-    pub fn rank(self) -> Rank {
-        Rank::from_index(self as usize >> 3)
-    }
-}
-
-impl Square {
-    const KING_STARTING_SQUARES: [Square; 2] = [Square::E1, Square::E8];
-
-    pub fn king_starting_square(color: Color) -> Square {
-        Square::KING_STARTING_SQUARES[color as usize]
+        let file_int: u8 = file.into();
+        let rank_int: u8 = rank.into();
+        unsafe { Self::from_index(rank_int << 3 | file_int) }
     }
 
     pub fn from_algebraic_str(s: &str) -> Result<Square, ParseSquareError> {
         s.parse()
     }
 
+    #[inline]
+    pub fn file(self) -> File {
+        unsafe { File::new_unchecked((self as u8) & 0b000111) }
+    }
+
+    #[inline]
+    pub fn rank(self) -> Rank {
+        unsafe { Rank::new_unchecked((self as u8) >> 3) }
+    }
+
     pub fn neighbor(self, direction: Direction) -> Option<Square> {
+        let index: u8 = self as u8;
+        let dir: i8 = direction.to_offset();
         match direction {
-            Direction::North => Square::try_index(self as usize + 8),
+            Direction::North => Square::try_from(index.wrapping_add_signed(dir)).ok(),
             Direction::NorthWest => {
-                if self.rank() != Rank::Eight {
-                    Square::try_index(self as usize + 7)
+                if self.rank() != Rank::EIGHT {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
             Direction::West => {
                 if self.file() != File::A {
-                    Square::try_index(self as usize - 1)
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
             Direction::SouthWest => {
-                if self.rank() != Rank::One {
-                    Square::try_index(self as usize - 9)
+                if self.rank() != Rank::ONE {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
             Direction::South => {
-                if self.rank() != Rank::One {
-                    Square::try_index(self as usize - 8)
+                if self.rank() != Rank::ONE {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
             Direction::SouthEast => {
-                if self.rank() != Rank::One {
-                    Square::try_index(self as usize - 7)
+                if self.rank() != Rank::ONE {
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
             Direction::East => {
                 if self.file() != File::H {
-                    Square::try_index(self as usize + 1)
+                    Square::try_from(index.wrapping_add_signed(dir)).ok()
                 } else {
                     None
                 }
             }
-            Direction::NorthEast => Square::try_index(self as usize + 9),
+            Direction::NorthEast => Square::try_from(index.wrapping_add_signed(dir)).ok(),
         }
     }
 }
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct ParseSquareError;
+
 impl FromStr for Square {
     type Err = ParseSquareError;
 
@@ -240,31 +274,54 @@ impl FromStr for Square {
     }
 }
 
-macro_rules! try_from_integer {
-    ($int_type:ident) => {
-        impl TryFrom<$int_type> for Square {
-            type Error = SquareOutOfBoundsError;
-
-            fn try_from(value: $int_type) -> Result<Self, Self::Error> {
-                Square::try_index(value as usize).ok_or(SquareOutOfBoundsError)
-            }
-        }
-    };
+impl fmt::Display for File {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", Into::<char>::into(*self))
+    }
 }
 
-try_from_integer!(u8);
-try_from_integer!(u16);
-try_from_integer!(u32);
-try_from_integer!(u64);
+impl fmt::Display for Rank {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", Into::<char>::into(*self))
+    }
+}
 
 impl fmt::Display for Square {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "{}{}",
-            ('a' as u8 + self.file() as u8) as char,
-            self.rank() as usize + 1
-        )
+        self.file().fmt(f)?;
+        self.rank().fmt(f)?;
+        Ok(())
+    }
+}
+
+impl Into<char> for File {
+    fn into(self) -> char {
+        let value: u8 = self.into();
+        (value + 'a' as u8) as char
+    }
+}
+
+impl Into<char> for Rank {
+    fn into(self) -> char {
+        let value: u8 = self.into();
+        (value + '1' as u8) as char
+    }
+}
+
+impl TryFrom<char> for File {
+    type Error = ();
+
+    fn try_from(value: char) -> Result<Self, Self::Error> {
+        File::try_from(value.to_ascii_lowercase() as u8 - 'a' as u8)
+    }
+}
+
+impl TryFrom<char> for Rank {
+    type Error = ();
+
+    fn try_from(value: char) -> Result<Self, Self::Error> {
+        let result = (value as u8).checked_sub('1' as u8).ok_or(())?;
+        Self::try_from(result)
     }
 }
 
@@ -275,16 +332,16 @@ mod tests {
     #[test]
     fn good_algebraic_input() {
         let sq = Square::from_algebraic_str("a4").expect("Failed to parse 'a4' square");
-        assert_eq!(sq.file(), File::A);
-        assert_eq!(sq.rank(), Rank::Four);
+        assert_eq!(sq.file(), File(0));
+        assert_eq!(sq.rank(), Rank(3));
 
         let sq = Square::from_algebraic_str("B8").expect("Failed to parse 'B8' square");
-        assert_eq!(sq.file(), File::B);
-        assert_eq!(sq.rank(), Rank::Eight);
+        assert_eq!(sq.file(), File(1));
+        assert_eq!(sq.rank(), Rank(7));
 
         let sq = Square::from_algebraic_str("e4").expect("Failed to parse 'B8' square");
-        assert_eq!(sq.file(), File::E);
-        assert_eq!(sq.rank(), Rank::Four);
+        assert_eq!(sq.file(), File(4));
+        assert_eq!(sq.rank(), Rank(3));
     }
 
     #[test]
@@ -299,13 +356,13 @@ mod tests {
 
     #[test]
     fn from_index() {
-        let sq = Square::try_index(4).expect("Unable to get Square from index");
-        assert_eq!(sq.file(), File::E);
-        assert_eq!(sq.rank(), Rank::One);
+        let sq = Square::try_from(4u32).expect("Unable to get Square from index");
+        assert_eq!(sq.file(), File(4));
+        assert_eq!(sq.rank(), Rank(0));
 
-        let sq = Square::try_index(28).expect("Unable to get Square from index");
-        assert_eq!(sq.file(), File::E);
-        assert_eq!(sq.rank(), Rank::Four);
+        let sq = Square::try_from(28u32).expect("Unable to get Square from index");
+        assert_eq!(sq.file(), File(4));
+        assert_eq!(sq.rank(), Rank(3));
     }
 
     #[test]
diff --git a/core/src/lib.rs b/core/src/lib.rs
index e69de29..2fe191d 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -0,0 +1,3 @@
+mod coordinates;
+
+pub use coordinates::{Direction, File, Rank, Square};

From 3c3a62345d2ec67983a01bdff6867fc702d9b37b Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:29:16 -0800
Subject: [PATCH 03/12] =?UTF-8?q?[core]=20Rename=20core=20=E2=86=92=20ches?=
 =?UTF-8?q?s=5Fcore?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Cargo.toml                              | 2 +-
 {core => chess_core}/Cargo.toml         | 2 +-
 {core => chess_core}/src/coordinates.rs | 0
 {core => chess_core}/src/lib.rs         | 0
 4 files changed, 2 insertions(+), 2 deletions(-)
 rename {core => chess_core}/Cargo.toml (88%)
 rename {core => chess_core}/src/coordinates.rs (100%)
 rename {core => chess_core}/src/lib.rs (100%)

diff --git a/Cargo.toml b/Cargo.toml
index d595fa5..0ecbba5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,6 +2,6 @@
 
 members = [
     "board",
-    "core",
+    "chess_core",
     "explorer",
 ]
diff --git a/core/Cargo.toml b/chess_core/Cargo.toml
similarity index 88%
rename from core/Cargo.toml
rename to chess_core/Cargo.toml
index 900733d..9b8c272 100644
--- a/core/Cargo.toml
+++ b/chess_core/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "core"
+name = "chess_core"
 version = "0.1.0"
 edition = "2021"
 
diff --git a/core/src/coordinates.rs b/chess_core/src/coordinates.rs
similarity index 100%
rename from core/src/coordinates.rs
rename to chess_core/src/coordinates.rs
diff --git a/core/src/lib.rs b/chess_core/src/lib.rs
similarity index 100%
rename from core/src/lib.rs
rename to chess_core/src/lib.rs

From 106800bcb353f57d6ceaf9f816d7ce96026dbd55 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:32:09 -0800
Subject: [PATCH 04/12] [core,board] Update all use imports referring to
 Square, Rank, and File

---
 board/Cargo.toml                              |  1 +
 board/src/fen.rs                              |  5 ++--
 board/src/lib.rs                              |  1 -
 board/src/macros.rs                           |  2 +-
 board/src/move.rs                             | 24 +++++++++----------
 board/src/move_generator/bishop.rs            |  2 +-
 board/src/move_generator/queen.rs             |  2 +-
 board/src/move_generator/rook.rs              |  7 +++---
 board/src/piece.rs                            |  6 ++---
 board/src/position/builders/move_builder.rs   |  4 ++--
 .../src/position/builders/position_builder.rs |  6 ++---
 board/src/position/diagram_formatter.rs       |  3 ++-
 board/src/position/piece_sets.rs              |  3 ++-
 board/src/position/pieces.rs                  |  3 +--
 board/src/position/position.rs                |  6 +++--
 board/src/sight.rs                            |  5 ++--
 16 files changed, 40 insertions(+), 40 deletions(-)

diff --git a/board/Cargo.toml b/board/Cargo.toml
index 6b600a9..da7df3c 100644
--- a/board/Cargo.toml
+++ b/board/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+chess_core = { path = "../chess_core" }
diff --git a/board/src/fen.rs b/board/src/fen.rs
index b212c94..be63610 100644
--- a/board/src/fen.rs
+++ b/board/src/fen.rs
@@ -3,8 +3,9 @@
 use crate::{
     piece::{Piece, PlacedPiece},
     r#move::Castle,
-    Color, File, Position, Rank, Square,
+    Color, Position,
 };
+use chess_core::{File, Rank, Square};
 use std::fmt::Write;
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
@@ -42,7 +43,7 @@ impl ToFen for Position {
                 write!(fen_string, "{}", empty_squares).map_err(|err| FenError::FmtError(err))?;
                 empty_squares = 0;
             }
-            if rank != &Rank::One {
+            if rank != &Rank::ONE {
                 write!(fen_string, "/").map_err(|err| FenError::FmtError(err))?;
             }
         }
diff --git a/board/src/lib.rs b/board/src/lib.rs
index 8c68fad..670368f 100644
--- a/board/src/lib.rs
+++ b/board/src/lib.rs
@@ -16,6 +16,5 @@ mod sight;
 pub use piece::{Color, Piece};
 pub use position::{MoveBuilder as MakeMoveBuilder, Position, PositionBuilder};
 pub use r#move::{Castle, MakeMoveError, Move, MoveBuilder};
-pub use square::{File, Rank, Square};
 
 pub(crate) use bitboard::BitBoard;
diff --git a/board/src/macros.rs b/board/src/macros.rs
index 9dd3323..ad69496 100644
--- a/board/src/macros.rs
+++ b/board/src/macros.rs
@@ -6,7 +6,7 @@ macro_rules! piece {
         $crate::piece::Piece::new($crate::piece::Color::$color, $crate::piece::Shape::$shape)
     };
     ($color:ident $shape:ident on $square:ident) => {
-        $crate::piece::PlacedPiece::new(piece!($color $shape), $crate::square::Square::$square)
+        $crate::piece::PlacedPiece::new(piece!($color $shape), chess_core::Square::$square)
     }
 }
 
diff --git a/board/src/move.rs b/board/src/move.rs
index 08cf988..c593b56 100644
--- a/board/src/move.rs
+++ b/board/src/move.rs
@@ -1,10 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{
-    piece::{Piece, PlacedPiece, Shape},
-    square::Rank,
-    Square,
-};
+use crate::piece::{Piece, PlacedPiece, Shape};
+use chess_core::{Rank, Square};
 use std::fmt;
 
 pub use castle::Castle;
@@ -20,7 +17,8 @@ pub enum MakeMoveError {
 }
 
 mod castle {
-    use crate::{Color, Square};
+    use crate::Color;
+    use chess_core::Square;
 
     #[repr(u16)]
     #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -248,8 +246,8 @@ impl MoveBuilder {
             Shape::Pawn => {
                 let from_rank = from.rank();
                 let to_rank = to.rank();
-                let is_white_double_push = from_rank == Rank::Two && to_rank == Rank::Four;
-                let is_black_double_push = from_rank == Rank::Seven && to_rank == Rank::Five;
+                let is_white_double_push = from_rank == Rank::TWO && to_rank == Rank::FOUR;
+                let is_black_double_push = from_rank == Rank::SEVEN && to_rank == Rank::FIVE;
                 if is_white_double_push || is_black_double_push {
                     Kind::DoublePush
                 } else {
@@ -421,8 +419,8 @@ mod move_formatter {
                         $crate::piece::Color::$color,
                         $crate::piece::Shape::$shape,
                     ),
-                    $crate::Square::$from_square,
-                    $crate::Square::$to_square,
+                    chess_core::Square::$from_square,
+                    chess_core::Square::$to_square,
                 )
                 .build()
             };
@@ -432,15 +430,15 @@ mod move_formatter {
                         $crate::piece::Color::$color,
                         $crate::piece::Shape::$shape,
                     ),
-                    $crate::Square::$from_square,
-                    $crate::Square::$to_square,
+                    chess_core::Square::$from_square,
+                    chess_core::Square::$to_square,
                 )
                 .capturing($crate::piece::PlacedPiece::new(
                     $crate::piece::Piece::new(
                         $crate::piece::Color::$captured_color,
                         $crate::piece::Shape::$captured_shape,
                     ),
-                    $crate::Square::$to_square,
+                    chess_core::Square::$to_square,
                 ))
                 .build()
             };
diff --git a/board/src/move_generator/bishop.rs b/board/src/move_generator/bishop.rs
index 7b07d54..7bad274 100644
--- a/board/src/move_generator/bishop.rs
+++ b/board/src/move_generator/bishop.rs
@@ -3,9 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    square::Direction,
     BitBoard, MoveBuilder, Position,
 };
+use chess_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
diff --git a/board/src/move_generator/queen.rs b/board/src/move_generator/queen.rs
index 6694bf6..10ad498 100644
--- a/board/src/move_generator/queen.rs
+++ b/board/src/move_generator/queen.rs
@@ -3,9 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    square::Direction,
     BitBoard, MoveBuilder, Position,
 };
+use chess_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
diff --git a/board/src/move_generator/rook.rs b/board/src/move_generator/rook.rs
index bd48711..8ee6acd 100644
--- a/board/src/move_generator/rook.rs
+++ b/board/src/move_generator/rook.rs
@@ -3,9 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    square::Direction,
     BitBoard, MoveBuilder, Position,
 };
+use chess_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
@@ -62,9 +62,8 @@ impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{
-        piece::Piece, position, position::DiagramFormatter, BitBoard, Color, Position, Square,
-    };
+    use crate::{piece::Piece, position, position::DiagramFormatter, BitBoard, Color, Position};
+    use chess_core::Square;
 
     #[test]
     fn classical_single_rook_bitboard() {
diff --git a/board/src/piece.rs b/board/src/piece.rs
index f65a7b8..cc91765 100644
--- a/board/src/piece.rs
+++ b/board/src/piece.rs
@@ -1,9 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{
-    display::{ASCIIDisplay, FENDisplay, UnicodeDisplay},
-    Square,
-};
+use crate::display::{ASCIIDisplay, FENDisplay, UnicodeDisplay};
+use chess_core::Square;
 use std::fmt;
 use std::slice::Iter;
 
diff --git a/board/src/position/builders/move_builder.rs b/board/src/position/builders/move_builder.rs
index 5d12b19..2146e9d 100644
--- a/board/src/position/builders/move_builder.rs
+++ b/board/src/position/builders/move_builder.rs
@@ -4,9 +4,9 @@ use crate::{
     piece::{PlacedPiece, Shape},
     position::flags::Flags,
     r#move::Castle,
-    square::Direction,
-    BitBoard, Color, MakeMoveError, Move, Piece, Position, Square,
+    BitBoard, Color, MakeMoveError, Move, Piece, Position,
 };
+use chess_core::{Direction, Square};
 
 /// A position builder that builds a new position by making a move.
 #[derive(Clone)]
diff --git a/board/src/position/builders/position_builder.rs b/board/src/position/builders/position_builder.rs
index 7c68413..0410ca3 100644
--- a/board/src/position/builders/position_builder.rs
+++ b/board/src/position/builders/position_builder.rs
@@ -5,9 +5,9 @@ use crate::{
     piece::{PlacedPiece, Shape},
     position::{flags::Flags, piece_sets::PieceBitBoards},
     r#move::Castle,
-    square::{Direction, Rank},
-    BitBoard, Color, MakeMoveError, Move, Piece, Position, Square,
+    BitBoard, Color, MakeMoveError, Move, Piece, Position,
 };
+use chess_core::{Rank, Square};
 use std::collections::BTreeMap;
 
 #[derive(Clone)]
@@ -100,7 +100,7 @@ impl Builder {
             // Pawns cannot be placed on the first (back) rank of their side,
             // and cannot be placed on the final rank without a promotion.
             let rank = piece.square().rank();
-            return rank != Rank::One && rank != Rank::Eight;
+            return rank != Rank::ONE && rank != Rank::EIGHT;
         }
 
         true
diff --git a/board/src/position/diagram_formatter.rs b/board/src/position/diagram_formatter.rs
index b007d20..ff4c3cf 100644
--- a/board/src/position/diagram_formatter.rs
+++ b/board/src/position/diagram_formatter.rs
@@ -1,6 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{File, Position, Rank, Square};
+use crate::Position;
+use chess_core::{File, Rank, Square};
 use std::fmt;
 
 pub struct DiagramFormatter<'a>(&'a Position);
diff --git a/board/src/position/piece_sets.rs b/board/src/position/piece_sets.rs
index 58921b9..fa08c84 100644
--- a/board/src/position/piece_sets.rs
+++ b/board/src/position/piece_sets.rs
@@ -2,8 +2,9 @@
 
 use crate::{
     piece::{Piece, PlacedPiece},
-    BitBoard, Color, Square,
+    BitBoard, Color,
 };
+use chess_core::Square;
 
 #[derive(Debug, Eq, PartialEq)]
 pub enum PlacePieceStrategy {
diff --git a/board/src/position/pieces.rs b/board/src/position/pieces.rs
index d1cb6c7..4e4495d 100644
--- a/board/src/position/pieces.rs
+++ b/board/src/position/pieces.rs
@@ -3,7 +3,7 @@
 use super::Position;
 use crate::piece::{Color, Piece, PlacedPiece, Shape};
 use crate::BitBoard;
-use crate::Square;
+use chess_core::Square;
 
 pub struct Pieces<'a> {
     color: Color,
@@ -76,7 +76,6 @@ impl<'a> Iterator for Pieces<'a> {
 mod tests {
     use super::*;
     use crate::piece::{Color, Piece, Shape};
-    use crate::Square;
     use crate::{Position, PositionBuilder};
     use std::collections::HashSet;
 
diff --git a/board/src/position/position.rs b/board/src/position/position.rs
index 484293e..ebc2948 100644
--- a/board/src/position/position.rs
+++ b/board/src/position/position.rs
@@ -7,8 +7,9 @@ use crate::{
     position::DiagramFormatter,
     r#move::Castle,
     sight::Sight,
-    BitBoard, Move, Square,
+    BitBoard, Move,
 };
+use chess_core::Square;
 use std::{cell::OnceCell, fmt};
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -266,7 +267,8 @@ impl fmt::Display for Position {
 
 #[cfg(test)]
 mod tests {
-    use crate::{position, Castle, Color, Position, Square};
+    use crate::{position, Castle, Color, Position};
+    use chess_core::Square;
 
     #[test]
     fn piece_on_square() {
diff --git a/board/src/sight.rs b/board/src/sight.rs
index 33bd2d8..7763bac 100644
--- a/board/src/sight.rs
+++ b/board/src/sight.rs
@@ -2,9 +2,9 @@
 
 use crate::{
     piece::{Color, PlacedPiece, Shape},
-    square::Direction,
     BitBoard, Position,
 };
+use chess_core::Direction;
 
 pub(crate) trait Sight {
     fn sight_in_position(&self, position: &Position) -> BitBoard;
@@ -174,7 +174,8 @@ mod tests {
     }
 
     mod pawn {
-        use crate::{sight::Sight, BitBoard, Square};
+        use crate::{sight::Sight, BitBoard};
+        use chess_core::Square;
 
         sight_test!(e4_pawn, piece!(White Pawn on E4), bitboard!(D5, F5));
 

From eab30cc33baea919991450a5a3d16c65b6731091 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:33:07 -0800
Subject: [PATCH 05/12] =?UTF-8?q?[core]=20Rename=20the=20directory=20chess?=
 =?UTF-8?q?=5Fcore=20=E2=86=92=20core?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

I think this is sufficient.
---
 {chess_core => core}/Cargo.toml         | 0
 {chess_core => core}/src/coordinates.rs | 0
 {chess_core => core}/src/lib.rs         | 0
 3 files changed, 0 insertions(+), 0 deletions(-)
 rename {chess_core => core}/Cargo.toml (100%)
 rename {chess_core => core}/src/coordinates.rs (100%)
 rename {chess_core => core}/src/lib.rs (100%)

diff --git a/chess_core/Cargo.toml b/core/Cargo.toml
similarity index 100%
rename from chess_core/Cargo.toml
rename to core/Cargo.toml
diff --git a/chess_core/src/coordinates.rs b/core/src/coordinates.rs
similarity index 100%
rename from chess_core/src/coordinates.rs
rename to core/src/coordinates.rs
diff --git a/chess_core/src/lib.rs b/core/src/lib.rs
similarity index 100%
rename from chess_core/src/lib.rs
rename to core/src/lib.rs

From 32100b9553169c8553bfa360221f7fe4845fcb0b Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:34:23 -0800
Subject: [PATCH 06/12] [bitboard] Make an empty chess_bitboard crate

This crate lives in bitboard/
---
 Cargo.toml          | 1 +
 bitboard/Cargo.toml | 9 +++++++++
 bitboard/src/lib.rs | 1 +
 3 files changed, 11 insertions(+)
 create mode 100644 bitboard/Cargo.toml
 create mode 100644 bitboard/src/lib.rs

diff --git a/Cargo.toml b/Cargo.toml
index 0ecbba5..a5661d8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,6 +2,7 @@
 
 members = [
     "board",
+    "chess_bitboard",
     "chess_core",
     "explorer",
 ]
diff --git a/bitboard/Cargo.toml b/bitboard/Cargo.toml
new file mode 100644
index 0000000..0670e94
--- /dev/null
+++ b/bitboard/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "chess_bitboard"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+core = { path = "../core" }
diff --git a/bitboard/src/lib.rs b/bitboard/src/lib.rs
new file mode 100644
index 0000000..8aa971d
--- /dev/null
+++ b/bitboard/src/lib.rs
@@ -0,0 +1 @@
+// Eryn Wells <eryn@erynwells.me>

From 625bfb2446de4e3a7502714523e82fe6b224fd85 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:35:22 -0800
Subject: [PATCH 07/12] [bitboard] Move everything in board::bitboard to the
 bitboard crate

---
 .../bitboard => bitboard/src}/bit_scanner.rs    |  0
 .../src/bitboard => bitboard/src}/bitboard.rs   | 13 +++++++------
 bitboard/src/lib.rs                             | 17 +++++++++++++++++
 {board/src/bitboard => bitboard/src}/library.rs |  2 +-
 {board/src/bitboard => bitboard/src}/shifts.rs  |  0
 board/src/bitboard/mod.rs                       | 16 ----------------
 board/src/lib.rs                                |  2 --
 7 files changed, 25 insertions(+), 25 deletions(-)
 rename {board/src/bitboard => bitboard/src}/bit_scanner.rs (100%)
 rename {board/src/bitboard => bitboard/src}/bitboard.rs (96%)
 rename {board/src/bitboard => bitboard/src}/library.rs (99%)
 rename {board/src/bitboard => bitboard/src}/shifts.rs (100%)
 delete mode 100644 board/src/bitboard/mod.rs

diff --git a/board/src/bitboard/bit_scanner.rs b/bitboard/src/bit_scanner.rs
similarity index 100%
rename from board/src/bitboard/bit_scanner.rs
rename to bitboard/src/bit_scanner.rs
diff --git a/board/src/bitboard/bitboard.rs b/bitboard/src/bitboard.rs
similarity index 96%
rename from board/src/bitboard/bitboard.rs
rename to bitboard/src/bitboard.rs
index 5c35ca8..730c7c2 100644
--- a/board/src/bitboard/bitboard.rs
+++ b/bitboard/src/bitboard.rs
@@ -1,8 +1,8 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use super::library::{library, FILES, RANKS};
-use super::LeadingBitScanner;
-use crate::{square::Direction, Square};
+use crate::library::{library, FILES, RANKS};
+use crate::LeadingBitScanner;
+use chess_core::{Direction, Square};
 use std::fmt;
 use std::ops::Not;
 
@@ -72,13 +72,13 @@ impl BitBoard {
     /// Return an Iterator over the occupied squares, starting from the leading
     /// (most-significant bit) end of the field.
     pub(crate) fn occupied_squares(&self) -> impl Iterator<Item = Square> {
-        LeadingBitScanner::new(self.0).map(Square::from_index)
+        LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
     }
 
     /// Return an Iterator over the occupied squares, starting from the trailing
     /// (least-significant bit) end of the field.
     pub(crate) fn occupied_squares_trailing(&self) -> impl Iterator<Item = Square> {
-        LeadingBitScanner::new(self.0).map(Square::from_index)
+        LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
     }
 }
 
@@ -243,7 +243,8 @@ impl BitBoardBuilder {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{bitboard, Square};
+    use crate::bitboard;
+    use chess_core::Square;
 
     #[test]
     fn display_and_debug() {
diff --git a/bitboard/src/lib.rs b/bitboard/src/lib.rs
index 8aa971d..d3c0c4b 100644
--- a/bitboard/src/lib.rs
+++ b/bitboard/src/lib.rs
@@ -1 +1,18 @@
 // Eryn Wells <eryn@erynwells.me>
+
+mod bit_scanner;
+mod bitboard;
+mod library;
+mod shifts;
+
+pub(crate) use bit_scanner::{LeadingBitScanner, TrailingBitScanner};
+pub(crate) use bitboard::{BitBoard, BitBoardBuilder};
+
+#[macro_export]
+macro_rules! bitboard {
+    ($($sq:ident),* $(,)?) => {
+        $crate::bitboard::BitBoardBuilder::empty()
+            $(.square(chess_core::Square::$sq))*
+            .build()
+    };
+}
diff --git a/board/src/bitboard/library.rs b/bitboard/src/library.rs
similarity index 99%
rename from board/src/bitboard/library.rs
rename to bitboard/src/library.rs
index fe2daa0..1e6a84d 100644
--- a/board/src/bitboard/library.rs
+++ b/bitboard/src/library.rs
@@ -1,7 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use super::BitBoard;
-use crate::{square::Direction, Square};
+use chess_core::{Direction, Square};
 use std::sync::Once;
 
 pub(super) const RANKS: [BitBoard; 8] = [
diff --git a/board/src/bitboard/shifts.rs b/bitboard/src/shifts.rs
similarity index 100%
rename from board/src/bitboard/shifts.rs
rename to bitboard/src/shifts.rs
diff --git a/board/src/bitboard/mod.rs b/board/src/bitboard/mod.rs
deleted file mode 100644
index c417abd..0000000
--- a/board/src/bitboard/mod.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-mod bit_scanner;
-mod bitboard;
-mod library;
-mod shifts;
-
-pub(crate) use bit_scanner::{LeadingBitScanner, TrailingBitScanner};
-pub(crate) use bitboard::{BitBoard, BitBoardBuilder};
-
-#[macro_export]
-macro_rules! bitboard {
-    ($($sq:ident),* $(,)?) => {
-        $crate::bitboard::BitBoardBuilder::empty()
-            $(.square($crate::Square::$sq))*
-            .build()
-    };
-}
diff --git a/board/src/lib.rs b/board/src/lib.rs
index 670368f..2ed3495 100644
--- a/board/src/lib.rs
+++ b/board/src/lib.rs
@@ -2,8 +2,6 @@
 
 pub mod fen;
 
-#[macro_use]
-mod bitboard;
 mod display;
 mod r#move;
 #[macro_use]

From b0b22048a8efdd120faaf7d350318162cccc19d7 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 08:48:19 -0800
Subject: [PATCH 08/12] =?UTF-8?q?[core]=20Rename=20(once=20again)=20chess?=
 =?UTF-8?q?=5Fcore=20=E2=86=92=20chessfriend=5Fcore?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Cargo.toml                                      |  2 +-
 bitboard/Cargo.toml                             |  2 +-
 bitboard/src/bitboard.rs                        |  2 +-
 bitboard/src/lib.rs                             |  2 +-
 bitboard/src/library.rs                         |  2 +-
 board/Cargo.toml                                |  2 +-
 board/src/fen.rs                                |  2 +-
 board/src/macros.rs                             |  2 +-
 board/src/move.rs                               | 14 +++++++-------
 board/src/move_generator/bishop.rs              |  2 +-
 board/src/move_generator/queen.rs               |  2 +-
 board/src/move_generator/rook.rs                |  4 ++--
 board/src/piece.rs                              |  2 +-
 board/src/position/builders/move_builder.rs     |  2 +-
 board/src/position/builders/position_builder.rs |  2 +-
 board/src/position/diagram_formatter.rs         |  2 +-
 board/src/position/piece_sets.rs                |  2 +-
 board/src/position/pieces.rs                    |  2 +-
 board/src/position/position.rs                  |  4 ++--
 board/src/sight.rs                              |  4 ++--
 core/Cargo.toml                                 |  2 +-
 21 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index a5661d8..7542226 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,6 @@
 members = [
     "board",
     "chess_bitboard",
-    "chess_core",
+    "chessfriend_core",
     "explorer",
 ]
diff --git a/bitboard/Cargo.toml b/bitboard/Cargo.toml
index 0670e94..e565de3 100644
--- a/bitboard/Cargo.toml
+++ b/bitboard/Cargo.toml
@@ -6,4 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-core = { path = "../core" }
+chessfriend_core = { path = "../core" }
diff --git a/bitboard/src/bitboard.rs b/bitboard/src/bitboard.rs
index 730c7c2..5be905a 100644
--- a/bitboard/src/bitboard.rs
+++ b/bitboard/src/bitboard.rs
@@ -2,7 +2,7 @@
 
 use crate::library::{library, FILES, RANKS};
 use crate::LeadingBitScanner;
-use chess_core::{Direction, Square};
+use chessfriend_core::{Direction, Square};
 use std::fmt;
 use std::ops::Not;
 
diff --git a/bitboard/src/lib.rs b/bitboard/src/lib.rs
index d3c0c4b..6b0703e 100644
--- a/bitboard/src/lib.rs
+++ b/bitboard/src/lib.rs
@@ -12,7 +12,7 @@ pub(crate) use bitboard::{BitBoard, BitBoardBuilder};
 macro_rules! bitboard {
     ($($sq:ident),* $(,)?) => {
         $crate::bitboard::BitBoardBuilder::empty()
-            $(.square(chess_core::Square::$sq))*
+            $(.square(chessfriend_core::Square::$sq))*
             .build()
     };
 }
diff --git a/bitboard/src/library.rs b/bitboard/src/library.rs
index 1e6a84d..506d6cd 100644
--- a/bitboard/src/library.rs
+++ b/bitboard/src/library.rs
@@ -1,7 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use super::BitBoard;
-use chess_core::{Direction, Square};
+use chessfriend_core::{Direction, Square};
 use std::sync::Once;
 
 pub(super) const RANKS: [BitBoard; 8] = [
diff --git a/board/Cargo.toml b/board/Cargo.toml
index da7df3c..2f8727d 100644
--- a/board/Cargo.toml
+++ b/board/Cargo.toml
@@ -6,4 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-chess_core = { path = "../chess_core" }
+chessfriend_core = { path = "../core" }
diff --git a/board/src/fen.rs b/board/src/fen.rs
index be63610..8610f00 100644
--- a/board/src/fen.rs
+++ b/board/src/fen.rs
@@ -5,7 +5,7 @@ use crate::{
     r#move::Castle,
     Color, Position,
 };
-use chess_core::{File, Rank, Square};
+use chessfriend_core::{File, Rank, Square};
 use std::fmt::Write;
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
diff --git a/board/src/macros.rs b/board/src/macros.rs
index ad69496..c6c374c 100644
--- a/board/src/macros.rs
+++ b/board/src/macros.rs
@@ -6,7 +6,7 @@ macro_rules! piece {
         $crate::piece::Piece::new($crate::piece::Color::$color, $crate::piece::Shape::$shape)
     };
     ($color:ident $shape:ident on $square:ident) => {
-        $crate::piece::PlacedPiece::new(piece!($color $shape), chess_core::Square::$square)
+        $crate::piece::PlacedPiece::new(piece!($color $shape), chessfriend_core::Square::$square)
     }
 }
 
diff --git a/board/src/move.rs b/board/src/move.rs
index c593b56..7b3e55c 100644
--- a/board/src/move.rs
+++ b/board/src/move.rs
@@ -1,7 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use crate::piece::{Piece, PlacedPiece, Shape};
-use chess_core::{Rank, Square};
+use chessfriend_core::{Rank, Square};
 use std::fmt;
 
 pub use castle::Castle;
@@ -18,7 +18,7 @@ pub enum MakeMoveError {
 
 mod castle {
     use crate::Color;
-    use chess_core::Square;
+    use chessfriend_core::Square;
 
     #[repr(u16)]
     #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -419,8 +419,8 @@ mod move_formatter {
                         $crate::piece::Color::$color,
                         $crate::piece::Shape::$shape,
                     ),
-                    chess_core::Square::$from_square,
-                    chess_core::Square::$to_square,
+                    chessfriend_core::Square::$from_square,
+                    chessfriend_core::Square::$to_square,
                 )
                 .build()
             };
@@ -430,15 +430,15 @@ mod move_formatter {
                         $crate::piece::Color::$color,
                         $crate::piece::Shape::$shape,
                     ),
-                    chess_core::Square::$from_square,
-                    chess_core::Square::$to_square,
+                    chessfriend_core::Square::$from_square,
+                    chessfriend_core::Square::$to_square,
                 )
                 .capturing($crate::piece::PlacedPiece::new(
                     $crate::piece::Piece::new(
                         $crate::piece::Color::$captured_color,
                         $crate::piece::Shape::$captured_shape,
                     ),
-                    chess_core::Square::$to_square,
+                    chessfriend_core::Square::$to_square,
                 ))
                 .build()
             };
diff --git a/board/src/move_generator/bishop.rs b/board/src/move_generator/bishop.rs
index 7bad274..cd259f7 100644
--- a/board/src/move_generator/bishop.rs
+++ b/board/src/move_generator/bishop.rs
@@ -5,7 +5,7 @@ use crate::{
     piece::{Color, Piece, PlacedPiece},
     BitBoard, MoveBuilder, Position,
 };
-use chess_core::Direction;
+use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
diff --git a/board/src/move_generator/queen.rs b/board/src/move_generator/queen.rs
index 10ad498..f012d8c 100644
--- a/board/src/move_generator/queen.rs
+++ b/board/src/move_generator/queen.rs
@@ -5,7 +5,7 @@ use crate::{
     piece::{Color, Piece, PlacedPiece},
     BitBoard, MoveBuilder, Position,
 };
-use chess_core::Direction;
+use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
diff --git a/board/src/move_generator/rook.rs b/board/src/move_generator/rook.rs
index 8ee6acd..c6dbb7b 100644
--- a/board/src/move_generator/rook.rs
+++ b/board/src/move_generator/rook.rs
@@ -5,7 +5,7 @@ use crate::{
     piece::{Color, Piece, PlacedPiece},
     BitBoard, MoveBuilder, Position,
 };
-use chess_core::Direction;
+use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
 
@@ -63,7 +63,7 @@ impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> {
 mod tests {
     use super::*;
     use crate::{piece::Piece, position, position::DiagramFormatter, BitBoard, Color, Position};
-    use chess_core::Square;
+    use chessfriend_core::Square;
 
     #[test]
     fn classical_single_rook_bitboard() {
diff --git a/board/src/piece.rs b/board/src/piece.rs
index cc91765..b80d1da 100644
--- a/board/src/piece.rs
+++ b/board/src/piece.rs
@@ -1,7 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use crate::display::{ASCIIDisplay, FENDisplay, UnicodeDisplay};
-use chess_core::Square;
+use chessfriend_core::Square;
 use std::fmt;
 use std::slice::Iter;
 
diff --git a/board/src/position/builders/move_builder.rs b/board/src/position/builders/move_builder.rs
index 2146e9d..17eb36d 100644
--- a/board/src/position/builders/move_builder.rs
+++ b/board/src/position/builders/move_builder.rs
@@ -6,7 +6,7 @@ use crate::{
     r#move::Castle,
     BitBoard, Color, MakeMoveError, Move, Piece, Position,
 };
-use chess_core::{Direction, Square};
+use chessfriend_core::{Direction, Square};
 
 /// A position builder that builds a new position by making a move.
 #[derive(Clone)]
diff --git a/board/src/position/builders/position_builder.rs b/board/src/position/builders/position_builder.rs
index 0410ca3..0866094 100644
--- a/board/src/position/builders/position_builder.rs
+++ b/board/src/position/builders/position_builder.rs
@@ -7,8 +7,8 @@ use crate::{
     r#move::Castle,
     BitBoard, Color, MakeMoveError, Move, Piece, Position,
 };
-use chess_core::{Rank, Square};
 use std::collections::BTreeMap;
+use chessfriend_core::Square;
 
 #[derive(Clone)]
 pub struct Builder {
diff --git a/board/src/position/diagram_formatter.rs b/board/src/position/diagram_formatter.rs
index ff4c3cf..0c46de4 100644
--- a/board/src/position/diagram_formatter.rs
+++ b/board/src/position/diagram_formatter.rs
@@ -1,7 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use crate::Position;
-use chess_core::{File, Rank, Square};
+use chessfriend_core::{File, Rank, Square};
 use std::fmt;
 
 pub struct DiagramFormatter<'a>(&'a Position);
diff --git a/board/src/position/piece_sets.rs b/board/src/position/piece_sets.rs
index fa08c84..856a3e8 100644
--- a/board/src/position/piece_sets.rs
+++ b/board/src/position/piece_sets.rs
@@ -4,7 +4,7 @@ use crate::{
     piece::{Piece, PlacedPiece},
     BitBoard, Color,
 };
-use chess_core::Square;
+use chessfriend_core::Square;
 
 #[derive(Debug, Eq, PartialEq)]
 pub enum PlacePieceStrategy {
diff --git a/board/src/position/pieces.rs b/board/src/position/pieces.rs
index 4e4495d..959a9da 100644
--- a/board/src/position/pieces.rs
+++ b/board/src/position/pieces.rs
@@ -3,7 +3,7 @@
 use super::Position;
 use crate::piece::{Color, Piece, PlacedPiece, Shape};
 use crate::BitBoard;
-use chess_core::Square;
+use chessfriend_core::Square;
 
 pub struct Pieces<'a> {
     color: Color,
diff --git a/board/src/position/position.rs b/board/src/position/position.rs
index ebc2948..e1f2f92 100644
--- a/board/src/position/position.rs
+++ b/board/src/position/position.rs
@@ -9,7 +9,7 @@ use crate::{
     sight::Sight,
     BitBoard, Move,
 };
-use chess_core::Square;
+use chessfriend_core::Square;
 use std::{cell::OnceCell, fmt};
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -268,7 +268,7 @@ impl fmt::Display for Position {
 #[cfg(test)]
 mod tests {
     use crate::{position, Castle, Color, Position};
-    use chess_core::Square;
+    use chessfriend_core::Square;
 
     #[test]
     fn piece_on_square() {
diff --git a/board/src/sight.rs b/board/src/sight.rs
index 7763bac..92b295f 100644
--- a/board/src/sight.rs
+++ b/board/src/sight.rs
@@ -4,7 +4,7 @@ use crate::{
     piece::{Color, PlacedPiece, Shape},
     BitBoard, Position,
 };
-use chess_core::Direction;
+use chessfriend_core::Direction;
 
 pub(crate) trait Sight {
     fn sight_in_position(&self, position: &Position) -> BitBoard;
@@ -175,7 +175,7 @@ mod tests {
 
     mod pawn {
         use crate::{sight::Sight, BitBoard};
-        use chess_core::Square;
+        use chessfriend_core::Square;
 
         sight_test!(e4_pawn, piece!(White Pawn on E4), bitboard!(D5, F5));
 
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 9b8c272..9b33128 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "chess_core"
+name = "chessfriend_core"
 version = "0.1.0"
 edition = "2021"
 

From 7738f30e5e51c487d6e1fca0d829e14684d9748c Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 09:14:59 -0800
Subject: [PATCH 09/12] Fix the workspace members

The items in the members array are paths, not crate names.
---
 Cargo.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 7542226..cfa9c81 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 
 members = [
     "board",
-    "chess_bitboard",
-    "chessfriend_core",
+    "bitboard",
+    "core",
     "explorer",
 ]

From d901be53d2ff45173e8be11319fa69740eb1c724 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 09:15:18 -0800
Subject: [PATCH 10/12] [explorer] Depends on core

---
 explorer/Cargo.toml  | 1 +
 explorer/src/main.rs | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/explorer/Cargo.toml b/explorer/Cargo.toml
index 5d49281..3f2513b 100644
--- a/explorer/Cargo.toml
+++ b/explorer/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+chessfriend_core = { path = "../core" }
 board = { path = "../board" }
 clap = { version = "4.4.12", features = ["derive"] }
 rustyline = "13.0.0"
diff --git a/explorer/src/main.rs b/explorer/src/main.rs
index 9da6a64..e8fca2f 100644
--- a/explorer/src/main.rs
+++ b/explorer/src/main.rs
@@ -1,5 +1,6 @@
 use board::piece::{Color, Piece, Shape};
-use board::{Position, Square};
+use board::Position;
+use chessfriend_core::Square;
 use clap::{Arg, Command};
 use rustyline::error::ReadlineError;
 use rustyline::DefaultEditor;

From 3cec64d6861d0b36fc88182e8ab1aa5d0c28a58d Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 09:16:21 -0800
Subject: [PATCH 11/12] [bitboard] Make the bitboard crate more crate-like

Export symbols needed to use BitBoard and BitBoardBuilder.
Fix build errors.
---
 bitboard/Cargo.toml      | 2 +-
 bitboard/src/bitboard.rs | 8 ++++----
 bitboard/src/lib.rs      | 5 +++--
 bitboard/src/library.rs  | 2 +-
 4 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/bitboard/Cargo.toml b/bitboard/Cargo.toml
index e565de3..df608b5 100644
--- a/bitboard/Cargo.toml
+++ b/bitboard/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "chess_bitboard"
+name = "chessfriend_bitboard"
 version = "0.1.0"
 edition = "2021"
 
diff --git a/bitboard/src/bitboard.rs b/bitboard/src/bitboard.rs
index 5be905a..6aa0df2 100644
--- a/bitboard/src/bitboard.rs
+++ b/bitboard/src/bitboard.rs
@@ -7,7 +7,7 @@ use std::fmt;
 use std::ops::Not;
 
 #[derive(Clone, Copy, Eq, Hash, PartialEq)]
-pub(crate) struct BitBoard(pub(super) u64);
+pub struct BitBoard(pub(crate) u64);
 
 macro_rules! moves_getter {
     ($getter_name:ident) => {
@@ -71,13 +71,13 @@ impl BitBoard {
 impl BitBoard {
     /// Return an Iterator over the occupied squares, starting from the leading
     /// (most-significant bit) end of the field.
-    pub(crate) fn occupied_squares(&self) -> impl Iterator<Item = Square> {
+    pub fn occupied_squares(&self) -> impl Iterator<Item = Square> {
         LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
     }
 
     /// Return an Iterator over the occupied squares, starting from the trailing
     /// (least-significant bit) end of the field.
-    pub(crate) fn occupied_squares_trailing(&self) -> impl Iterator<Item = Square> {
+    pub fn occupied_squares_trailing(&self) -> impl Iterator<Item = Square> {
         LeadingBitScanner::new(self.0).map(|idx| unsafe { Square::from_index(idx as u8) })
     }
 }
@@ -244,7 +244,7 @@ impl BitBoardBuilder {
 mod tests {
     use super::*;
     use crate::bitboard;
-    use chess_core::Square;
+    use chessfriend_core::Square;
 
     #[test]
     fn display_and_debug() {
diff --git a/bitboard/src/lib.rs b/bitboard/src/lib.rs
index 6b0703e..30a35f2 100644
--- a/bitboard/src/lib.rs
+++ b/bitboard/src/lib.rs
@@ -5,13 +5,14 @@ mod bitboard;
 mod library;
 mod shifts;
 
+pub use bitboard::{BitBoard, BitBoardBuilder};
+
 pub(crate) use bit_scanner::{LeadingBitScanner, TrailingBitScanner};
-pub(crate) use bitboard::{BitBoard, BitBoardBuilder};
 
 #[macro_export]
 macro_rules! bitboard {
     ($($sq:ident),* $(,)?) => {
-        $crate::bitboard::BitBoardBuilder::empty()
+        $crate::BitBoardBuilder::empty()
             $(.square(chessfriend_core::Square::$sq))*
             .build()
     };
diff --git a/bitboard/src/library.rs b/bitboard/src/library.rs
index 506d6cd..6c59291 100644
--- a/bitboard/src/library.rs
+++ b/bitboard/src/library.rs
@@ -1,6 +1,6 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use super::BitBoard;
+use crate::BitBoard;
 use chessfriend_core::{Direction, Square};
 use std::sync::Once;
 

From 6f85305912d6b8ca4cc290f6f6e7e2290ba9e145 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Wed, 24 Jan 2024 09:18:12 -0800
Subject: [PATCH 12/12] [board] Clean up a bunch of build errors

Fix imports to refer to core and bitboard crates.
Fix some API use errors.
---
 board/Cargo.toml                              |  1 +
 board/src/lib.rs                              |  2 --
 board/src/move_generator/bishop.rs            |  6 ++++--
 board/src/move_generator/king.rs              |  6 ++++--
 board/src/move_generator/knight.rs            |  6 ++++--
 board/src/move_generator/mod.rs               | 19 +++++++++++--------
 board/src/move_generator/move_generator.rs    |  3 ++-
 board/src/move_generator/move_set.rs          |  3 ++-
 board/src/move_generator/pawn.rs              |  6 ++++--
 board/src/move_generator/queen.rs             |  6 ++++--
 board/src/move_generator/rook.rs              |  6 ++++--
 board/src/position/builders/move_builder.rs   |  3 ++-
 .../src/position/builders/position_builder.rs |  9 ++++-----
 board/src/position/piece_sets.rs              |  5 +++--
 board/src/position/pieces.rs                  |  2 +-
 board/src/position/position.rs                |  3 ++-
 board/src/sight.rs                            |  9 +++++++--
 17 files changed, 59 insertions(+), 36 deletions(-)

diff --git a/board/Cargo.toml b/board/Cargo.toml
index 2f8727d..70584c2 100644
--- a/board/Cargo.toml
+++ b/board/Cargo.toml
@@ -7,3 +7,4 @@ edition = "2021"
 
 [dependencies]
 chessfriend_core = { path = "../core" }
+chessfriend_bitboard = { path = "../bitboard" }
diff --git a/board/src/lib.rs b/board/src/lib.rs
index 2ed3495..243686e 100644
--- a/board/src/lib.rs
+++ b/board/src/lib.rs
@@ -14,5 +14,3 @@ mod sight;
 pub use piece::{Color, Piece};
 pub use position::{MoveBuilder as MakeMoveBuilder, Position, PositionBuilder};
 pub use r#move::{Castle, MakeMoveError, Move, MoveBuilder};
-
-pub(crate) use bitboard::BitBoard;
diff --git a/board/src/move_generator/bishop.rs b/board/src/move_generator/bishop.rs
index cd259f7..404d68b 100644
--- a/board/src/move_generator/bishop.rs
+++ b/board/src/move_generator/bishop.rs
@@ -3,8 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    BitBoard, MoveBuilder, Position,
+    MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
@@ -60,7 +61,8 @@ impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{piece, piece::Color, position, position::DiagramFormatter, BitBoard};
+    use crate::{piece, piece::Color, position, position::DiagramFormatter};
+    use chessfriend_bitboard::BitBoard;
 
     #[test]
     fn classical_single_bishop_bitboard() {
diff --git a/board/src/move_generator/king.rs b/board/src/move_generator/king.rs
index 06ae76e..643a987 100644
--- a/board/src/move_generator/king.rs
+++ b/board/src/move_generator/king.rs
@@ -7,8 +7,9 @@ use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
     r#move::Castle,
-    BitBoard, Move, MoveBuilder, Position,
+    Move, MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 
 move_generator_declaration!(KingMoveGenerator, struct);
 move_generator_declaration!(KingMoveGenerator, new);
@@ -76,7 +77,8 @@ impl<'pos> MoveGeneratorInternal for KingMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Square;
+    use chessfriend_bitboard::bitboard;
+    use chessfriend_core::Square;
     use std::collections::HashSet;
 
     #[test]
diff --git a/board/src/move_generator/knight.rs b/board/src/move_generator/knight.rs
index 50a7ad0..64b360f 100644
--- a/board/src/move_generator/knight.rs
+++ b/board/src/move_generator/knight.rs
@@ -3,8 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    BitBoard, MoveBuilder, Position,
+    MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 
 move_generator_declaration!(KnightMoveGenerator);
 
@@ -40,7 +41,8 @@ impl<'pos> MoveGeneratorInternal for KnightMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{piece, position, Move, Square};
+    use crate::{piece, position, Move};
+    use chessfriend_core::Square;
     use std::collections::HashSet;
 
     #[test]
diff --git a/board/src/move_generator/mod.rs b/board/src/move_generator/mod.rs
index eb080c3..ed5ac74 100644
--- a/board/src/move_generator/mod.rs
+++ b/board/src/move_generator/mod.rs
@@ -14,8 +14,9 @@ pub(crate) use move_set::MoveSet;
 
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    Move, Position, Square,
+    Move, Position,
 };
+use chessfriend_core::Square;
 use std::collections::BTreeMap;
 
 trait MoveGenerator {
@@ -34,7 +35,10 @@ macro_rules! move_generator_declaration {
         pub(super) struct $name<'pos> {
             position: &'pos $crate::Position,
             color: $crate::piece::Color,
-            move_sets: std::collections::BTreeMap<$crate::Square, $crate::move_generator::MoveSet>,
+            move_sets: std::collections::BTreeMap<
+                chessfriend_core::Square,
+                $crate::move_generator::MoveSet,
+            >,
         }
     };
     ($name:ident, new) => {
@@ -54,12 +58,11 @@ macro_rules! move_generator_declaration {
                 self.move_sets.values().map(|set| set.moves()).flatten()
             }
 
-            fn bitboard(&self) -> $crate::BitBoard {
-                self.move_sets
-                    .values()
-                    .fold($crate::BitBoard::empty(), |partial, mv_set| {
-                        partial | mv_set.bitboard()
-                    })
+            fn bitboard(&self) -> chessfriend_bitboard::BitBoard {
+                self.move_sets.values().fold(
+                    chessfriend_bitboard::BitBoard::empty(),
+                    |partial, mv_set| partial | mv_set.bitboard(),
+                )
             }
         }
     };
diff --git a/board/src/move_generator/move_generator.rs b/board/src/move_generator/move_generator.rs
index 689e47d..2ef4922 100644
--- a/board/src/move_generator/move_generator.rs
+++ b/board/src/move_generator/move_generator.rs
@@ -43,7 +43,8 @@ impl<'a> Moves<'a> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{piece, position, r#move::AlgebraicMoveFormatter, Move, MoveBuilder, Square};
+    use crate::{piece, position, r#move::AlgebraicMoveFormatter, Move, MoveBuilder};
+    use chessfriend_core::Square;
     use std::collections::HashSet;
 
     #[test]
diff --git a/board/src/move_generator/move_set.rs b/board/src/move_generator/move_set.rs
index 1c44766..1c22eac 100644
--- a/board/src/move_generator/move_set.rs
+++ b/board/src/move_generator/move_set.rs
@@ -1,4 +1,5 @@
-use crate::{piece::PlacedPiece, BitBoard, Move};
+use crate::{piece::PlacedPiece, Move};
+use chessfriend_bitboard::BitBoard;
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 struct BitBoardSet {
diff --git a/board/src/move_generator/pawn.rs b/board/src/move_generator/pawn.rs
index 7f77e15..d366405 100644
--- a/board/src/move_generator/pawn.rs
+++ b/board/src/move_generator/pawn.rs
@@ -2,8 +2,9 @@
 
 use crate::{
     piece::{Color, Piece, Shape},
-    BitBoard, Move, MoveBuilder, Position,
+    Move, MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 
 enum MoveList {
     Quiet = 0,
@@ -246,7 +247,8 @@ impl<'pos> Iterator for PawnMoveGenerator<'pos> {
 mod tests {
     use super::*;
     use crate::position::DiagramFormatter;
-    use crate::{piece, Position, Square};
+    use crate::{piece, Position};
+    use chessfriend_core::Square;
     use std::collections::HashSet;
 
     #[test]
diff --git a/board/src/move_generator/queen.rs b/board/src/move_generator/queen.rs
index f012d8c..fb96dd7 100644
--- a/board/src/move_generator/queen.rs
+++ b/board/src/move_generator/queen.rs
@@ -3,8 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    BitBoard, MoveBuilder, Position,
+    MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
@@ -66,7 +67,8 @@ impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{piece, position, position::DiagramFormatter, BitBoard, Color};
+    use crate::{piece, position, position::DiagramFormatter, Color};
+    use chessfriend_bitboard::{bitboard, BitBoard};
 
     #[test]
     fn classical_single_queen_bitboard() {
diff --git a/board/src/move_generator/rook.rs b/board/src/move_generator/rook.rs
index c6dbb7b..570255a 100644
--- a/board/src/move_generator/rook.rs
+++ b/board/src/move_generator/rook.rs
@@ -3,8 +3,9 @@
 use super::{move_generator_declaration, MoveGeneratorInternal, MoveSet};
 use crate::{
     piece::{Color, Piece, PlacedPiece},
-    BitBoard, MoveBuilder, Position,
+    MoveBuilder, Position,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Direction;
 
 move_generator_declaration!(ClassicalMoveGenerator);
@@ -62,7 +63,8 @@ impl<'pos> MoveGeneratorInternal for ClassicalMoveGenerator<'pos> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{piece::Piece, position, position::DiagramFormatter, BitBoard, Color, Position};
+    use crate::{piece::Piece, position, position::DiagramFormatter, Color, Position};
+    use chessfriend_bitboard::{bitboard, BitBoard};
     use chessfriend_core::Square;
 
     #[test]
diff --git a/board/src/position/builders/move_builder.rs b/board/src/position/builders/move_builder.rs
index 17eb36d..4530543 100644
--- a/board/src/position/builders/move_builder.rs
+++ b/board/src/position/builders/move_builder.rs
@@ -4,8 +4,9 @@ use crate::{
     piece::{PlacedPiece, Shape},
     position::flags::Flags,
     r#move::Castle,
-    BitBoard, Color, MakeMoveError, Move, Piece, Position,
+    Color, MakeMoveError, Move, Piece, Position,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::{Direction, Square};
 
 /// A position builder that builds a new position by making a move.
diff --git a/board/src/position/builders/position_builder.rs b/board/src/position/builders/position_builder.rs
index 0866094..88838b7 100644
--- a/board/src/position/builders/position_builder.rs
+++ b/board/src/position/builders/position_builder.rs
@@ -1,14 +1,13 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use crate::{
-    bitboard::BitBoardBuilder,
     piece::{PlacedPiece, Shape},
     position::{flags::Flags, piece_sets::PieceBitBoards},
     r#move::Castle,
-    BitBoard, Color, MakeMoveError, Move, Piece, Position,
+    Color, MakeMoveError, Move, Piece, Position,
 };
+use chessfriend_core::{Rank, Square};
 use std::collections::BTreeMap;
-use chessfriend_core::Square;
 
 #[derive(Clone)]
 pub struct Builder {
@@ -109,8 +108,8 @@ impl Builder {
 
 impl Default for Builder {
     fn default() -> Self {
-        let white_king_square = Square::king_starting_square(Color::White);
-        let black_king_square = Square::king_starting_square(Color::Black);
+        let white_king_square = Square::E1;
+        let black_king_square = Square::E8;
 
         let pieces = BTreeMap::from_iter([
             (white_king_square, piece!(White King)),
diff --git a/board/src/position/piece_sets.rs b/board/src/position/piece_sets.rs
index 856a3e8..d07eb2a 100644
--- a/board/src/position/piece_sets.rs
+++ b/board/src/position/piece_sets.rs
@@ -2,8 +2,9 @@
 
 use crate::{
     piece::{Piece, PlacedPiece},
-    BitBoard, Color,
+    Color,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Square;
 
 #[derive(Debug, Eq, PartialEq)]
@@ -125,7 +126,7 @@ impl PieceBitBoards {
 
 impl FromIterator<PlacedPiece> for PieceBitBoards {
     fn from_iter<T: IntoIterator<Item = PlacedPiece>>(iter: T) -> Self {
-        let mut pieces = Self::default();
+        let mut pieces: Self = Default::default();
 
         for piece in iter {
             let _ = pieces.place_piece(&piece);
diff --git a/board/src/position/pieces.rs b/board/src/position/pieces.rs
index 959a9da..8530869 100644
--- a/board/src/position/pieces.rs
+++ b/board/src/position/pieces.rs
@@ -2,7 +2,7 @@
 
 use super::Position;
 use crate::piece::{Color, Piece, PlacedPiece, Shape};
-use crate::BitBoard;
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Square;
 
 pub struct Pieces<'a> {
diff --git a/board/src/position/position.rs b/board/src/position/position.rs
index e1f2f92..82ef1bd 100644
--- a/board/src/position/position.rs
+++ b/board/src/position/position.rs
@@ -7,8 +7,9 @@ use crate::{
     position::DiagramFormatter,
     r#move::Castle,
     sight::Sight,
-    BitBoard, Move,
+    Move,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Square;
 use std::{cell::OnceCell, fmt};
 
diff --git a/board/src/sight.rs b/board/src/sight.rs
index 92b295f..ffed3f7 100644
--- a/board/src/sight.rs
+++ b/board/src/sight.rs
@@ -2,8 +2,9 @@
 
 use crate::{
     piece::{Color, PlacedPiece, Shape},
-    BitBoard, Position,
+    Position,
 };
+use chessfriend_bitboard::BitBoard;
 use chessfriend_core::Direction;
 
 pub(crate) trait Sight {
@@ -174,7 +175,8 @@ mod tests {
     }
 
     mod pawn {
-        use crate::{sight::Sight, BitBoard};
+        use crate::sight::Sight;
+        use chessfriend_bitboard::{bitboard, BitBoard};
         use chessfriend_core::Square;
 
         sight_test!(e4_pawn, piece!(White Pawn on E4), bitboard!(D5, F5));
@@ -234,6 +236,7 @@ mod tests {
     #[macro_use]
     mod knight {
         use crate::sight::Sight;
+        use chessfriend_bitboard::bitboard;
 
         sight_test!(
             f6_knight,
@@ -244,6 +247,7 @@ mod tests {
 
     mod bishop {
         use crate::sight::Sight;
+        use chessfriend_bitboard::bitboard;
 
         sight_test!(
             c2_bishop,
@@ -254,6 +258,7 @@ mod tests {
 
     mod rook {
         use crate::sight::Sight;
+        use chessfriend_bitboard::bitboard;
 
         sight_test!(
             g3_rook,