18 files changed, 344 insertions, 348 deletions

diff --git a/src/app.rs b/src/app.rs
index 33d4934..f42b48c 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -108,10 +108,10 @@ impl<'ctx> AppState<'ctx> {
         let y_min = self.start.y();
         let x_max = self.start.x() + (self.width() * self.zoom as u32) as i32;
         let y_max = self.start.y() + (self.height() * self.zoom as u32) as i32;
-        return (
+        (
             Point::new(x_min, y_min),
             Point::new(x_max as i32, y_max as i32),
-        );
+        )
     }
 
     pub fn change_active_color(&mut self) {
@@ -125,7 +125,7 @@ impl<'ctx> AppState<'ctx> {
             let rel_p = p - self.start;
             // reduce p based on zoom and cell size
             let (sx, sy) = (rel_p.x() / self.zoom as i32, rel_p.y() / self.zoom as i32);
-            return Some((sx as u32, sy as u32));
+            Some((sx as u32, sy as u32))
         } else {
             None
         }
@@ -254,7 +254,7 @@ impl<'ctx> AppState<'ctx> {
             let op = self
                 .current_operation
                 .drain(..)
-                .filter(|v| !v.old == v.new)
+                .filter(|v| v.old != v.new)
                 .collect::<Vec<_>>();
             self.undo_stack.push(ModifyRecord::Paint(op));
         }
@@ -267,7 +267,7 @@ impl<'ctx> AppState<'ctx> {
             let (x2, y2) = (p.0 * (1 + self.zoom as u32), p.1 * (1 + self.zoom as u32));
             let diffx = x2 as i32 - x1 as i32;
             let diffy = y2 as i32 - y1 as i32;
-            self.start = self.start - Point::from((diffx, diffy));
+            self.start -= Point::from((diffx, diffy));
         }
         self.zoom += 1;
     }
@@ -280,7 +280,7 @@ impl<'ctx> AppState<'ctx> {
                 let (x2, y2) = (p.0 * (self.zoom as u32 - 1), p.1 * (self.zoom as u32 - 1));
                 let diffx = x2 as i32 - x1 as i32;
                 let diffy = y2 as i32 - y1 as i32;
-                self.start = self.start - Point::from((diffx, diffy));
+                self.start -= Point::from((diffx, diffy));
             }
             self.zoom -= 1;
         }
@@ -310,7 +310,7 @@ impl<'ctx> AppState<'ctx> {
 
     pub fn eval_command(&mut self) {
         let lisp_expr = &self.command_box.text;
-        let mut parser = Parser::new(Lexer::new(lisp_expr, 0));
+        let mut parser = Parser::new(Lexer::new(lisp_expr));
         let res = parser.parse_single_expr();
         match res {
             Ok(expr) => {
@@ -393,7 +393,7 @@ impl<'ctx> AppState<'ctx> {
         let mouse_coords = if let Some((x, y)) = self.idx_at_coord(self.mouse) {
             format!("{:3}, {:3}", x + 1, y + 1)
         } else {
-            format!("---, ---")
+            String::from("---, ---")
         };
         let status_text = format!(
             "{} [PT {}][KIND {}]",
@@ -478,32 +478,29 @@ impl<'ctx> AppState<'ctx> {
                 }
             }
         }
-        match self.brush {
-            Brush::Line(LineBrush { start, size, .. }) => {
-                let size = self.zoom as u32 * (size as u32 + 5);
-                if let (Some(from), Some(to)) = (start, pt) {
-                    let line = self.pixmap.get_line(from, to.into());
-                    draw_text(
-                        &mut self.canvas,
-                        self.ttf_context,
-                        format!("{}°", positive_angle_with_x(from, to.into())),
-                        PINK,
-                        (self.mouse.0 + size as i32, self.mouse.1 + size as i32),
-                    );
-                    for MapPoint { x, y } in line.into_iter() {
-                        self.canvas.set_draw_color(PINK);
-                        self.canvas
-                            .fill_rect(Rect::new(
-                                x as i32 * cs as i32 + self.start.x(),
-                                y as i32 * cs as i32 + self.start.y(),
-                                cs,
-                                cs,
-                            ))
-                            .unwrap();
-                    }
+        if let Brush::Line(LineBrush { start, size, .. }) = self.brush {
+            let size = self.zoom as u32 * (size as u32 + 5);
+            if let (Some(from), Some(to)) = (start, pt) {
+                let line = self.pixmap.get_line(from, to.into());
+                draw_text(
+                    &mut self.canvas,
+                    self.ttf_context,
+                    format!("{}°", positive_angle_with_x(from, to.into())),
+                    PINK,
+                    (self.mouse.0 + size as i32, self.mouse.1 + size as i32),
+                );
+                for MapPoint { x, y } in line.into_iter() {
+                    self.canvas.set_draw_color(PINK);
+                    self.canvas
+                        .fill_rect(Rect::new(
+                            x as i32 * cs as i32 + self.start.x(),
+                            y as i32 * cs as i32 + self.start.y(),
+                            cs,
+                            cs,
+                        ))
+                        .unwrap();
                 }
             }
-            _ => {}
         }
     }
 
@@ -530,14 +527,12 @@ impl<'ctx> AppState<'ctx> {
 
     fn draw_symmetry(&mut self) {
         let Symmetry { x, y } = self.symmetry;
-        x.and_then(|line| {
-            self.draw_line_to_grid(line, Axis::X, CYAN);
-            Some(())
-        });
-        y.and_then(|line| {
-            self.draw_line_to_grid(line, Axis::Y, CYAN);
-            Some(())
-        });
+        if let Some(line) = x {
+            self.draw_line_to_grid(line, Axis::X, CYAN)
+        }
+        if let Some(line) = y {
+            self.draw_line_to_grid(line, Axis::Y, CYAN)
+        }
     }
 
     fn draw_guides(&mut self) {
@@ -626,7 +621,7 @@ impl<'ctx> AppState<'ctx> {
             .build()
             .map_err(|e| AppError::Sdl(e.to_string()))?;
 
-        let data = start_data.unwrap_or(vec![false; (width * height) as usize]);
+        let data = start_data.unwrap_or_else(|| vec![false; (width * height) as usize]);
         let pixmap = Pixmap::new_with(width, height, data);
         let mut app = Self {
             active_color: true,
@@ -668,7 +663,7 @@ impl<'ctx> AppState<'ctx> {
         let image = self.export().encode().unwrap();
         let mut file = File::create(file_name).map_err(AppError::File)?;
         file.write_all(&image[..]).map_err(AppError::File)?;
-        return Ok(());
+        Ok(())
     }
 
     pub fn run(&mut self) {
@@ -799,21 +794,21 @@ impl<'ctx> AppState<'ctx> {
                                         start,
                                         extend,
                                     }) => {
-                                        if start.is_none() {
+                                        if let Some(s) = start {
+                                            if let Ok(o) = self.paint_line(s, pt, val, size) {
+                                                self.current_operation.extend(o);
+                                                self.brush = Brush::Line(LineBrush {
+                                                    size,
+                                                    start: if extend { contact } else { None },
+                                                    extend,
+                                                });
+                                            }
+                                        } else {
                                             self.brush = Brush::Line(LineBrush {
                                                 size,
                                                 start: contact,
                                                 extend,
                                             });
-                                        } else if let Ok(o) =
-                                            self.paint_line(start.unwrap(), pt, val, size)
-                                        {
-                                            self.current_operation.extend(o);
-                                            self.brush = Brush::Line(LineBrush {
-                                                size,
-                                                start: if extend { contact } else { None },
-                                                extend,
-                                            });
                                         }
                                     }
                                     Brush::Fill => {
@@ -827,7 +822,7 @@ impl<'ctx> AppState<'ctx> {
                                             for o in operation.iter() {
                                                 // this `set` is unchecked because the returned
                                                 // value of flood_fill is checked to be within pixmap
-                                                self.pixmap.set(o.clone(), replacement);
+                                                self.pixmap.set(*o, replacement);
                                             }
                                             self.current_operation.extend(
                                                 operation
diff --git a/src/bitmap.rs b/src/bitmap.rs
index 8010a4b..2f96a99 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -29,7 +29,7 @@ impl TryFrom<(i32, i32)> for MapPoint {
     type Error = ();
     fn try_from((x, y): (i32, i32)) -> Result<Self, Self::Error> {
         if x < 0 || y < 0 {
-            return Err(());
+            Err(())
         } else {
             Ok(MapPoint {
                 x: x as u32,
@@ -43,7 +43,7 @@ impl TryFrom<(i64, i64)> for MapPoint {
     type Error = ();
     fn try_from((x, y): (i64, i64)) -> Result<Self, Self::Error> {
         if x < 0 || y < 0 {
-            return Err(());
+            Err(())
         } else {
             Ok(MapPoint {
                 x: x as u32,
@@ -79,18 +79,6 @@ pub enum Axis {
     Y,
 }
 
-impl Into<LispExpr> for Axis {
-    fn into(self) -> LispExpr {
-        LispExpr::Quote(
-            Box::new(LispExpr::Ident(match self {
-                Self::X => "X".into(),
-                Self::Y => "Y".into(),
-            })),
-            1,
-        )
-    }
-}
-
 impl TryFrom<&LispExpr> for Axis {
     type Error = EvalError;
     fn try_from(value: &LispExpr) -> Result<Self, Self::Error> {
@@ -224,7 +212,7 @@ where
                 circle.extend((x - dy.abs() + 1..x + dy.abs()).map(|x| (x, y + dx)));
                 circle.extend((x - dy.abs() + 1..x + dy.abs()).map(|x| (x, y - dx)));
             }
-            dy = dy + 1;
+            dy += 1;
             if err < 0 {
                 err = err + 2 * dy + 1;
             } else {
@@ -234,7 +222,7 @@ where
         }
         circle
             .into_iter()
-            .flat_map(|pt| MapPoint::try_from(pt))
+            .flat_map(MapPoint::try_from)
             .filter(|&pt| self.contains(pt))
             .collect()
     }
@@ -279,7 +267,7 @@ where
         }
         coordinates
             .into_iter()
-            .flat_map(|pt| MapPoint::try_from(pt))
+            .flat_map(MapPoint::try_from)
             .filter(|&pt| self.contains(pt))
             .collect()
     }
diff --git a/src/brush.rs b/src/brush.rs
index 8ff0cda..8557ba7 100644
--- a/src/brush.rs
+++ b/src/brush.rs
@@ -66,8 +66,8 @@ impl Brush {
 
     pub fn size(&self) -> Option<u8> {
         match self {
-            Brush::Line(LineBrush { size, .. }) => Some(size.clone()),
-            Brush::Circle(CircleBrush { size }) => Some(size.clone()),
+            Brush::Line(LineBrush { size, .. }) => Some(*size),
+            Brush::Circle(CircleBrush { size }) => Some(*size),
             _ => None,
         }
     }
diff --git a/src/cli.rs b/src/cli.rs
index 1dbd098..6357355 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -4,7 +4,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-pub static HELP_TEXT: &'static str = "
+pub static HELP_TEXT: &str = "
 Usage
 -----
 
@@ -83,11 +83,11 @@ pub fn parse_args() -> Result<Config, CliError> {
                 if !Path::new(s).is_file() {
                     return Err(CliError::FileDoesNotExist);
                 }
-                return Ok(Config::ExistingProject {
+                Ok(Config::ExistingProject {
                     file_name: PathBuf::from(s),
-                });
+                })
             }
-            None => return Ok(Config::Help),
+            None => Ok(Config::Help),
         },
         _ => Err(CliError::SubCommandParseError),
     }
@@ -104,25 +104,23 @@ fn new_project(args: &mut pico_args::Arguments) -> Result<Config, CliError> {
         .opt_value_from_fn(["-d", "--dimensions"], parse_dimensions)
         .map_err(|_| CliError::DimensionParseError)?
         .unwrap_or((200, 200));
-    return Ok(Config::NewProject {
+    Ok(Config::NewProject {
         file_name: file_name.ok(),
         dimensions,
-    });
+    })
 }
 
 fn parse_dimensions(input: &str) -> Result<(u32, u32), CliError> {
     let dimensions: Vec<&str> = input.split('x').collect();
     match &dimensions[..] {
-        [width, height] => {
-            return Ok((
-                width
-                    .parse::<u32>()
-                    .map_err(|_| CliError::DimensionParseError)?,
-                height
-                    .parse::<u32>()
-                    .map_err(|_| CliError::DimensionParseError)?,
-            ))
-        }
-        _ => return Err(CliError::DimensionParseError),
+        [width, height] => Ok((
+            width
+                .parse::<u32>()
+                .map_err(|_| CliError::DimensionParseError)?,
+            height
+                .parse::<u32>()
+                .map_err(|_| CliError::DimensionParseError)?,
+        )),
+        _ => Err(CliError::DimensionParseError),
     }
 }
diff --git a/src/command.rs b/src/command.rs
index 383389e..52ff7c8 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -111,7 +111,7 @@ impl CommandBox {
             return;
         }
         if let Some(idx) = self.hist_idx {
-            if !(idx + 1 >= self.history.items.len()) {
+            if idx + 1 < self.history.items.len() {
                 self.hist_idx = Some(idx + 1);
                 self.text = self.get_from_hist();
                 self.cursor_end();
@@ -138,6 +138,12 @@ impl CommandBox {
     }
 }
 
+impl std::default::Default for CommandBox {
+    fn default() -> Self {
+        CommandBox::new()
+    }
+}
+
 #[derive(Debug)]
 pub struct History<T> {
     pub items: Vec<T>,
diff --git a/src/consts.rs b/src/consts.rs
index 3f9ecb9..0b43f0a 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -8,6 +8,6 @@ pub mod colors {
     pub const PINK: Color = Color::RGB(255, 50, 153);
 }
 
-pub const FONT_PATH: &'static str = "./assets/NerdInput-Regular.ttf";
-pub const STDLIB_PATH: &'static str = "./src/lisp/std.lisp";
-pub const RC_PATH: &'static str = "/home/np/.config/sdl-tests";
+pub const FONT_PATH: &str = "./assets/NerdInput-Regular.ttf";
+pub const STDLIB_PATH: &str = "./src/lisp/std.lisp";
+pub const RC_PATH: &str = "/home/np/.config/sdl-tests";
diff --git a/src/dither.rs b/src/dither.rs
index 99e2839..25c59c8 100644
--- a/src/dither.rs
+++ b/src/dither.rs
@@ -26,16 +26,16 @@ pub fn bayer(level: u8, pt: MapPoint) -> bool {
         let MapPoint { x, y } = pt;
         let r = (x % 4, y % 4);
         match level {
-            01 => r == (0, 0) || bayer(00, pt),
-            02 => r == (2, 2) || bayer(01, pt),
-            03 => r == (0, 2) || bayer(02, pt),
-            04 => r == (2, 0) || bayer(03, pt),
-            05 => r == (1, 1) || bayer(04, pt),
-            06 => r == (3, 3) || bayer(05, pt),
-            07 => r == (1, 3) || bayer(06, pt),
-            08 => r == (3, 1) || bayer(07, pt),
-            09 => r == (0, 1) || bayer(08, pt),
-            10 => r == (0, 3) || bayer(09, pt),
+            1 => r == (0, 0) || bayer(0, pt),
+            2 => r == (2, 2) || bayer(1, pt),
+            3 => r == (0, 2) || bayer(2, pt),
+            4 => r == (2, 0) || bayer(3, pt),
+            5 => r == (1, 1) || bayer(4, pt),
+            6 => r == (3, 3) || bayer(5, pt),
+            7 => r == (1, 3) || bayer(6, pt),
+            8 => r == (3, 1) || bayer(7, pt),
+            9 => r == (0, 1) || bayer(8, pt),
+            10 => r == (0, 3) || bayer(9, pt),
             11 => r == (2, 3) || bayer(10, pt),
             12 => r == (2, 1) || bayer(11, pt),
             13 => r == (1, 0) || bayer(12, pt),
@@ -73,16 +73,16 @@ pub fn rylander(level: u8, pt: MapPoint) -> bool {
         let MapPoint { x, y } = pt;
         let r = (x % 4, y % 4);
         match level {
-            01 => r == (1, 3) || rylander(00, pt),
-            02 => r == (3, 1) || rylander(01, pt),
-            03 => r == (3, 3) || rylander(02, pt),
-            04 => r == (1, 1) || rylander(03, pt),
-            05 => r == (1, 2) || rylander(04, pt),
-            06 => r == (3, 0) || rylander(05, pt),
-            07 => r == (3, 2) || rylander(06, pt),
-            08 => r == (1, 0) || rylander(07, pt),
-            09 => r == (0, 3) || rylander(08, pt),
-            10 => r == (2, 1) || rylander(09, pt),
+            1 => r == (1, 3) || rylander(0, pt),
+            2 => r == (3, 1) || rylander(1, pt),
+            3 => r == (3, 3) || rylander(2, pt),
+            4 => r == (1, 1) || rylander(3, pt),
+            5 => r == (1, 2) || rylander(4, pt),
+            6 => r == (3, 0) || rylander(5, pt),
+            7 => r == (3, 2) || rylander(6, pt),
+            8 => r == (1, 0) || rylander(7, pt),
+            9 => r == (0, 3) || rylander(8, pt),
+            10 => r == (2, 1) || rylander(9, pt),
             11 => r == (2, 3) || rylander(10, pt),
             12 => r == (0, 1) || rylander(11, pt),
             13 => r == (0, 2) || rylander(12, pt),
diff --git a/src/guide.rs b/src/guide.rs
index 85d0594..0416e5c 100644
--- a/src/guide.rs
+++ b/src/guide.rs
@@ -1,21 +1,7 @@
-use crate::{
-    bitmap::Axis,
-    lisp::{expr::LispExpr, number::LispNumber},
-};
-
-use std::convert::Into;
+use crate::bitmap::Axis;
 
 #[derive(Debug, Hash, PartialEq, Eq, Copy, Clone)]
 pub struct Guide {
     pub axis: Axis,
     pub offset: u32,
 }
-
-impl Into<LispExpr> for Guide {
-    fn into(self) -> LispExpr {
-        LispExpr::List(vec![
-            self.axis.into(),
-            LispExpr::Number(LispNumber::Integer(self.offset as i64)),
-        ])
-    }
-}
diff --git a/src/lisp/eval.rs b/src/lisp/eval.rs
index 9276ef5..329b6ab 100644
--- a/src/lisp/eval.rs
+++ b/src/lisp/eval.rs
@@ -76,7 +76,7 @@ where
                                 self.eval(&LispExpr::List(f.body.clone()))
                             };
                             self.app.lisp_env.pop();
-                            return result;
+                            result
                         }
                     }
                     LispExpr::List(_) => {
@@ -108,7 +108,7 @@ where
                     error!("Unable to create global definition");
                     return Err(EvalError::BadForm.into());
                 }
-                return Ok(LispExpr::Unit);
+                Ok(LispExpr::Unit)
             }
             [LispExpr::List(shorthand), LispExpr::List(body)] => {
                 // (define (func arg) <body>) shorthand
@@ -130,12 +130,12 @@ where
 
                 let local_env = &mut self.app.lisp_env.last_mut();
                 if let Some(env) = local_env {
-                    env.insert(id.into(), value);
+                    env.insert(id, value);
                 } else {
                     error!("Unable to create global definition");
                     return Err(EvalError::BadForm.into());
                 }
-                return Ok(LispExpr::Unit);
+                Ok(LispExpr::Unit)
             }
             _ => {
                 error!("Invalid usage of `define`");
@@ -154,17 +154,16 @@ where
                 let value = self.eval(&expr)?;
                 let local_env = self.app.lisp_env.last_mut();
                 if let Some(env) = local_env {
-                    return env
-                        .insert(id.into(), value)
-                        .ok_or(EvalError::UnboundVariable(id.into()).into());
+                    env.insert(id.into(), value)
+                        .ok_or_else(|| EvalError::UnboundVariable(id.into()).into())
                 } else {
                     error!("Unable to set in global env!");
-                    return Err(EvalError::BadForm.into());
+                    Err(EvalError::BadForm.into())
                 }
             }
             _ => {
                 error!("Invalid usage of `set!`");
-                return Err(EvalError::BadForm.into());
+                Err(EvalError::BadForm.into())
             }
         }
     }
@@ -172,15 +171,15 @@ where
     pub fn eval_if(&mut self, args: &[LispExpr]) -> Result<LispExpr, LispError> {
         let arity = Arity::Exact(3);
         if !arity.check(args) {
-            return Err(arity.to_error());
+            Err(arity.to_error())
         } else {
             match args {
                 [predicate, then, else_] => {
                     let predicate = self.eval(&predicate)?;
                     if matches!(predicate, LispExpr::BoolLit(false)) {
-                        return self.eval(&else_);
+                        self.eval(&else_)
                     } else {
-                        return self.eval(&then);
+                        self.eval(&then)
                     }
                 }
                 _ => {
@@ -194,7 +193,7 @@ where
         let arity = Arity::Atleast(1);
         let valid_cond_stmt = |expr: &LispExpr| matches!(expr, LispExpr::List(v) if v.len() == 2);
         if !arity.check(args) {
-            return Err(arity.to_error());
+            Err(arity.to_error())
         } else {
             for cond_stmt in args {
                 if valid_cond_stmt(cond_stmt) {
@@ -211,7 +210,7 @@ where
                     return Err(EvalError::BadForm.into());
                 }
             }
-            return Ok(LispExpr::Unit);
+            Ok(LispExpr::Unit)
         }
     }
 
@@ -220,7 +219,7 @@ where
         let valid_binding_stmt =
             |expr: &LispExpr| matches!(expr, LispExpr::List(v) if v.len() == 2);
         if !arity.check(args) {
-            return Err(arity.to_error());
+            Err(arity.to_error())
         } else {
             let nested_env = Environment::new();
             self.app.lisp_env.push(nested_env);
@@ -247,11 +246,11 @@ where
                     }
                     let result = self.eval(&body);
                     self.app.lisp_env.pop();
-                    return result;
+                    result
                 }
                 _ => {
                     error!("bad `let` form");
-                    return Err(EvalError::BadForm.into());
+                    Err(EvalError::BadForm.into())
                 }
             }
         }
@@ -277,32 +276,28 @@ pub fn create_lambda(cdr: &[LispExpr]) -> Result<LispExpr, LispError> {
         return Err(arity.to_error());
     }
     match cdr {
-        [LispExpr::List(params), LispExpr::List(body)] if type_match!(params, (..) => LispExpr::Ident(_)) =>
-        {
-            return Ok(LispExpr::Function(LispFunction {
-                params: params
-                    .into_iter()
-                    .map(|p| p.unwrap_ident())
-                    .collect::<Vec<_>>(),
+        [LispExpr::List(params), LispExpr::List(body)] if type_match!(params, (..) => LispExpr::Ident(_)) => {
+            Ok(LispExpr::Function(LispFunction {
+                params: params.iter().map(|p| p.unwrap_ident()).collect::<Vec<_>>(),
                 body: body.clone(),
-            }));
+            }))
         }
         _ => {
             error!("Invalid usage of `lambda`");
-            return Err(EvalError::BadForm.into());
+            Err(EvalError::BadForm.into())
         }
     }
 }
 
 pub fn lookup(env_list: &[Environment], key: &str) -> Result<LispExpr, LispError> {
     if env_list.is_empty() {
-        return Err(EvalError::UnboundVariable(key.into()).into());
+        Err(EvalError::UnboundVariable(key.into()).into())
     } else {
         let local_env = env_list.last().unwrap();
         if let Some(val) = local_env.get(key) {
-            return Ok(val.clone());
+            Ok(val.clone())
         } else {
-            return lookup(&env_list[..env_list.len() - 1], key);
+            lookup(&env_list[..env_list.len() - 1], key)
         }
     }
 }
@@ -314,7 +309,7 @@ mod tests {
     use crate::lisp::{expr::LispExpr, lex::Lexer, number::LispNumber, parse::Parser};
 
     fn run(code: &str, app: &mut AppState) -> LispExpr {
-        let mut parser = Parser::new(Lexer::new(code, 0));
+        let mut parser = Parser::new(Lexer::new(code));
         let mut evaluator = Evaluator {
             app,
             context: Vec::new(),
diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index d2066e7..692f951 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -1,12 +1,18 @@
-use std::{cmp::PartialEq, convert::TryFrom, fmt};
+use std::{
+    cmp::PartialEq,
+    convert::{From, TryFrom},
+    fmt,
+};
 
 use crate::{
     app::AppState,
+    bitmap::Axis,
+    guide::Guide,
     lisp::{
         error::{EvalError, LispError},
         eval::lookup,
         number::LispNumber,
-        EnvList,
+        Environment,
     },
 };
 
@@ -113,7 +119,7 @@ impl LispExpr {
         }
     }
 
-    pub fn compare(&self, other: &Self, envs: &EnvList) -> Result<BoolLit, LispError> {
+    pub fn compare(&self, other: &Self, envs: &[Environment]) -> Result<BoolLit, LispError> {
         match (self, other) {
             (LispExpr::Unit, LispExpr::Unit) => Ok(true),
             (LispExpr::Number(s), LispExpr::Number(o)) => Ok(s == o),
@@ -121,8 +127,8 @@ impl LispExpr {
                 .iter()
                 .zip(o)
                 .all(|(a, b)| matches!(a.compare(b, envs), Ok(true)))),
-            (LispExpr::List(s), LispExpr::Unit) => Ok(s.len() == 0),
-            (LispExpr::Unit, LispExpr::List(s)) => Ok(s.len() == 0),
+            (LispExpr::List(s), LispExpr::Unit) => Ok(s.is_empty()),
+            (LispExpr::Unit, LispExpr::List(s)) => Ok(s.is_empty()),
             (LispExpr::StringLit(s), LispExpr::StringLit(o)) => Ok(s == o),
             (LispExpr::Char(s), LispExpr::Char(o)) => Ok(s == o),
             (LispExpr::BoolLit(s), LispExpr::BoolLit(o)) => Ok(s == o),
@@ -152,7 +158,7 @@ impl LispExpr {
     // have these be code gen'd somehow
     pub fn unwrap_number(&self) -> LispNumber {
         match &self {
-            LispExpr::Number(p) => p.clone(),
+            LispExpr::Number(p) => *p,
             _ => panic!("attempt to call `unwrap_number` on invalid type"),
         }
     }
@@ -200,10 +206,7 @@ impl LispExpr {
     }
 
     pub fn cast_bool(&self) -> bool {
-        match &self {
-            LispExpr::BoolLit(false) => false,
-            _ => true,
-        }
+        !matches!(self, LispExpr::BoolLit(false))
     }
 }
 
@@ -347,3 +350,26 @@ impl TryFrom<LispExpr> for BoolLit {
         }
     }
 }
+
+// conversion implementations
+
+impl From<Axis> for LispExpr {
+    fn from(axis: Axis) -> LispExpr {
+        LispExpr::Quote(
+            Box::new(LispExpr::Ident(match axis {
+                Axis::X => "X".into(),
+                Axis::Y => "Y".into(),
+            })),
+            1,
+        )
+    }
+}
+
+impl From<Guide> for LispExpr {
+    fn from(guide: Guide) -> LispExpr {
+        LispExpr::List(vec![
+            guide.axis.into(),
+            LispExpr::Number(LispNumber::Integer(guide.offset as i64)),
+        ])
+    }
+}
diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index 2088421..754a23f 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -102,16 +102,11 @@ impl<'src, 'file> SpanDisplay<'src, 'file> {
 pub struct Lexer<'input> {
     input: &'input str,
     cur_pos: u32,
-    offset: u32,
 }
 
 impl<'a> Lexer<'a> {
-    pub fn new(input: &'a str, offset: u32) -> Self {
-        Self {
-            input,
-            cur_pos: 0,
-            offset,
-        }
+    pub fn new(input: &'a str) -> Self {
+        Self { input, cur_pos: 0 }
     }
 
     pub fn next_token(&mut self) -> Result<(Span, Token<'a>), ParseError> {
@@ -166,11 +161,11 @@ impl<'a> Lexer<'a> {
             return Ok((sp, token));
         }
         self.input = &self.input[..0];
-        return Ok((Span::empty(self.cur_pos), Token::End));
+        Ok((Span::empty(self.cur_pos), Token::End))
     }
 }
 
-fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
+fn parse_number(mut input: &str) -> Result<(usize, Token<'_>), ParseErrorKind> {
     let mut dot = false;
     let mut minus = false;
     let mut size = 0;
@@ -186,7 +181,7 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), ParseError
         }
     }
 
-    while let Some(chr) = chars.next() {
+    for chr in chars {
         if chr.is_digit(10) {
             size += 1;
         } else if chr == '.' {
@@ -210,10 +205,10 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), ParseError
     } else {
         Token::Integer(&input[..size])
     };
-    return Ok((size, tok));
+    Ok((size, tok))
 }
 
-fn parse_string<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
+fn parse_string(input: &str) -> Result<(usize, Token<'_>), ParseErrorKind> {
     // count opening quote
     let mut size = 1;
     let mut closed = false;
@@ -260,7 +255,7 @@ fn consume_comment(start: usize, chars: &mut CharIndices) -> usize {
     last - start + 1
 }
 
-fn parse_name<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
+fn parse_name(input: &str) -> Result<(usize, Token<'_>), ParseErrorKind> {
     for (ind, chr) in input.char_indices() {
         if !is_ident(chr) {
             return Ok((ind, Token::Name(&input[..ind])));
@@ -269,7 +264,7 @@ fn parse_name<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind>
     return Ok((input.len(), Token::Name(input)));
 }
 
-fn parse_char<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
+fn parse_char(input: &str) -> Result<(usize, Token<'_>), ParseErrorKind> {
     // first two chars of input are '#' and '\'
     let chr = &input[..3];
     return Ok((chr.len(), Token::Char(chr)));
@@ -284,7 +279,7 @@ mod tests {
     }
 
     fn tokens(input: &str) -> Vec<(Span, Token)> {
-        let mut lexer = Lexer::new(input, 0);
+        let mut lexer = Lexer::new(input);
         let mut tokens = Vec::new();
         loop {
             match lexer.next_token().unwrap() {
diff --git a/src/lisp/number.rs b/src/lisp/number.rs
index 4ca890a..4824e21 100644
--- a/src/lisp/number.rs
+++ b/src/lisp/number.rs
@@ -16,14 +16,14 @@ impl LispNumber {
     pub fn div(self, rhs: Self) -> Result<LispNumber, LispError> {
         use LispNumber::*;
         if rhs == Integer(0) || rhs == Float(0.) {
-            return Err(EvalError::DivByZero.into());
+            Err(EvalError::DivByZero.into())
         } else {
-            return Ok(match (self, rhs) {
+            Ok(match (self, rhs) {
                 (Integer(a), Integer(b)) => Float(a as f64 / b as f64),
                 (Float(a), Integer(b)) => Float(a / b as f64),
                 (Integer(a), Float(b)) => Float(a as f64 / b),
                 (Float(a), Float(b)) => Float(a / b),
-            });
+            })
         }
     }
     pub fn unwrap_integer(self) -> i64 {
diff --git a/src/lisp/parse.rs b/src/lisp/parse.rs
index 737e7ad..8aeb672 100644
--- a/src/lisp/parse.rs
+++ b/src/lisp/parse.rs
@@ -1,5 +1,5 @@
 use crate::lisp::{
-    error::{LispError, ParseError, ParseErrorKind},
+    error::{ParseError, ParseErrorKind},
     lex::{Lexer, Span, Token},
     number::LispNumber,
     LispExpr,
@@ -30,97 +30,91 @@ impl<'lex> Parser<'lex> {
         let mut total_backticks = 0;
         loop {
             let (span, token) = self.next()?;
-            let r: Result<LispExpr, ParseError> = match token {
-                Token::LeftParen => {
-                    stack.push(Group::Parens(Vec::new()));
-                    continue;
-                }
-                Token::RightParen => {
-                    let group = stack
-                        .pop()
-                        .ok_or_else(|| (ParseError::new(span, ParseErrorKind::UnmatchedParen)))?;
-                    match group {
-                        Group::Parens(v) => {
-                            if v.len() == 0 {
-                                Ok(LispExpr::Unit)
-                            } else {
-                                Ok(LispExpr::List(v))
+            let r: Result<LispExpr, ParseError> =
+                match token {
+                    Token::LeftParen => {
+                        stack.push(Group::Parens(Vec::new()));
+                        continue;
+                    }
+                    Token::RightParen => {
+                        let group = stack
+                            .pop()
+                            .ok_or_else(|| ParseError::new(span, ParseErrorKind::UnmatchedParen))?;
+                        match group {
+                            Group::Parens(v) => {
+                                if v.is_empty() {
+                                    Ok(LispExpr::Unit)
+                                } else {
+                                    Ok(LispExpr::List(v))
+                                }
                             }
+                            _ => Err(ParseError::new(
+                                span,
+                                ParseErrorKind::UnexpectedToken {
+                                    expected: "expression",
+                                    found: "(",
+                                },
+                            )),
                         }
-                        _ => Err(From::from(ParseError::new(
-                            span,
-                            ParseErrorKind::UnexpectedToken {
-                                expected: "expression",
-                                found: "(",
-                            },
-                        ))),
                     }
-                }
-                Token::Float(f) => f
-                    .parse::<f64>()
-                    .map(|n| LispExpr::Number(LispNumber::Float(n)))
-                    .map_err(|_| ParseError::new(span, ParseErrorKind::LiteralParseError).into()),
-                Token::Integer(i) => i
-                    .parse::<i64>()
-                    .map(|n| LispExpr::Number(LispNumber::Integer(n)))
-                    .map_err(|_| ParseError::new(span, ParseErrorKind::LiteralParseError).into()),
-                Token::String(s) => Ok(LispExpr::StringLit(s[1..s.len() - 1].into())),
-                Token::Char(s) => {
-                    Ok(LispExpr::Char(s.chars().nth(2).ok_or_else(|| {
+                    Token::Float(f) => f
+                        .parse::<f64>()
+                        .map(|n| LispExpr::Number(LispNumber::Float(n)))
+                        .map_err(|_| ParseError::new(span, ParseErrorKind::LiteralParseError)),
+                    Token::Integer(i) => i
+                        .parse::<i64>()
+                        .map(|n| LispExpr::Number(LispNumber::Integer(n)))
+                        .map_err(|_| ParseError::new(span, ParseErrorKind::LiteralParseError)),
+                    Token::String(s) => Ok(LispExpr::StringLit(s[1..s.len() - 1].into())),
+                    Token::Char(s) => Ok(LispExpr::Char(s.chars().nth(2).ok_or_else(|| {
                         ParseError::new(span, ParseErrorKind::LiteralParseError)
-                    })?))
-                }
-                Token::Name(n) => Ok(name_expr(n)),
-                Token::BackQuote => {
-                    total_backticks += 1;
-                    if let Some(&mut Group::Backticks(ref mut n)) = stack.last_mut() {
-                        *n += 1;
+                    })?)),
+                    Token::Name(n) => Ok(name_expr(n)),
+                    Token::BackQuote => {
+                        total_backticks += 1;
+                        if let Some(&mut Group::Backticks(ref mut n)) = stack.last_mut() {
+                            *n += 1;
+                            continue;
+                        }
+                        stack.push(Group::Backticks(1));
                         continue;
                     }
-                    stack.push(Group::Backticks(1));
-                    continue;
-                }
-                Token::Comma => {
-                    if total_backticks <= 0 {
-                        return Err(ParseError::new(span, ParseErrorKind::UnbalancedComma));
-                    }
-                    total_backticks -= 1;
-                    if let Some(&mut Group::Backticks(ref mut n)) = stack.last_mut() {
-                        *n -= 1;
+                    Token::Comma => {
+                        if total_backticks <= 0 {
+                            return Err(ParseError::new(span, ParseErrorKind::UnbalancedComma));
+                        }
+                        total_backticks -= 1;
+                        if let Some(&mut Group::Backticks(ref mut n)) = stack.last_mut() {
+                            *n -= 1;
+                            continue;
+                        }
+                        stack.push(Group::Backticks(-1));
                         continue;
                     }
-                    stack.push(Group::Backticks(-1));
-                    continue;
-                }
-                Token::CommaAt => {
-                    if total_backticks <= 0 {
-                        return Err(ParseError::new(span, ParseErrorKind::UnbalancedComma));
+                    Token::CommaAt => {
+                        if total_backticks <= 0 {
+                            return Err(ParseError::new(span, ParseErrorKind::UnbalancedComma));
+                        }
+                        total_backticks -= 1;
+                        stack.push(Group::CommaAt);
+                        continue;
                     }
-                    total_backticks -= 1;
-                    stack.push(Group::CommaAt);
-                    continue;
-                }
-                Token::Quote => {
-                    if let Some(&mut Group::Quotes(ref mut n)) = stack.last_mut() {
-                        *n += 1;
+                    Token::Quote => {
+                        if let Some(&mut Group::Quotes(ref mut n)) = stack.last_mut() {
+                            *n += 1;
+                            continue;
+                        }
+                        stack.push(Group::Quotes(1));
                         continue;
                     }
-                    stack.push(Group::Quotes(1));
-                    continue;
-                }
-                Token::End => {
-                    let any_paren = stack.iter().any(|group| match *group {
-                        Group::Parens(_) => true,
-                        _ => false,
-                    });
-
-                    if any_paren {
-                        Err(ParseError::new(span, ParseErrorKind::MissingCloseParen))
-                    } else {
-                        Err(ParseError::new(span, ParseErrorKind::UnexpectedEof))
+                    Token::End => {
+                        if stack.iter().any(|group| matches!(*group, Group::Parens(_))) {
+                            Err(ParseError::new(span, ParseErrorKind::MissingCloseParen))
+                        } else {
+                            Err(ParseError::new(span, ParseErrorKind::UnexpectedEof))
+                        }
                     }
-                }
-            };
+                };
             let mut v = r?;
             loop {
                 match stack.last_mut() {
@@ -181,8 +175,7 @@ impl<'lex> Parser<'lex> {
                     expected: "EOF",
                     found: token.name(),
                 },
-            )
-            .into()),
+            )),
         }
     }
 
@@ -210,7 +203,7 @@ fn name_expr(input: &str) -> LispExpr {
 mod tests {
     use super::*;
     fn parse(input: &str) -> Result<LispExpr, ParseError> {
-        let mut parser = Parser::new(Lexer::new(input, 0));
+        let mut parser = Parser::new(Lexer::new(input));
 
         parser.parse_single_expr()
     }
diff --git a/src/lisp/prelude.rs b/src/lisp/prelude.rs
index aebff98..fee787e 100644
--- a/src/lisp/prelude.rs
+++ b/src/lisp/prelude.rs
@@ -66,7 +66,7 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "+", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
         return Ok(LispExpr::Number(
@@ -76,10 +76,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "-", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let mut acc = nums[0].clone();
+        let mut acc = *nums[0];
         for arg in nums.into_iter().skip(1) {
             acc = acc - *arg;
         }
@@ -88,7 +88,7 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "*", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
         return Ok(LispExpr::Number(
@@ -98,10 +98,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "/", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let mut acc = nums[0].clone();
+        let mut acc = *nums[0];
         for arg in nums.into_iter().skip(1) {
             acc = acc.div(*arg)?;
         }
@@ -139,7 +139,7 @@ pub fn new_env() -> Result<Environment, LispError> {
     });
 
     primitive!(env, Arity::Atleast(1), "begin", |args, _| {
-        Ok(args.into_iter().last().unwrap().clone())
+        Ok(args.iter().last().unwrap().clone())
     });
 
     primitive!(env, Arity::Exact(0), "quit", |_, app| {
@@ -157,8 +157,8 @@ pub fn new_env() -> Result<Environment, LispError> {
             (LispExpr::DottedList(s), LispExpr::DottedList(o)) => {
                 Ok(s.iter().zip(o).all(|(a, b)| a == b))
             }
-            (LispExpr::List(s), LispExpr::Unit) => Ok(s.len() == 0),
-            (LispExpr::Unit, LispExpr::List(s)) => Ok(s.len() == 0),
+            (LispExpr::List(s), LispExpr::Unit) => Ok(s.is_empty()),
+            (LispExpr::Unit, LispExpr::List(s)) => Ok(s.is_empty()),
             (LispExpr::DottedList(_), LispExpr::Unit) => Ok(false),
             (LispExpr::Unit, LispExpr::DottedList(_)) => Ok(false),
             (LispExpr::StringLit(s), LispExpr::StringLit(o)) => Ok(s == o),
@@ -176,10 +176,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), ">", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let acc = nums[0].clone();
+        let acc = *nums[0];
         Ok(LispExpr::BoolLit(
             nums.into_iter().skip(1).all(|&arg| acc > arg),
         ))
@@ -187,10 +187,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), ">=", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let acc = nums[0].clone();
+        let acc = *nums[0];
         Ok(LispExpr::BoolLit(
             nums.into_iter().skip(1).all(|&arg| acc >= arg),
         ))
@@ -198,10 +198,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "<", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let acc = nums[0].clone();
+        let acc = *nums[0];
         Ok(LispExpr::BoolLit(
             nums.into_iter().skip(1).all(|&arg| acc < arg),
         ))
@@ -209,10 +209,10 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Atleast(2), "<=", |args, _| {
         let nums = args
-            .into_iter()
+            .iter()
             .map(|arg| arg.try_into())
             .collect::<Result<Vec<&LispNumber>, LispError>>()?;
-        let acc = nums[0].clone();
+        let acc = *nums[0];
         Ok(LispExpr::BoolLit(
             nums.into_iter().skip(1).all(|&arg| acc <= arg),
         ))
@@ -235,18 +235,16 @@ pub fn new_env() -> Result<Environment, LispError> {
                 .map_err(|e| LispError::Stringified(e.to_string()))
                 .map(|_| LispExpr::Unit);
         }
-        return Err(EvalError::NoFileName.into());
+        Err(EvalError::NoFileName.into())
     });
 
     primitive!(env, Arity::Exact(1), "save-as", |args, app| {
         match &args[0] {
-            LispExpr::StringLit(s) => {
-                return app
-                    .save_as(&s)
-                    .map_err(|e| LispError::Stringified(e.to_string()))
-                    .map(|_| LispExpr::Unit);
-            }
-            _ => return Err(EvalError::TypeMismatch.into()),
+            LispExpr::StringLit(s) => app
+                .save_as(&s)
+                .map_err(|e| LispError::Stringified(e.to_string()))
+                .map(|_| LispExpr::Unit),
+            _ => Err(EvalError::TypeMismatch.into()),
         }
     });
 
@@ -261,52 +259,52 @@ pub fn new_env() -> Result<Environment, LispError> {
 
     primitive!(env, Arity::Exact(0), "brush-fill", |_, app| {
         app.brush = Brush::Fill;
-        return Ok(LispExpr::Unit);
+        Ok(LispExpr::Unit)
     });
 
     primitive!(env, Arity::Exact(0), "brush-circle", |_, app| {
         app.brush = Brush::new(0);
-        return Ok(LispExpr::Unit);
+        Ok(LispExpr::Unit)
     });
 
     primitive!(env, Arity::Exact(0), "brush-line", |_, app| {
         app.brush = Brush::line(0, false);
-        return Ok(LispExpr::Unit);
+        Ok(LispExpr::Unit)
     });
 
     primitive!(env, Arity::Exact(0), "brush-line-extend", |_, app| {
         app.brush = Brush::line(0, true);
-        return Ok(LispExpr::Unit);
+        Ok(LispExpr::Unit)
     });
 
     primitive!(env, Arity::Exact(2), "cons", |args, _| {
         if type_match!(args, 1 => LispExpr::Unit) {
-            return Ok(LispExpr::List(vec![args[0].clone()]));
+            Ok(LispExpr::List(vec![args[0].clone()]))
         } else if type_match!(args, 1 => LispExpr::DottedList(_)) {
             // cons of anything to an improper list is an improper list
             let mut rest = args[1].unwrap_dotted_list();
             rest.insert(0, args[0].clone());
-            return Ok(LispExpr::DottedList(rest));
+            Ok(LispExpr::DottedList(rest))
         } else if type_match!(args, 1 => LispExpr::List(_)) {
             // cons of anything to a proper list is a proper list
             let mut rest = args[1].unwrap_list();
             rest.insert(0, args[0].clone());
-            return Ok(LispExpr::List(rest));
+            Ok(LispExpr::List(rest))
         } else {
             // attempt to cons non-lists
-            return Ok(LispExpr::DottedList(vec![args[0].clone(), args[1].clone()]));
+            Ok(LispExpr::DottedList(vec![args[0].clone(), args[1].clone()]))
         }
     });
 
     primitive!(env, Arity::Exact(1), "car", |args, _| {
         if type_match!(args, 0 => LispExpr::List(_)) {
-            return Ok(args[0].unwrap_list().swap_remove(0));
+            Ok(args[0].unwrap_list().swap_remove(0))
         } else if type_match!(args, 0 => LispExpr::DottedList(_)) {
-            return Ok(args[0].unwrap_dotted_list().swap_remove(0));
+            Ok(args[0].unwrap_dotted_list().swap_remove(0))
         } else if type_match!(args, 0 => LispExpr::Unit) {
-            return Err(EvalError::AccessEmptyList.into());
+            Err(EvalError::AccessEmptyList.into())
         } else {
-            return Err(EvalError::TypeMismatch.into());
+            Err(EvalError::TypeMismatch.into())
         }
     });
 
@@ -314,32 +312,32 @@ pub fn new_env() -> Result<Environment, LispError> {
         if type_match!(args, 0 => LispExpr::List(_)) {
             // cdr of a proper list is a proper list
             let mut ls = args[0].unwrap_list();
-            if ls.len() == 0 {
-                return Err(EvalError::AccessEmptyList.into());
+            if ls.is_empty() {
+                Err(EvalError::AccessEmptyList.into())
             } else if ls.len() == 1 {
-                return Ok(LispExpr::Unit);
+                Ok(LispExpr::Unit)
             } else {
                 ls.remove(0);
-                return Ok(LispExpr::List(ls));
+                Ok(LispExpr::List(ls))
             }
         } else if type_match!(args, 0 => LispExpr::DottedList(_)) {
             // cdr of an improper list is an improper list or an atom
             let ls = args[0].unwrap_dotted_list();
             if ls.len() == 2 {
-                return Ok(ls.into_iter().last().unwrap());
+                Ok(ls.into_iter().last().unwrap())
             } else {
                 // should be unreachable
-                return Err(EvalError::AccessEmptyList.into());
+                Err(EvalError::AccessEmptyList.into())
             }
         } else if type_match!(args, 0 => LispExpr::Unit) {
-            return Err(EvalError::AccessEmptyList.into());
+            Err(EvalError::AccessEmptyList.into())
         } else {
-            return Err(EvalError::TypeMismatch.into());
+            Err(EvalError::TypeMismatch.into())
         }
     });
 
     primitive!(env, Arity::Atleast(1), "list", |args, _| {
-        return Ok(LispExpr::List(args.to_vec()));
+        Ok(LispExpr::List(args.to_vec()))
     });
 
     primitive!(env, Arity::Exact(1), "load-script", |args, app| {
@@ -347,40 +345,40 @@ pub fn new_env() -> Result<Environment, LispError> {
             let path = args[0].unwrap_stringlit();
             load_script(&path, app).map(|_| LispExpr::Unit)
         } else {
-            return Err(EvalError::TypeMismatch.into());
+            Err(EvalError::TypeMismatch.into())
         }
     });
 
     primitive!(env, Arity::Atleast(1), "error", |args, _| {
         if type_match!(args, 0 => LispExpr::StringLit(_)) {
-            let mut s = String::from(args[0].unwrap_stringlit());
-            for arg in args.into_iter().skip(1) {
+            let mut s = args[0].unwrap_stringlit();
+            for arg in args.iter().skip(1) {
                 s.push_str(&format!(" {}", arg));
             }
-            return Err(EvalError::Custom(s).into());
+            Err(EvalError::Custom(s).into())
         } else {
-            return Err(EvalError::TypeMismatch.into());
+            Err(EvalError::TypeMismatch.into())
         }
     });
 
     primitive!(env, Arity::Exact(2), "assert-eq", |args, app| {
         if args[0].compare(&args[1], &app.lisp_env)? {
-            return Ok(LispExpr::Unit);
+            Ok(LispExpr::Unit)
         } else {
-            return Err(EvalError::AssertionError {
+            Err(EvalError::AssertionError {
                 expected: args[0].clone(),
                 got: args[1].clone(),
             }
-            .into());
+            .into())
         }
     });
 
     primitive!(env, Arity::Exact(0), "canvas-width", |_, app| {
-        return Ok(LispExpr::Number(LispNumber::Integer(app.width() as i64)));
+        Ok(LispExpr::Number(LispNumber::Integer(app.width() as i64)))
     });
 
     primitive!(env, Arity::Exact(0), "canvas-height", |_, app| {
-        return Ok(LispExpr::Number(LispNumber::Integer(app.height() as i64)));
+        Ok(LispExpr::Number(LispNumber::Integer(app.height() as i64)))
     });
 
     primitive!(env, Arity::Exact(3), "set-pixel!", |args, app| {
@@ -397,21 +395,21 @@ pub fn new_env() -> Result<Environment, LispError> {
                 .try_into()
                 .map_err(|_| -> LispError { EvalError::InvalidCoordinates((x, y)).into() })?;
             if !app.pixmap.contains(set_loc) {
-                return Err(EvalError::InvalidCoordinates((x, y)).into());
+                Err(EvalError::InvalidCoordinates((x, y)).into())
             } else {
                 let old_val = app.pixmap.set(set_loc, val);
                 app.current_operation
                     .push(PaintRecord::new(set_loc, old_val, val));
-                return Ok(LispExpr::Unit);
+                Ok(LispExpr::Unit)
             }
         } else {
-            return Err(EvalError::TypeMismatch.into());
+            Err(EvalError::TypeMismatch.into())
         }
     });
 
     primitive!(env, Arity::Exact(0), "commit", |_, app| {
         app.commit_operation();
-        return Ok(LispExpr::Unit);
+        Ok(LispExpr::Unit)
     });
 
     primitive!(env, Arity::Exact(2), "add-guide!", |args, app| {
@@ -422,9 +420,9 @@ pub fn new_env() -> Result<Environment, LispError> {
                     offset: *offset as u32,
                 };
                 app.guides.insert(guide, true);
-                return Ok(LispExpr::Unit);
+                Ok(LispExpr::Unit)
             }
-            _ => return Err(EvalError::TypeMismatch.into()),
+            _ => Err(EvalError::TypeMismatch.into()),
         }
     });
 
diff --git a/src/main.rs b/src/main.rs
index 9370abf..245ee83 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+#![allow(clippy::upper_case_acronyms, clippy::vec_init_then_push)]
 mod app;
 mod bitmap;
 mod brush;
@@ -62,13 +63,12 @@ pub fn error_sink() -> Result<(), AppError> {
             .run();
         }
     }
-    return Ok(());
+    Ok(())
 }
 
 pub fn main() {
     env_logger::init();
-    match error_sink() {
-        Err(e) => error!("{}", e),
-        _ => (),
+    if let Err(e) = error_sink() {
+        error!("{}", e);
     }
 }
diff --git a/src/message.rs b/src/message.rs
index 958dd68..b090b4d 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -67,13 +67,19 @@ where
     }
 }
 
-impl Into<Color> for MessageKind {
-    fn into(self) -> Color {
-        match self {
-            Self::Error => PINK,
-            Self::Info => WHITE,
-            Self::Hint => CYAN,
-            Self::LispResult => GREY,
+impl std::default::Default for Message {
+    fn default() -> Self {
+        Message::new()
+    }
+}
+
+impl From<MessageKind> for Color {
+    fn from(msg: MessageKind) -> Color {
+        match msg {
+            MessageKind::Error => PINK,
+            MessageKind::Info => WHITE,
+            MessageKind::Hint => CYAN,
+            MessageKind::LispResult => GREY,
         }
     }
 }
diff --git a/src/undo.rs b/src/undo.rs
index 1044c63..5effd79 100644
--- a/src/undo.rs
+++ b/src/undo.rs
@@ -67,9 +67,10 @@ where
         if let Some(p) = self.position {
             self.position = p.checked_sub(1);
             // we want to return a clone and not a reference because push deletes the item
-            return Some(self.operations[p as usize].clone());
+            Some(self.operations[p as usize].clone())
+        } else {
+            None
         }
-        return None;
     }
 
     pub fn redo(&mut self) -> Option<T> {
@@ -82,7 +83,16 @@ where
             self.position = Some(0);
             return Some(self.operations[0].clone());
         }
-        return None;
+        None
+    }
+}
+
+impl<T> std::default::Default for UndoStack<T>
+where
+    T: Clone,
+{
+    fn default() -> Self {
+        UndoStack::new()
     }
 }
 
diff --git a/src/utils.rs b/src/utils.rs
index ab446f4..8c3b144 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -46,7 +46,7 @@ pub fn draw_text<S: AsRef<str>>(
     font.set_style(sdl2::ttf::FontStyle::NORMAL);
     font.set_hinting(sdl2::ttf::Hinting::Mono);
     let surface = font
-        .render(if text.is_empty() { " " } else { text.as_ref() })
+        .render(if text.is_empty() { " " } else { text })
         .blended(color)
         .unwrap();
     let texture = texture_creator
@@ -84,7 +84,7 @@ pub fn load_script<P: AsRef<Path>>(path: P, app: &mut AppState) -> Result<(), Li
         .read_to_string(&mut buf)
         .map_err(EvalError::ScriptLoadError)?;
 
-    let mut parser = Parser::new(Lexer::new(&buf, 0));
+    let mut parser = Parser::new(Lexer::new(&buf));
     let mut evaluator = Evaluator {
         app,
         context: Vec::new(),
@@ -94,7 +94,7 @@ pub fn load_script<P: AsRef<Path>>(path: P, app: &mut AppState) -> Result<(), Li
     })? {
         evaluator.eval(&expr)?;
     }
-    return Ok(());
+    Ok(())
 }
 
 pub fn load_file<P: AsRef<Path>>(path: P) -> Result<Image, io::Error> {