Learn from clippy.

src/bin/ferry.rs

@@ -40,10 +40,12 @@ impl Into<char> for FerryLocation {
     }
 }
 
+type ViewerResult = Result<Vec<FerryLocation>, MapOperationError>;
+
 struct EvolvingMap {
     next_map: Option<Map<FerryLocation>>,
     occupation_tolerance: usize,
-    view: fn(&Map<FerryLocation>, usize, usize) -> Result<Vec<FerryLocation>, MapOperationError>,
+    view: fn(&Map<FerryLocation>, usize, usize) -> ViewerResult,
 }
 
 impl From<Map<FerryLocation>> for EvolvingMap {

src/bin/machine.rs

@@ -30,7 +30,7 @@ impl FromStr for Instruction {
         let instruction = items
             .next()
             .ok_or(InstructionParseError::EmptyInstruction)?;
-        let operand = items.next().ok_or(InstructionParseError::MissingOperand(
+        let operand = items.next().ok_or_else(|| InstructionParseError::MissingOperand(
             instruction.to_string(),
         ))?;
         let operand_value = isize::from_str(operand)?;
@@ -165,7 +165,7 @@ impl Iterator for VariantGenerator {
 }
 
 fn main() -> Result<(), TopLevelError> {
-    let filename = env::args().skip(1).next().expect("No file argument given.");
+    let filename = env::args().nth(1).expect("No file argument given.");
     let contents = fs::read_to_string(filename)?;
     let machine = Machine::from_str(&contents)?;
 

src/bin/xmas.rs

@@ -116,7 +116,7 @@ fn third_example() {
 }
 
 fn main() -> Result<(), TopLevelError> {
-    let filename = env::args().skip(1).next().expect("No file argument given.");
+    let filename = env::args().nth(1).expect("No file argument given.");
     let contents = fs::read_to_string(filename)?;
     let mut xmas_checker = XmasChecker::new(25);
 

src/map.rs

@@ -54,7 +54,7 @@ impl<X: Clone> Map<X> {
 
     pub fn at_unwrapped(&self, x: usize, y: usize) -> Option<X> {
         let row = self.data.get(y)?;
-        row.get(x).map(|x| x.clone())
+        row.get(x).cloned()
     }
 
     fn view(&self, f: fn(&X) -> bool, x: usize, y: usize, rise: isize, run: isize) -> Option<X> {
@@ -125,7 +125,7 @@ impl<X: Clone> Map<X> {
         Ok(results)
     }
 
-    pub fn locations<'a>(&'a self) -> MapLocations<'a, X> {
+    pub fn locations(&self) -> MapLocations<X> {
         MapLocations {
             underlying: self,
             x: 0,
@@ -176,7 +176,7 @@ impl<X: Clone + Into<char>> Map<X> {
             for x in 0..self.width {
                 print!("{}", self.at(x, y).unwrap().into());
             }
-            println!("");
+            println!();
         }
     }
 }