fixed some clippy warnings

5 files changed, 187 insertions, 188 deletions

diff --git a/src/context.rs b/src/context.rs
index 9fb3bf4..c2e1913 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -34,7 +34,7 @@ impl<'i, T> Context<'i, T> {
     }
 
     pub fn map<U, F: Fn(&T) -> U>(&self, f: F) -> Context<'i, U> {
-        Context(self.0.iter().map(|(k, v)| (k.clone(), v.iter().map(&f).collect())).collect())
+        Context(self.0.iter().map(|(k, v)| (*k, v.iter().map(&f).collect())).collect())
     }
 }
 
@@ -43,7 +43,7 @@ impl<'i, T: Clone> Context<'i, T> {
     pub fn insert(&self, k: &'i str, v: T) -> Self {
         let mut ctx = (*self).clone();
         {
-            let m = ctx.0.entry(k).or_insert(vec![]);
+            let m = ctx.0.entry(k).or_insert_with(Vec::new);
             m.push(v);
         }
         ctx
diff --git a/src/core.rs b/src/core.rs
index 02ff6ac..a9de523 100644
--- a/src/core.rs
+++ b/src/core.rs
@@ -257,22 +257,22 @@ impl<'i, S, A> From<BuiltinValue> for Expr<'i, S, A> {
 
 impl<'i, S, A> Expr<'i, S, A> {
     fn bool_lit(&self) -> Option<bool> {
-        match self {
-            &Expr::BoolLit(v) => Some(v),
+        match *self {
+            Expr::BoolLit(v) => Some(v),
             _ => None,
         }
     }
 
     fn natural_lit(&self) -> Option<usize> {
-        match self {
-            &Expr::NaturalLit(v) => Some(v),
+        match *self {
+            Expr::NaturalLit(v) => Some(v),
             _ => None,
         }
     }
 
     fn text_lit(&self) -> Option<String> {
-        match self {
-            &Expr::TextLit(ref t) => Some(t.clone()), // FIXME?
+        match *self {
+            Expr::TextLit(ref t) => Some(t.clone()), // FIXME?
             _ => None,
         }
     }
@@ -423,7 +423,7 @@ impl<'i, S, A: Display> Expr<'i, S, A> {
                 fmt_list("{ ", " }", a, f, |(k, v), f| write!(f, "{} = {}", k, v))
             }
             &Union(ref _a) => f.write_str("Union"),
-            &UnionLit(ref _a, ref _b, ref _c) => f.write_str("UnionLit"),
+            &UnionLit(_a, ref _b, ref _c) => f.write_str("UnionLit"),
             &Embed(ref a) => a.fmt(f),
             &Note(_, ref b) => b.fmt_f(f),
             a => write!(f, "({})", a),
@@ -531,7 +531,7 @@ pub fn bx<T>(x: T) -> Box<T> {
 
 fn add_ui(u: usize, i: isize) -> usize {
     if i < 0 {
-        u.checked_sub((i.checked_neg().unwrap() as usize)).unwrap()
+        u.checked_sub(i.checked_neg().unwrap() as usize).unwrap()
     } else {
         u.checked_add(i as usize).unwrap()
     }
@@ -627,75 +627,75 @@ fn map_op2<T, U, V, F, G>(f: F, g: G, a: T, b: T) -> V
 pub fn shift<'i, S, T, A: Clone>(d: isize, v: V, e: &Expr<'i, S, A>) -> Expr<'i, T, A> {
     use Expr::*;
     let V(x, n) = v;
-    match e {
-        &Const(a) => Const(a),
-        &Var(V(x2, n2)) => {
+    match *e {
+        Const(a) => Const(a),
+        Var(V(x2, n2)) => {
             let n3 = if x == x2 && n <= n2 { add_ui(n2, d) } else { n2 };
             Var(V(x2, n3))
         }
-        &Lam(x2, ref tA, ref b) => {
+        Lam(x2, ref tA, ref b) => {
             let n2 = if x == x2 { n + 1 } else { n };
             let tA2 = shift(d, V(x, n ), tA);
             let b2  = shift(d, V(x, n2), b);
             Lam(x2, bx(tA2), bx(b2))
         }
-        &Pi(x2, ref tA, ref tB) => {
+        Pi(x2, ref tA, ref tB) => {
             let n2 = if x == x2 { n + 1 } else { n };
             let tA2 = shift(d, V(x, n ), tA);
             let tB2 = shift(d, V(x, n2), tB);
             pi(x2, tA2, tB2)
         }
-        &App(ref f, ref a) => app(shift(d, v, f), shift(d, v, a)),
-        &Let(f, ref mt, ref r, ref e) => {
+        App(ref f, ref a) => app(shift(d, v, f), shift(d, v, a)),
+        Let(f, ref mt, ref r, ref e) => {
             let n2 = if x == f { n + 1 } else { n };
             let e2 = shift(d, V(x, n2), e);
             let mt2 = mt.as_ref().map(|t| bx(shift(d, V(x, n), t)));
             let r2  = shift(d, V(x, n), r);
             Let(f, mt2, bx(r2), bx(e2))
         }
-        &Annot(ref a, ref b) => shift_op2(Annot, d, v, a, b),
-        &BuiltinType(t) => BuiltinType(t),
-        &BuiltinValue(v) => BuiltinValue(v),
-        &BoolLit(a) => BoolLit(a),
-        &BoolAnd(ref a, ref b) => shift_op2(BoolAnd, d, v, a, b),
-        &BoolOr(ref a, ref b) => shift_op2(BoolOr, d, v, a, b),
-        &BoolEQ(ref a, ref b) => shift_op2(BoolEQ, d, v, a, b),
-        &BoolNE(ref a, ref b) => shift_op2(BoolNE, d, v, a, b),
-        &BoolIf(ref a, ref b, ref c) => {
+        Annot(ref a, ref b) => shift_op2(Annot, d, v, a, b),
+        BuiltinType(t) => BuiltinType(t),
+        BuiltinValue(v) => BuiltinValue(v),
+        BoolLit(a) => BoolLit(a),
+        BoolAnd(ref a, ref b) => shift_op2(BoolAnd, d, v, a, b),
+        BoolOr(ref a, ref b) => shift_op2(BoolOr, d, v, a, b),
+        BoolEQ(ref a, ref b) => shift_op2(BoolEQ, d, v, a, b),
+        BoolNE(ref a, ref b) => shift_op2(BoolNE, d, v, a, b),
+        BoolIf(ref a, ref b, ref c) => {
             BoolIf(bx(shift(d, v, a)), bx(shift(d, v, b)), bx(shift(d, v, c)))
         }
-        &NaturalLit(a) => NaturalLit(a),
-        &NaturalPlus(ref a, ref b) => NaturalPlus(bx(shift(d, v, a)), bx(shift(d, v, b))),
-        &NaturalTimes(ref a, ref b) => shift_op2(NaturalTimes, d, v, a, b),
-        &IntegerLit(a) => IntegerLit(a),
-        &DoubleLit(a) => DoubleLit(a),
-        &TextLit(ref a) => TextLit(a.clone()),
-        &TextAppend(ref a, ref b) => shift_op2(TextAppend, d, v, a, b),
-        &ListLit(ref t, ref es) => {
+        NaturalLit(a) => NaturalLit(a),
+        NaturalPlus(ref a, ref b) => NaturalPlus(bx(shift(d, v, a)), bx(shift(d, v, b))),
+        NaturalTimes(ref a, ref b) => shift_op2(NaturalTimes, d, v, a, b),
+        IntegerLit(a) => IntegerLit(a),
+        DoubleLit(a) => DoubleLit(a),
+        TextLit(ref a) => TextLit(a.clone()),
+        TextAppend(ref a, ref b) => shift_op2(TextAppend, d, v, a, b),
+        ListLit(ref t, ref es) => {
             ListLit(bx(shift(d, v, t)),
                     es.iter().map(|e| shift(d, v, e)).collect())
         }
-        &OptionalLit(ref t, ref es) => {
+        OptionalLit(ref t, ref es) => {
             OptionalLit(bx(shift(d, v, t)),
                         es.iter().map(|e| shift(d, v, e)).collect())
         }
-        &Record(ref a) => Record(map_record_value(a, |val| shift(d, v, val))),
-        &RecordLit(ref a) => RecordLit(map_record_value(a, |val| shift(d, v, val))),
-        &Union(ref a) => Union(map_record_value(a, |val| shift(d, v, val))),
-        &UnionLit(k, ref uv, ref a) => {
+        Record(ref a) => Record(map_record_value(a, |val| shift(d, v, val))),
+        RecordLit(ref a) => RecordLit(map_record_value(a, |val| shift(d, v, val))),
+        Union(ref a) => Union(map_record_value(a, |val| shift(d, v, val))),
+        UnionLit(k, ref uv, ref a) => {
             UnionLit(k,
                      bx(shift(d, v, uv)),
                      map_record_value(a, |val| shift(d, v, val)))
         }
-        &Combine(ref a, ref b) => shift_op2(Combine, d, v, a, b),
-        &Merge(ref a, ref b, ref c) => {
+        Combine(ref a, ref b) => shift_op2(Combine, d, v, a, b),
+        Merge(ref a, ref b, ref c) => {
             Merge(bx(shift(d, v, a)), bx(shift(d, v, b)), bx(shift(d, v, c)))
         }
-        &Field(ref a, b) => Field(bx(shift(d, v, a)), b),
-        &Note(_, ref b) => shift(d, v, b),
+        Field(ref a, b) => Field(bx(shift(d, v, a)), b),
+        Note(_, ref b) => shift(d, v, b),
         // The Dhall compiler enforces that all embedded values are closed expressions
         // and `shift` does nothing to a closed expression
-        &Embed(ref p) => Embed(p.clone()),
+        Embed(ref p) => Embed(p.clone()),
     }
 }
 
@@ -723,76 +723,76 @@ pub fn subst<'i, S, T, A>(v: V<'i>, e: &Expr<'i, S, A>, b: &Expr<'i, T, A>) -> E
 {
     use Expr::*;
     let V(x, n) = v;
-    match b {
-        &Const(a) => Const(a),
-        &Lam(y, ref tA, ref b) => {
+    match *b {
+        Const(a) => Const(a),
+        Lam(y, ref tA, ref b) => {
             let n2  = if x == y { n + 1 } else { n };
-            let b2  = subst(V(x, n2), &shift(1, V(y, 0), &e), b);
-            let tA2 = subst(V(x, n),                     &e, tA);
+            let b2  = subst(V(x, n2), &shift(1, V(y, 0), e), b);
+            let tA2 = subst(V(x, n),                     e, tA);
             Lam(y, bx(tA2), bx(b2))
         }
-        &Pi(y, ref tA, ref tB) => {
+        Pi(y, ref tA, ref tB) => {
             let n2  = if x == y { n + 1 } else { n };
-            let tB2 = subst(V(x, n2), &shift(1, V(y, 0), &e), tB);
-            let tA2 = subst(V(x, n),                     &e,  tA);
+            let tB2 = subst(V(x, n2), &shift(1, V(y, 0), e), tB);
+            let tA2 = subst(V(x, n),                     e,  tA);
             pi(y, tA2, tB2)
         }
-        &App(ref f, ref a) => {
+        App(ref f, ref a) => {
             let f2 = subst(v, e, f);
             let a2 = subst(v, e, a);
             app(f2, a2)
         }
-        &Var(v2) => if v == v2 { e.clone() } else { Var(v2) },
-        &Let(f, ref mt, ref r, ref b) => {
+        Var(v2) => if v == v2 { e.clone() } else { Var(v2) },
+        Let(f, ref mt, ref r, ref b) => {
             let n2 = if x == f { n + 1 } else { n };
             let b2 = subst(V(x, n2), &shift(1, V(f, 0), e), b);
             let mt2 = mt.as_ref().map(|t| bx(subst(V(x, n), e, t)));
             let r2  = subst(V(x, n), e, r);
             Let(f, mt2, bx(r2), bx(b2))
         }
-        &Annot(ref a, ref b) => subst_op2(Annot, v, e, a, b),
-        &BuiltinType(t) => BuiltinType(t),
-        &BuiltinValue(v) => BuiltinValue(v),
-        &BoolLit(a) => BoolLit(a),
-        &BoolAnd(ref a, ref b) => subst_op2(BoolAnd, v, e, a, b),
-        &BoolOr(ref a, ref b) => subst_op2(BoolOr, v, e, a, b),
-        &BoolEQ(ref a, ref b) => subst_op2(BoolEQ, v, e, a, b),
-        &BoolNE(ref a, ref b) => subst_op2(BoolNE, v, e, a, b),
-        &BoolIf(ref a, ref b, ref c) => {
+        Annot(ref a, ref b) => subst_op2(Annot, v, e, a, b),
+        BuiltinType(t) => BuiltinType(t),
+        BuiltinValue(v) => BuiltinValue(v),
+        BoolLit(a) => BoolLit(a),
+        BoolAnd(ref a, ref b) => subst_op2(BoolAnd, v, e, a, b),
+        BoolOr(ref a, ref b) => subst_op2(BoolOr, v, e, a, b),
+        BoolEQ(ref a, ref b) => subst_op2(BoolEQ, v, e, a, b),
+        BoolNE(ref a, ref b) => subst_op2(BoolNE, v, e, a, b),
+        BoolIf(ref a, ref b, ref c) => {
             BoolIf(bx(subst(v, e, a)), bx(subst(v, e, b)), bx(subst(v, e, c)))
         }
-        &NaturalLit(a) => NaturalLit(a),
-        &NaturalPlus(ref a, ref b) => subst_op2(NaturalPlus, v, e, a, b),
-        &NaturalTimes(ref a, ref b) => subst_op2(NaturalTimes, v, e, a, b),
-        &IntegerLit(a) => IntegerLit(a),
-        &DoubleLit(a) => DoubleLit(a),
-        &TextLit(ref a) => TextLit(a.clone()),
-        &TextAppend(ref a, ref b) => subst_op2(TextAppend, v, e, a, b),
-        &ListLit(ref a, ref b) => {
+        NaturalLit(a) => NaturalLit(a),
+        NaturalPlus(ref a, ref b) => subst_op2(NaturalPlus, v, e, a, b),
+        NaturalTimes(ref a, ref b) => subst_op2(NaturalTimes, v, e, a, b),
+        IntegerLit(a) => IntegerLit(a),
+        DoubleLit(a) => DoubleLit(a),
+        TextLit(ref a) => TextLit(a.clone()),
+        TextAppend(ref a, ref b) => subst_op2(TextAppend, v, e, a, b),
+        ListLit(ref a, ref b) => {
             let a2 = subst(v, e, a);
             let b2 = b.iter().map(|be| subst(v, e, be)).collect();
             ListLit(bx(a2), b2)
         }
-        &OptionalLit(ref a, ref b) => {
+        OptionalLit(ref a, ref b) => {
             let a2 = subst(v, e, a);
             let b2 = b.iter().map(|be| subst(v, e, be)).collect();
             OptionalLit(bx(a2), b2)
         }
-        &Record(ref kts) => Record(map_record_value(kts, |t| subst(v, e, t))),
-        &RecordLit(ref kvs) => RecordLit(map_record_value(kvs, |val| subst(v, e, val))),
-        &Union(ref kts) => Union(map_record_value(kts, |t| subst(v, e, t))),
-        &UnionLit(k, ref uv, ref kvs) => {
+        Record(ref kts) => Record(map_record_value(kts, |t| subst(v, e, t))),
+        RecordLit(ref kvs) => RecordLit(map_record_value(kvs, |val| subst(v, e, val))),
+        Union(ref kts) => Union(map_record_value(kts, |t| subst(v, e, t))),
+        UnionLit(k, ref uv, ref kvs) => {
             UnionLit(k,
                      bx(subst(v, e, uv)),
                      map_record_value(kvs, |val| subst(v, e, val)))
         }
-        &Combine(ref a, ref b) => subst_op2(Combine, v, e, a, b),
-        &Merge(ref a, ref b, ref c) => {
+        Combine(ref a, ref b) => subst_op2(Combine, v, e, a, b),
+        Merge(ref a, ref b, ref c) => {
             Merge(bx(subst(v, e, a)), bx(subst(v, e, b)), bx(subst(v, e, c)))
         }
-        &Field(ref a, b) => Field(bx(subst(v, e, a)), b),
-        &Note(_, ref b) => subst(v, e, b),
-        &Embed(ref p) => Embed(p.clone()),
+        Field(ref a, b) => Field(bx(subst(v, e, a)), b),
+        Note(_, ref b) => subst(v, e, b),
+        Embed(ref p) => Embed(p.clone()),
     }
 }
 
@@ -825,20 +825,20 @@ pub fn normalize<'i, S, T, A>(e: &Expr<'i, S, A>) -> Expr<'i, T, A>
 {
     use BuiltinValue::*;
     use Expr::*;
-    match e {
-        &Const(k) => Const(k),
-        &Var(v) => Var(v),
-        &Lam(x, ref tA, ref b) => {
+    match *e {
+        Const(k) => Const(k),
+        Var(v) => Var(v),
+        Lam(x, ref tA, ref b) => {
             let tA2 = normalize(tA);
             let b2  = normalize(b);
             Lam(x, bx(tA2), bx(b2))
         }
-        &Pi(x, ref tA, ref tB) => {
+        Pi(x, ref tA, ref tB) => {
             let tA2 = normalize(tA);
             let tB2 = normalize(tB);
             pi(x, tA2, tB2)
         }
-        &App(ref f, ref a) => match normalize::<S, T, A>(f) {
+        App(ref f, ref a) => match normalize::<S, T, A>(f) {
             Lam(x, _A, b) => { // Beta reduce
                 let vx0 = V(x, 0);
                 let a2 = shift::<S, S, A>( 1, vx0, a);
@@ -848,11 +848,11 @@ pub fn normalize<'i, S, T, A>(e: &Expr<'i, S, A>) -> Expr<'i, T, A>
             }
             f2 => match (f2, normalize::<S, T, A>(a)) {
                 // fold/build fusion for `List`
-                (App(box BuiltinValue(ListBuild), _), App(box App(box BuiltinValue(ListFold), _), box e2)) => normalize(&e2),
-                (App(box BuiltinValue(ListFold), _), App(box App(box BuiltinValue(ListBuild), _), box e2)) => normalize(&e2),
+                (App(box BuiltinValue(ListBuild), _), App(box App(box BuiltinValue(ListFold), _), box e2)) |
+                (App(box BuiltinValue(ListFold), _), App(box App(box BuiltinValue(ListBuild), _), box e2)) |
 
                 // fold/build fusion for `Natural`
-                (BuiltinValue(NaturalBuild), App(box BuiltinValue(NaturalFold), box e2)) => normalize(&e2),
+                (BuiltinValue(NaturalBuild), App(box BuiltinValue(NaturalFold), box e2)) |
                 (BuiltinValue(NaturalFold), App(box BuiltinValue(NaturalBuild), box e2)) => normalize(&e2),
 
             /*
@@ -900,9 +900,9 @@ pub fn normalize<'i, S, T, A>(e: &Expr<'i, S, A>) -> Expr<'i, T, A>
                             }
                         }
                         fn check<S, A>(e: &Expr<S, A>) -> bool {
-                            match e {
-                                &App(box App(box Var(V("Cons", _)), _), ref e2) => check(e2),
-                                &Var(V("Nil", _)) => true,
+                            match *e {
+                                App(box App(box Var(V("Cons", _)), _), ref e2) => check(e2),
+                                Var(V("Nil", _)) => true,
                                 _ => false,
                             }
                         }
@@ -958,85 +958,85 @@ pub fn normalize<'i, S, T, A>(e: &Expr<'i, S, A>) -> Expr<'i, T, A>
                 (f2, a2) => app(f2, a2),
             }
         },
-        &Let(f, _, ref r, ref b) => {
+        Let(f, _, ref r, ref b) => {
             let r2 = shift::<_, S, _>( 1, V(f, 0), r);
             let b2 = subst(V(f, 0), &r2, b);
             let b3 = shift::<_, T, _>(-1, V(f, 0), &b2);
             normalize(&b3)
         }
-        &Annot(ref x, _) => normalize(x),
-        &BuiltinType(t) => BuiltinType(t),
-        &BuiltinValue(v) => BuiltinValue(v),
-        &BoolLit(b) => BoolLit(b),
-        &BoolAnd(ref x, ref y) => {
+        Annot(ref x, _) => normalize(x),
+        BuiltinType(t) => BuiltinType(t),
+        BuiltinValue(v) => BuiltinValue(v),
+        BoolLit(b) => BoolLit(b),
+        BoolAnd(ref x, ref y) => {
             with_binop(BoolAnd, Expr::bool_lit,
                        |xn, yn| BoolLit(xn && yn),
                        normalize(x), normalize(y))
         }
-        &BoolOr(ref x, ref y) => {
+        BoolOr(ref x, ref y) => {
             with_binop(BoolOr, Expr::bool_lit,
                        |xn, yn| BoolLit(xn || yn),
                        normalize(x), normalize(y))
         }
-        &BoolEQ(ref x, ref y) => {
+        BoolEQ(ref x, ref y) => {
             with_binop(BoolEQ, Expr::bool_lit,
                        |xn, yn| BoolLit(xn == yn),
                        normalize(x), normalize(y))
         }
-        &BoolNE(ref x, ref y) => {
+        BoolNE(ref x, ref y) => {
             with_binop(BoolNE, Expr::bool_lit,
                        |xn, yn| BoolLit(xn != yn),
                        normalize(x), normalize(y))
         }
-        &BoolIf(ref b, ref t, ref f) => match normalize(b) {
+        BoolIf(ref b, ref t, ref f) => match normalize(b) {
             BoolLit(true) => normalize(t),
             BoolLit(false) => normalize(f),
             b2 => BoolIf(bx(b2), bx(normalize(t)), bx(normalize(f))),
         },
-        &NaturalLit(n) => NaturalLit(n),
-        &NaturalPlus(ref x, ref y) => {
+        NaturalLit(n) => NaturalLit(n),
+        NaturalPlus(ref x, ref y) => {
             with_binop(NaturalPlus, Expr::natural_lit,
                        |xn, yn| NaturalLit(xn + yn),
                        normalize(x), normalize(y))
         }
-        &NaturalTimes(ref x, ref y) => {
+        NaturalTimes(ref x, ref y) => {
             with_binop(NaturalTimes, Expr::natural_lit,
                        |xn, yn| NaturalLit(xn * yn),
                        normalize(x), normalize(y))
         }
-        &IntegerLit(n) => IntegerLit(n),
-        &DoubleLit(n) => DoubleLit(n),
-        &TextLit(ref t) => TextLit(t.clone()),
-        &TextAppend(ref x, ref y) => {
+        IntegerLit(n) => IntegerLit(n),
+        DoubleLit(n) => DoubleLit(n),
+        TextLit(ref t) => TextLit(t.clone()),
+        TextAppend(ref x, ref y) => {
             with_binop(TextAppend, Expr::text_lit,
                        |xt, yt| TextLit(xt + &yt),
                        normalize(x), normalize(y))
         }
-        &ListLit(ref t, ref es) => {
+        ListLit(ref t, ref es) => {
             let t2  = normalize(t);
             let es2 = es.iter().map(normalize).collect();
             ListLit(bx(t2), es2)
         }
-        &OptionalLit(ref t, ref es) => {
+        OptionalLit(ref t, ref es) => {
             let t2  = normalize(t);
             let es2 = es.iter().map(normalize).collect();
             OptionalLit(bx(t2), es2)
         }
-        &Record(ref kts) => Record(map_record_value(kts, normalize)),
-        &RecordLit(ref kvs) => RecordLit(map_record_value(kvs, normalize)),
-        &Union(ref kts) => Union(map_record_value(kts, normalize)),
-        &UnionLit(k, ref v, ref kvs) => UnionLit(k, bx(normalize(v)), map_record_value(kvs, normalize)),
-        &Combine(ref _x0, ref _y0) => unimplemented!(),
-        &Merge(ref _x, ref _y, ref _t) => unimplemented!(),
-        &Field(ref r, x) => match normalize(r) {
+        Record(ref kts) => Record(map_record_value(kts, normalize)),
+        RecordLit(ref kvs) => RecordLit(map_record_value(kvs, normalize)),
+        Union(ref kts) => Union(map_record_value(kts, normalize)),
+        UnionLit(k, ref v, ref kvs) => UnionLit(k, bx(normalize(v)), map_record_value(kvs, normalize)),
+        Combine(ref _x0, ref _y0) => unimplemented!(),
+        Merge(ref _x, ref _y, ref _t) => unimplemented!(),
+        Field(ref r, x) => match normalize(r) {
             RecordLit(kvs) => match kvs.get(x) {
                 Some(r2) => normalize(r2),
                 None => Field(bx(RecordLit(map_record_value(&kvs, normalize))), x),
             },
             r2 => Field(bx(r2), x),
         },
-        &Note(_, ref e) => normalize(e),
-        &Embed(ref a) => Embed(a.clone()),
+        Note(_, ref e) => normalize(e),
+        Embed(ref a) => Embed(a.clone()),
     }
 }
 
diff --git a/src/lexer.rs b/src/lexer.rs
index 2a7e44b..bc96040 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -328,7 +328,7 @@ impl<'input> Iterator for Lexer<'input> {
         use nom::IResult::*;
         self.skip_comments_and_whitespace();
         let input = self.current_input();
-        if input.len() == 0 {
+        if input.is_empty() {
             return None;
         }
         match token(input) {
diff --git a/src/main.rs b/src/main.rs
index d4b541b..9f7e2e1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,7 +24,7 @@ const ERROR_STYLE: term_painter::Color = term_painter::Color::Red;
 const BOLD: term_painter::Attr = term_painter::Attr::Bold;
 
 fn print_error(message: &str, source: &str, start: usize, end: usize) {
-    let line_number = bytecount::count(source[..start].as_bytes(), '\n' as u8);
+    let line_number = bytecount::count(source[..start].as_bytes(), b'\n');
     let line_start = source[..start].rfind('\n').map(|i| i + 1).unwrap_or(0);
     let line_end = source[end..].find('\n').unwrap_or(0) + end;
     let context_prefix = &source[line_start..start];
@@ -76,7 +76,7 @@ fn main() {
         }
         Err(lalrpop_util::ParseError::UnrecognizedToken { token: Some((start, t, end)), expected: e }) => {
             print_error(&format!("Unrecognized token {:?}", t), &buffer, start, end);
-            if e.len() > 0 {
+            if !e.is_empty() {
                 println!("Expected {:?}", e);
             }
             return;
@@ -93,7 +93,7 @@ fn main() {
 
     let type_expr = match typecheck::type_of(&expr) {
         Err(e) => {
-            let explain = ::std::env::args().find(|s| s == "--explain").is_some();
+            let explain = ::std::env::args().any(|s| s == "--explain");
             if !explain {
                 term_painter::Color::BrightBlack.with(|| {
                     println!("Use \"dhall --explain\" for detailed errors");
diff --git a/src/typecheck.rs b/src/typecheck.rs
index 39caa7e..576b059 100644
--- a/src/typecheck.rs
+++ b/src/typecheck.rs
@@ -24,8 +24,8 @@ fn axiom<'i, S: Clone>(c: core::Const) -> Result<core::Const, TypeError<'i, S>>
 fn rule(a: core::Const, b: core::Const) -> Result<core::Const, ()> {
     match (a, b) {
         (Type, Kind) => Err(()),
-        (Type, Type) => Ok(Type),
         (Kind, Kind) => Ok(Kind),
+        (Type, Type) |
         (Kind, Type) => Ok(Type),
     }
 }
@@ -52,10 +52,10 @@ fn prop_equal<S, T>(eL0: &Expr<S, X>, eR0: &Expr<T, X>) -> bool
               T: Clone + ::std::fmt::Debug
     {
         match (el, er) {
-            (&Const(Type), &Const(Type)) => true,
+            (&Const(Type), &Const(Type)) |
             (&Const(Kind), &Const(Kind)) => true,
             (&Var(ref vL), &Var(ref vR)) => match_vars(vL, vR, &*ctx),
-            (&Pi(ref xL, ref tL, ref bL), &Pi(ref xR, ref tR, ref bR)) => {
+            (&Pi(xL, ref tL, ref bL), &Pi(xR, ref tR, ref bR)) => {
                 //ctx <- State.get
                 let eq1 = go(ctx, tL, tR);
                 if eq1 {
@@ -164,15 +164,15 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
                         -> Result<Expr<'i, S, X>, TypeError<'i, S>>
     where S: Clone + ::std::fmt::Debug + 'i
 {
-    match e {
-        &Const(c) => axiom(c).map(Const), //.map(Cow::Owned),
-        &Var(V(ref x, n)) => {
+    match *e {
+        Const(c) => axiom(c).map(Const), //.map(Cow::Owned),
+        Var(V(x, n)) => {
             ctx.lookup(x, n)
                 .cloned()
                 //.map(Cow::Borrowed)
-                .ok_or_else(|| TypeError::new(ctx, &e, UnboundVariable))
+                .ok_or_else(|| TypeError::new(ctx, e, UnboundVariable))
         }
-        &Lam(ref x, ref tA, ref b) => {
+        Lam(x, ref tA, ref b) => {
             let ctx2 = ctx.insert(x, (**tA).clone()).map(|e| core::shift(1, V(x, 0), e));
             let tB = type_with(&ctx2, b)?;
             let p = Pi(x, tA.clone(), bx(tB));
@@ -180,7 +180,7 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
             //Ok(Cow::Owned(p))
             Ok(p)
         }
-        &Pi(ref x, ref tA, ref tB) => {
+        Pi(x, ref tA, ref tB) => {
             let tA2 = normalize::<S, S, X>(&type_with(ctx, tA)?);
             let kA = match tA2 {
                 Const(k) => k,
@@ -199,7 +199,7 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
                 Ok(k) => Ok(Const(k)),
             }
         }
-        &App(ref f, ref a) => {
+        App(ref f, ref a) => {
             let tf = normalize(&type_with(ctx, f)?);
             let (x, tA, tB) = match tf {
                 Pi(x, tA, tB) => (x, tA, tB),
@@ -218,14 +218,14 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
                 Err(TypeError::new(ctx, e, TypeMismatch((**f).clone(), nf_A, (**a).clone(), nf_A2)))
             }
         }
-        &Let(ref f, ref mt, ref r, ref b) => {
+        Let(f, ref mt, ref r, ref b) => {
             let tR  = type_with(ctx, r)?;
             let ttR = normalize::<S, S, X>(&type_with(ctx, &tR)?);
             let kR  = match ttR {
                 Const(k) => k,
                 // Don't bother to provide a `let`-specific version of this error
                 // message because this should never happen anyway
-                _        => return Err(TypeError::new(ctx, &e, InvalidInputType(tR))),
+                _        => return Err(TypeError::new(ctx, e, InvalidInputType(tR))),
             };
 
             let ctx2 = ctx.insert(f, tR.clone());
@@ -235,24 +235,24 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
                 Const(k) => k,
                 // Don't bother to provide a `let`-specific version of this error
                 // message because this should never happen anyway
-                _        => return Err(TypeError::new(ctx, &e, InvalidOutputType(tB))),
+                _        => return Err(TypeError::new(ctx, e, InvalidOutputType(tB))),
             };
 
             if let Err(()) = rule(kR, kB) {
-                return Err(TypeError::new(ctx, &e, NoDependentLet(tR, tB)));
+                return Err(TypeError::new(ctx, e, NoDependentLet(tR, tB)));
             }
 
-            if let &Some(ref t) = mt {
+            if let Some(ref t) = *mt {
                 let nf_t  = normalize(t);
                 let nf_tR = normalize(&tR);
                 if !prop_equal(&nf_tR, &nf_t) {
-                    return Err(TypeError::new(ctx, &e, AnnotMismatch((**r).clone(), nf_t, nf_tR)));
+                    return Err(TypeError::new(ctx, e, AnnotMismatch((**r).clone(), nf_t, nf_tR)));
                 }
             }
 
             Ok(tB)
         }
-        &Annot(ref x, ref t) => {
+        Annot(ref x, ref t) => {
             // This is mainly just to check that `t` is not `Kind`
             let _ = type_with(ctx, t)?;
 
@@ -265,16 +265,16 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
                 Err(TypeError::new(ctx, e, AnnotMismatch((**x).clone(), nf_t, nf_t2)))
             }
         }
-        &BuiltinType(t) => Ok(match t {
+        BuiltinType(t) => Ok(match t {
             List | Optional => pi("_", Const(Type), Const(Type)),
             Bool | Natural | Integer | Double | Text => Const(Type),
         }),
-        &BoolLit(_) => Ok(BuiltinType(Bool)),
-        &BoolAnd(ref l, ref r) => op2_type(ctx, e, Bool, CantAnd, l, r),
-        &BoolOr(ref l, ref r) => op2_type(ctx, e, Bool, CantOr, l, r),
-        &BoolEQ(ref l, ref r) => op2_type(ctx, e, Bool, CantEQ, l, r),
-        &BoolNE(ref l, ref r) => op2_type(ctx, e, Bool, CantNE, l, r),
-        &BoolIf(ref x, ref y, ref z) => {
+        BoolLit(_) => Ok(BuiltinType(Bool)),
+        BoolAnd(ref l, ref r) => op2_type(ctx, e, Bool, CantAnd, l, r),
+        BoolOr(ref l, ref r) => op2_type(ctx, e, Bool, CantOr, l, r),
+        BoolEQ(ref l, ref r) => op2_type(ctx, e, Bool, CantEQ, l, r),
+        BoolNE(ref l, ref r) => op2_type(ctx, e, Bool, CantNE, l, r),
+        BoolIf(ref x, ref y, ref z) => {
             let tx = normalize(&type_with(ctx, x)?);
             match tx {
                 BuiltinType(Bool) => {}
@@ -299,28 +299,28 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
             }
             Ok(ty)
         }
-        &NaturalLit(_) => Ok(BuiltinType(Natural)),
-        &BuiltinValue(NaturalFold) =>
+        NaturalLit(_) => Ok(BuiltinType(Natural)),
+        BuiltinValue(NaturalFold) =>
             Ok(pi("_", Natural,
                 pi("natural", Const(Type),
                     pi("succ", pi("_", "natural", "natural"),
                         pi("zero", "natural", "natural"))))),
-        &BuiltinValue(NaturalBuild) =>
+        BuiltinValue(NaturalBuild) =>
             Ok(pi("_",
                 pi("natural", Const(Type),
                     pi("succ", pi("_", "natural", "natural"),
                         pi("zero", "natural", "natural"))),
                 Natural)),
-        &BuiltinValue(NaturalIsZero) => Ok(pi("_", Natural, Bool)),
-        &BuiltinValue(NaturalEven) => Ok(pi("_", Natural, Bool)),
-        &BuiltinValue(NaturalOdd) => Ok(pi("_", Natural, Bool)),
-        &NaturalPlus(ref l, ref r) => op2_type(ctx, e, Natural, CantAdd, l, r),
-        &NaturalTimes(ref l, ref r) => op2_type(ctx, e, Natural, CantMultiply, l, r),
-        &IntegerLit(_) => Ok(BuiltinType(Integer)),
-        &DoubleLit(_) => Ok(BuiltinType(Double)),
-        &TextLit(_) => Ok(BuiltinType(Text)),
-        &TextAppend(ref l, ref r) => op2_type(ctx, e, Text, CantTextAppend, l, r),
-        &ListLit(ref t, ref xs) => {
+        BuiltinValue(NaturalIsZero) |
+        BuiltinValue(NaturalEven) |
+        BuiltinValue(NaturalOdd) => Ok(pi("_", Natural, Bool)),
+        NaturalPlus(ref l, ref r) => op2_type(ctx, e, Natural, CantAdd, l, r),
+        NaturalTimes(ref l, ref r) => op2_type(ctx, e, Natural, CantMultiply, l, r),
+        IntegerLit(_) => Ok(BuiltinType(Integer)),
+        DoubleLit(_) => Ok(BuiltinType(Double)),
+        TextLit(_) => Ok(BuiltinType(Text)),
+        TextAppend(ref l, ref r) => op2_type(ctx, e, Text, CantTextAppend, l, r),
+        ListLit(ref t, ref xs) => {
             let s = normalize::<_, S, _>(&type_with(ctx, t)?);
             match s {
                 Const(Type) => {}
@@ -336,34 +336,33 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
             }
             Ok(App(bx(BuiltinType(List)), t.clone()))
         }
-        &BuiltinValue(ListBuild) =>
+        BuiltinValue(ListBuild) =>
             Ok(pi("a", Const(Type),
                 pi("_",
                     pi("list", Const(Type),
                         pi("cons", pi("_", "a", pi("_", "list", "list")),
                             pi("nil", "list", "list"))),
                     app(List, "a")))),
-        &BuiltinValue(ListFold) =>
+        BuiltinValue(ListFold) =>
             Ok(pi("a", Const(Type),
                 pi("_", app(List, "a"),
                     pi("list", Const(Type),
                         pi("cons", pi("_", "a", pi("_", "list", "list")),
                             pi("nil", "list", "list")))))),
-        &BuiltinValue(ListLength) =>
+        BuiltinValue(ListLength) =>
             Ok(pi("a", Const(Type), pi("_", app(List, "a"), Natural))),
-        &BuiltinValue(ListHead) =>
+        BuiltinValue(ListHead) |
+        BuiltinValue(ListLast) =>
             Ok(pi("a", Const(Type), pi("_", app(List, "a"), app(Optional, "a")))),
-        &BuiltinValue(ListLast) =>
-            Ok(pi("a", Const(Type), pi("_", app(List, "a"), app(Optional, "a")))),
-        &BuiltinValue(ListIndexed) => {
+        BuiltinValue(ListIndexed) => {
             let mut m = BTreeMap::new();
             m.insert("index", BuiltinType(Natural));
             m.insert("value", Expr::from("a"));
             Ok(pi("a", Const(Type), pi("_", app(List, "a"), app(List, Record(m)))))
         }
-        &BuiltinValue(ListReverse) =>
+        BuiltinValue(ListReverse) =>
             Ok(pi("a", Const(Type), pi("_", app(List, "a"), app(List, "a")))),
-        &OptionalLit(ref t, ref xs) => {
+        OptionalLit(ref t, ref xs) => {
             let s = normalize::<_, S, _>(&type_with(ctx, t)?);
             match s {
                 Const(Type) => {}
@@ -383,13 +382,13 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
             }
             Ok(App(bx(BuiltinType(Optional)), t.clone()))
         }
-        &BuiltinValue(OptionalFold) =>
+        BuiltinValue(OptionalFold) =>
             Ok(pi("a", Const(Type),
                 pi("_", app(Optional, "a"),
                     pi("optional", Const(Type),
                         pi("just", pi("_", "a", "optional"),
                             pi("nothing", "optional", "optional")))))),
-        &Record(ref kts) => {
+        Record(ref kts) => {
             for (k, t) in kts {
                 let s = normalize::<S, S, X>(&type_with(ctx, t)?);
                 match s {
@@ -399,7 +398,7 @@ pub fn type_with<'i, S>(ctx: &Context<'i, Expr<'i, S, X>>,
             }
             Ok(Const(Type))
         }
-        &RecordLit(ref kvs) => {
+        RecordLit(ref kvs) => {
             let kts = kvs.iter().map(|(&k, v)| {
                 let t = type_with(ctx, v)?;
                 let s = normalize::<S, S, X>(&type_with(ctx, &t)?);
@@ -492,10 +491,10 @@ type_with ctx e@(Merge kvsX kvsY t) = do
     mapM_ process (Data.Map.toList ktsY)
     return t
     */
-        &Field(ref r, x) => {
+        Field(ref r, x) => {
             let t = normalize(&type_with(ctx, r)?);
-            match &t {
-                &Record(ref kts) =>
+            match t {
+                Record(ref kts) =>
                     kts.get(x).cloned().ok_or_else(|| TypeError::new(ctx, e, MissingField(x.to_owned(), t.clone()))),
                 _ => Err(TypeError::new(ctx, e, NotARecord(x.to_owned(), (**r).clone(), t.clone()))),
             }
@@ -506,7 +505,7 @@ type_with ctx   (Note s e'       ) = case type_with ctx e' of
     Left (TypeError ctx2          e''  m) -> Left (TypeError ctx2 (Note s  e'') m)
     Right r                               -> Right r
 */
-        &Embed(p) => match p {},
+        Embed(p) => match p {},
         _ => panic!("Unimplemented typecheck case: {:?}", e),
     }
 }
@@ -587,12 +586,12 @@ impl<'i, S: Clone> TypeError<'i, S> {
 
 impl<'i, S: fmt::Debug> ::std::error::Error for TypeMessage<'i, S> {
     fn description(&self) -> &str {
-        match self {
-            &UnboundVariable => "Unbound variable",
-            &InvalidInputType(_) => "Invalid function input",
-            &InvalidOutputType(_) => "Invalid function output",
-            &NotAFunction(_, _) => "Not a function",
-            &TypeMismatch(_, _, _, _) => "Wrong type of function argument",
+        match *self {
+            UnboundVariable => "Unbound variable",
+            InvalidInputType(_) => "Invalid function input",
+            InvalidOutputType(_) => "Invalid function output",
+            NotAFunction(_, _) => "Not a function",
+            TypeMismatch(_, _, _, _) => "Wrong type of function argument",
             _ => "Unhandled error",
         }
     }
@@ -600,9 +599,9 @@ impl<'i, S: fmt::Debug> ::std::error::Error for TypeMessage<'i, S> {
 
 impl<'i, S> fmt::Display for TypeMessage<'i, S> {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        match self {
-            &UnboundVariable => f.write_str(include_str!("errors/UnboundVariable.txt")),
-            &TypeMismatch(ref e0, ref e1, ref e2, ref e3) => {
+        match *self {
+            UnboundVariable => f.write_str(include_str!("errors/UnboundVariable.txt")),
+            TypeMismatch(ref e0, ref e1, ref e2, ref e3) => {
                 let template = include_str!("errors/TypeMismatch.txt");
                 let s = template
                     .replace("$txt0", &format!("{}", e0))