diff --git a/exercises/accumulate/Cargo.toml b/exercises/accumulate/Cargo.toml
index 78fb17a54..1be1f7550 100644
--- a/exercises/accumulate/Cargo.toml
+++ b/exercises/accumulate/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "accumulate"
 version = "0.0.0"
 
diff --git a/exercises/accumulate/tests/accumulate.rs b/exercises/accumulate/tests/accumulate.rs
index a5350a5fb..4a74b1db0 100644
--- a/exercises/accumulate/tests/accumulate.rs
+++ b/exercises/accumulate/tests/accumulate.rs
@@ -59,11 +59,10 @@ fn mutating_closure() {
     let mut counter = 0;
     let input = vec![-2, 3, 4, -5];
     let expected = vec![2, 3, 4, 5];
-    let result = map(input,
-        |x: i64| {
-            counter += 1;
-            x.abs()
-        });
+    let result = map(input, |x: i64| {
+        counter += 1;
+        x.abs()
+    });
     assert_eq!(result, expected);
     assert_eq!(counter, 4);
 }
diff --git a/exercises/acronym/Cargo.toml b/exercises/acronym/Cargo.toml
index 3422b3dfb..d476fe177 100644
--- a/exercises/acronym/Cargo.toml
+++ b/exercises/acronym/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "acronym"
 version = "1.0.0"
 
diff --git a/exercises/acronym/tests/acronym.rs b/exercises/acronym/tests/acronym.rs
index aaca32d68..6bb0f2a89 100644
--- a/exercises/acronym/tests/acronym.rs
+++ b/exercises/acronym/tests/acronym.rs
@@ -1,4 +1,4 @@
-extern crate acronym;
+use acronym;
 
 #[test]
 fn empty() {
diff --git a/exercises/all-your-base/Cargo.toml b/exercises/all-your-base/Cargo.toml
index bd2692b2e..10e06c8c9 100644
--- a/exercises/all-your-base/Cargo.toml
+++ b/exercises/all-your-base/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "allyourbase"
 version = "1.0.0"
diff --git a/exercises/all-your-base/tests/all-your-base.rs b/exercises/all-your-base/tests/all-your-base.rs
index 3f0641a9a..4da0eed57 100644
--- a/exercises/all-your-base/tests/all-your-base.rs
+++ b/exercises/all-your-base/tests/all-your-base.rs
@@ -1,4 +1,4 @@
-extern crate allyourbase as ayb;
+use allyourbase as ayb;
 
 #[test]
 fn single_bit_one_to_decimal() {
diff --git a/exercises/allergies/Cargo.toml b/exercises/allergies/Cargo.toml
index 2fe84d31b..cef7ea1ab 100644
--- a/exercises/allergies/Cargo.toml
+++ b/exercises/allergies/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "allergies"
 version = "1.1.0"
 
diff --git a/exercises/allergies/tests/allergies.rs b/exercises/allergies/tests/allergies.rs
index 1cc830c3c..5bcee4bfc 100644
--- a/exercises/allergies/tests/allergies.rs
+++ b/exercises/allergies/tests/allergies.rs
@@ -1,5 +1,3 @@
-extern crate allergies;
-
 use allergies::*;
 
 fn compare_allergy_vectors(expected: &[Allergen], actual: &[Allergen]) {
diff --git a/exercises/alphametics/Cargo-example.toml b/exercises/alphametics/Cargo-example.toml
index ef339dd65..508924443 100644
--- a/exercises/alphametics/Cargo-example.toml
+++ b/exercises/alphametics/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "alphametics"
 version = "0.0.0"
 
diff --git a/exercises/alphametics/Cargo.toml b/exercises/alphametics/Cargo.toml
index c5d55d9ea..44deb8348 100644
--- a/exercises/alphametics/Cargo.toml
+++ b/exercises/alphametics/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "alphametics"
 version = "1.3.0"
diff --git a/exercises/alphametics/example.rs b/exercises/alphametics/example.rs
index a04af36e4..3c4403e92 100644
--- a/exercises/alphametics/example.rs
+++ b/exercises/alphametics/example.rs
@@ -10,12 +10,20 @@ use std::char;
 use std::collections::HashMap;
 use std::collections::HashSet;
 
-fn test_equation(coefficients: &HashMap<char, i64>, cant_be_zero: &HashSet<char>, substitutions: &HashMap<char, u8>) -> bool {
+fn test_equation(
+    coefficients: &HashMap<char, i64>,
+    cant_be_zero: &HashSet<char>,
+    substitutions: &HashMap<char, u8>,
+) -> bool {
     if cant_be_zero.iter().any(|d| substitutions[d] == 0) {
         return false;
     }
 
-    coefficients.iter().map(|(d, &coeff)| i64::from(substitutions[d]) * coeff).sum::<i64>() == 0
+    coefficients
+        .iter()
+        .map(|(d, &coeff)| i64::from(substitutions[d]) * coeff)
+        .sum::<i64>()
+        == 0
 }
 
 fn letter_coefficients(puzzle: &str) -> (HashMap<char, i64>, HashSet<char>) {
diff --git a/exercises/alphametics/tests/alphametics.rs b/exercises/alphametics/tests/alphametics.rs
index 4b52e0e60..e3f45d36e 100644
--- a/exercises/alphametics/tests/alphametics.rs
+++ b/exercises/alphametics/tests/alphametics.rs
@@ -1,4 +1,4 @@
-extern crate alphametics;
+use alphametics;
 use std::collections::HashMap;
 
 fn assert_alphametic_solution_eq(puzzle: &str, solution: &[(char, u8)]) {
@@ -29,7 +29,10 @@ fn test_leading_zero_solution_is_invalid() {
 #[test]
 #[ignore]
 fn puzzle_with_two_digits_final_carry() {
-    assert_alphametic_solution_eq("A + A + A + A + A + A + A + A + A + A + A + B == BCC", &[('A', 9), ('B', 1), ('C', 0)]);
+    assert_alphametic_solution_eq(
+        "A + A + A + A + A + A + A + A + A + A + A + B == BCC",
+        &[('A', 9), ('B', 1), ('C', 0)],
+    );
 }
 
 #[test]
diff --git a/exercises/anagram/Cargo.toml b/exercises/anagram/Cargo.toml
index e31a809e2..ea3013150 100644
--- a/exercises/anagram/Cargo.toml
+++ b/exercises/anagram/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "anagram"
 version = "0.0.0"
diff --git a/exercises/anagram/tests/anagram.rs b/exercises/anagram/tests/anagram.rs
index cdc318512..464157409 100644
--- a/exercises/anagram/tests/anagram.rs
+++ b/exercises/anagram/tests/anagram.rs
@@ -1,4 +1,4 @@
-extern crate anagram;
+use anagram;
 
 use std::collections::HashSet;
 use std::iter::FromIterator;
diff --git a/exercises/armstrong-numbers/Cargo.toml b/exercises/armstrong-numbers/Cargo.toml
index f94476a90..c27b4d74d 100644
--- a/exercises/armstrong-numbers/Cargo.toml
+++ b/exercises/armstrong-numbers/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "armstrong_numbers"
 version = "1.0.0"
diff --git a/exercises/armstrong-numbers/example.rs b/exercises/armstrong-numbers/example.rs
index bf0459296..baa37f282 100644
--- a/exercises/armstrong-numbers/example.rs
+++ b/exercises/armstrong-numbers/example.rs
@@ -3,5 +3,6 @@ pub fn is_armstrong_number(num: u32) -> bool {
     let l = s.len();
     s.chars()
         .map(|c| c.to_digit(10).unwrap().pow(l as u32))
-        .sum::<u32>() == num
+        .sum::<u32>()
+        == num
 }
diff --git a/exercises/armstrong-numbers/tests/armstrong-numbers.rs b/exercises/armstrong-numbers/tests/armstrong-numbers.rs
index fd686d7d4..a785a14ca 100644
--- a/exercises/armstrong-numbers/tests/armstrong-numbers.rs
+++ b/exercises/armstrong-numbers/tests/armstrong-numbers.rs
@@ -1,4 +1,3 @@
-extern crate armstrong_numbers;
 use armstrong_numbers::*;
 
 #[test]
diff --git a/exercises/atbash-cipher/Cargo.toml b/exercises/atbash-cipher/Cargo.toml
index ec9f84135..d43249383 100644
--- a/exercises/atbash-cipher/Cargo.toml
+++ b/exercises/atbash-cipher/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "atbash-cipher"
 version = "1.1.0"
diff --git a/exercises/atbash-cipher/tests/atbash-cipher.rs b/exercises/atbash-cipher/tests/atbash-cipher.rs
index 31f04da74..f53c0daf9 100644
--- a/exercises/atbash-cipher/tests/atbash-cipher.rs
+++ b/exercises/atbash-cipher/tests/atbash-cipher.rs
@@ -1,4 +1,4 @@
-extern crate atbash_cipher as cipher;
+use atbash_cipher as cipher;
 
 #[test]
 fn test_encode_yes() {
diff --git a/exercises/beer-song/Cargo.toml b/exercises/beer-song/Cargo.toml
index 2618b6cc1..e85b7961d 100644
--- a/exercises/beer-song/Cargo.toml
+++ b/exercises/beer-song/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "beer-song"
 version = "0.0.0"
diff --git a/exercises/beer-song/tests/beer-song.rs b/exercises/beer-song/tests/beer-song.rs
index 1fddd3700..d5daaf363 100644
--- a/exercises/beer-song/tests/beer-song.rs
+++ b/exercises/beer-song/tests/beer-song.rs
@@ -1,4 +1,4 @@
-extern crate beer_song as beer;
+use beer_song as beer;
 
 #[test]
 fn test_verse_0() {
diff --git a/exercises/binary-search/Cargo.toml b/exercises/binary-search/Cargo.toml
index fb4e2dc1f..aeab7a084 100644
--- a/exercises/binary-search/Cargo.toml
+++ b/exercises/binary-search/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "binary-search"
 version = "1.3.0"
 
diff --git a/exercises/binary-search/tests/binary-search.rs b/exercises/binary-search/tests/binary-search.rs
index f9c2e496e..d6f0bc524 100644
--- a/exercises/binary-search/tests/binary-search.rs
+++ b/exercises/binary-search/tests/binary-search.rs
@@ -1,5 +1,3 @@
-extern crate binary_search;
-
 use binary_search::find;
 
 #[test]
diff --git a/exercises/bob/Cargo.toml b/exercises/bob/Cargo.toml
index 967acd20b..1483b9ad9 100644
--- a/exercises/bob/Cargo.toml
+++ b/exercises/bob/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "bob"
 version = "1.4.0"
diff --git a/exercises/bob/tests/bob.rs b/exercises/bob/tests/bob.rs
index 9de4533a3..db45861e8 100644
--- a/exercises/bob/tests/bob.rs
+++ b/exercises/bob/tests/bob.rs
@@ -1,4 +1,4 @@
-extern crate bob;
+use bob;
 
 fn process_response_case(phrase: &str, expected_response: &str) {
     assert_eq!(bob::reply(phrase), expected_response);
diff --git a/exercises/book-store/Cargo-example.toml b/exercises/book-store/Cargo-example.toml
index 2683bc5f4..5046bd4b7 100644
--- a/exercises/book-store/Cargo-example.toml
+++ b/exercises/book-store/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "book_store"
 version = "1.3.0"
 
diff --git a/exercises/book-store/Cargo.toml b/exercises/book-store/Cargo.toml
index 2683bc5f4..5046bd4b7 100644
--- a/exercises/book-store/Cargo.toml
+++ b/exercises/book-store/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "book_store"
 version = "1.3.0"
 
diff --git a/exercises/book-store/example.rs b/exercises/book-store/example.rs
index 228272dfa..2c709f6b0 100644
--- a/exercises/book-store/example.rs
+++ b/exercises/book-store/example.rs
@@ -25,13 +25,16 @@ impl Group {
     }
 
     fn price(&self) -> Price {
-        (self.0.borrow().len() as Price) * BOOK_PRICE * match self.0.borrow().len() {
-            2 => 95,
-            3 => 90,
-            4 => 80,
-            5 => 75,
-            _ => 100,
-        } / 100
+        (self.0.borrow().len() as Price)
+            * BOOK_PRICE
+            * match self.0.borrow().len() {
+                2 => 95,
+                3 => 90,
+                4 => 80,
+                5 => 75,
+                _ => 100,
+            }
+            / 100
     }
 }
 
diff --git a/exercises/book-store/tests/book-store.rs b/exercises/book-store/tests/book-store.rs
index b506c7818..8675e6903 100644
--- a/exercises/book-store/tests/book-store.rs
+++ b/exercises/book-store/tests/book-store.rs
@@ -5,7 +5,6 @@
 //! [script]: https://github.com/exercism/rust/blob/master/bin/init_exercise.py
 //! [canonical-data]: https://raw.githubusercontent.com/exercism/problem-specifications/master/exercises/book-store/canonical_data.json
 
-extern crate book_store;
 use book_store::*;
 
 /// Process a single test case for the property `total`
diff --git a/exercises/bowling/Cargo.toml b/exercises/bowling/Cargo.toml
index 3ef65f2ad..b14350ea8 100644
--- a/exercises/bowling/Cargo.toml
+++ b/exercises/bowling/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "bowling"
 version = "1.2.0"
diff --git a/exercises/bowling/tests/bowling.rs b/exercises/bowling/tests/bowling.rs
index fb628d5a7..77a4e876b 100644
--- a/exercises/bowling/tests/bowling.rs
+++ b/exercises/bowling/tests/bowling.rs
@@ -1,5 +1,3 @@
-extern crate bowling;
-
 use bowling::*;
 
 #[test]
diff --git a/exercises/bracket-push/Cargo.toml b/exercises/bracket-push/Cargo.toml
index 9b156f1f7..73d23780e 100644
--- a/exercises/bracket-push/Cargo.toml
+++ b/exercises/bracket-push/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "bracket-push"
 version = "1.5.0"
diff --git a/exercises/bracket-push/example.rs b/exercises/bracket-push/example.rs
index 5d2e0f732..44310d294 100644
--- a/exercises/bracket-push/example.rs
+++ b/exercises/bracket-push/example.rs
@@ -57,7 +57,8 @@ impl From<Vec<(char, char)>> for MatchingBrackets {
 
 impl MatchingBrackets {
     fn contains(&self, other: &char) -> bool {
-        let known = self.collection
+        let known = self
+            .collection
             .keys()
             .chain(self.collection.values())
             .collect::<Vec<_>>();
diff --git a/exercises/bracket-push/src/lib.rs b/exercises/bracket-push/src/lib.rs
index f7004c16f..1241a971a 100644
--- a/exercises/bracket-push/src/lib.rs
+++ b/exercises/bracket-push/src/lib.rs
@@ -1,3 +1,6 @@
 pub fn brackets_are_balanced(string: &str) -> bool {
-    unimplemented!("Check if the string \"{}\" contains balanced brackets", string);
+    unimplemented!(
+        "Check if the string \"{}\" contains balanced brackets",
+        string
+    );
 }
diff --git a/exercises/bracket-push/tests/bracket-push.rs b/exercises/bracket-push/tests/bracket-push.rs
index dfd6d211b..c9df5f18a 100644
--- a/exercises/bracket-push/tests/bracket-push.rs
+++ b/exercises/bracket-push/tests/bracket-push.rs
@@ -1,5 +1,3 @@
-extern crate bracket_push;
-
 use bracket_push::brackets_are_balanced;
 
 #[test]
diff --git a/exercises/circular-buffer/Cargo.toml b/exercises/circular-buffer/Cargo.toml
index b21eefc8c..eb493f4d0 100644
--- a/exercises/circular-buffer/Cargo.toml
+++ b/exercises/circular-buffer/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "circular-buffer"
 version = "1.1.0"
diff --git a/exercises/circular-buffer/tests/circular-buffer.rs b/exercises/circular-buffer/tests/circular-buffer.rs
index 449806a66..1e73ad865 100644
--- a/exercises/circular-buffer/tests/circular-buffer.rs
+++ b/exercises/circular-buffer/tests/circular-buffer.rs
@@ -1,4 +1,3 @@
-extern crate circular_buffer;
 use circular_buffer::{CircularBuffer, Error};
 
 #[test]
diff --git a/exercises/clock/Cargo.toml b/exercises/clock/Cargo.toml
index 26884e177..376e7f1e5 100644
--- a/exercises/clock/Cargo.toml
+++ b/exercises/clock/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "clock"
 version = "2.4.0"
 
diff --git a/exercises/collatz-conjecture/Cargo.toml b/exercises/collatz-conjecture/Cargo.toml
index 5b905f512..e102b3388 100644
--- a/exercises/collatz-conjecture/Cargo.toml
+++ b/exercises/collatz-conjecture/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "collatz_conjecture"
 version = "1.2.1"
diff --git a/exercises/collatz-conjecture/tests/collatz-conjecture.rs b/exercises/collatz-conjecture/tests/collatz-conjecture.rs
index 86ff0ed2b..f98c5c619 100644
--- a/exercises/collatz-conjecture/tests/collatz-conjecture.rs
+++ b/exercises/collatz-conjecture/tests/collatz-conjecture.rs
@@ -1,5 +1,3 @@
-extern crate collatz_conjecture;
-
 use collatz_conjecture::*;
 
 #[test]
diff --git a/exercises/crypto-square/Cargo-example.toml b/exercises/crypto-square/Cargo-example.toml
index c2ceff4b7..985096923 100644
--- a/exercises/crypto-square/Cargo-example.toml
+++ b/exercises/crypto-square/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "crypto-square"
 version = "0.1.0"
 
diff --git a/exercises/crypto-square/Cargo.toml b/exercises/crypto-square/Cargo.toml
index 1b96557b6..f19592610 100644
--- a/exercises/crypto-square/Cargo.toml
+++ b/exercises/crypto-square/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "crypto-square"
 version = "0.1.0"
 
diff --git a/exercises/crypto-square/tests/crypto-square.rs b/exercises/crypto-square/tests/crypto-square.rs
index 9ad55533d..ba65c2e43 100644
--- a/exercises/crypto-square/tests/crypto-square.rs
+++ b/exercises/crypto-square/tests/crypto-square.rs
@@ -1,4 +1,3 @@
-extern crate crypto_square;
 use crypto_square::encrypt;
 
 fn test(input: &str, output: &str) {
diff --git a/exercises/custom-set/Cargo.toml b/exercises/custom-set/Cargo.toml
index 1cc4ef159..2f5fc29bf 100644
--- a/exercises/custom-set/Cargo.toml
+++ b/exercises/custom-set/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "custom-set"
 version = "1.0.1"
diff --git a/exercises/custom-set/example.rs b/exercises/custom-set/example.rs
index ecab76b68..a3d0c1099 100644
--- a/exercises/custom-set/example.rs
+++ b/exercises/custom-set/example.rs
@@ -44,26 +44,35 @@ impl<T: Ord + Clone> CustomSet<T> {
     }
 
     pub fn intersection(&self, other: &Self) -> CustomSet<T> {
-        CustomSet::new(&self.collection
-            .iter()
-            .cloned()
-            .filter(|c| other.contains(c))
-            .collect::<Vec<_>>())
+        CustomSet::new(
+            &self
+                .collection
+                .iter()
+                .cloned()
+                .filter(|c| other.contains(c))
+                .collect::<Vec<_>>(),
+        )
     }
 
     pub fn union(&self, other: &Self) -> CustomSet<T> {
-        CustomSet::new(&self.collection
-            .iter()
-            .cloned()
-            .chain(other.collection.iter().cloned())
-            .collect::<Vec<_>>())
+        CustomSet::new(
+            &self
+                .collection
+                .iter()
+                .cloned()
+                .chain(other.collection.iter().cloned())
+                .collect::<Vec<_>>(),
+        )
     }
 
     pub fn difference(&self, other: &Self) -> CustomSet<T> {
-        CustomSet::new(&self.collection
-            .iter()
-            .cloned()
-            .filter(|c| !other.contains(c))
-            .collect::<Vec<_>>())
+        CustomSet::new(
+            &self
+                .collection
+                .iter()
+                .cloned()
+                .filter(|c| !other.contains(c))
+                .collect::<Vec<_>>(),
+        )
     }
 }
diff --git a/exercises/decimal/Cargo-example.toml b/exercises/decimal/Cargo-example.toml
index 7e7562af4..3423c8071 100644
--- a/exercises/decimal/Cargo-example.toml
+++ b/exercises/decimal/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "decimal"
 version = "0.1.0"
 
diff --git a/exercises/decimal/Cargo.toml b/exercises/decimal/Cargo.toml
index 75189e485..44f62de2d 100644
--- a/exercises/decimal/Cargo.toml
+++ b/exercises/decimal/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "decimal"
 version = "0.1.0"
 
diff --git a/exercises/decimal/example.rs b/exercises/decimal/example.rs
index 262c69481..4bae40e7f 100644
--- a/exercises/decimal/example.rs
+++ b/exercises/decimal/example.rs
@@ -87,7 +87,8 @@ impl Decimal {
     ///
     /// This reduces the decimal index, so that the raw values are easier to parse
     fn reduce(&mut self) {
-        let extra_zeroes = self.digits
+        let extra_zeroes = self
+            .digits
             .to_string() // produce a decimal representation
             .chars()
             .rev() // trailing values
diff --git a/exercises/diamond/Cargo.toml b/exercises/diamond/Cargo.toml
index b552ed35e..b3df19d05 100644
--- a/exercises/diamond/Cargo.toml
+++ b/exercises/diamond/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "diamond"
 version = "1.1.0"
 
diff --git a/exercises/diamond/tests/diamond.rs b/exercises/diamond/tests/diamond.rs
index 74ac9893c..c3d699bdc 100644
--- a/exercises/diamond/tests/diamond.rs
+++ b/exercises/diamond/tests/diamond.rs
@@ -1,4 +1,4 @@
-extern crate diamond;
+
 use diamond::*;
 
 #[test]
diff --git a/exercises/difference-of-squares/Cargo.toml b/exercises/difference-of-squares/Cargo.toml
index 5e7cda6c7..41e2b29db 100644
--- a/exercises/difference-of-squares/Cargo.toml
+++ b/exercises/difference-of-squares/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "difference-of-squares"
 version = "1.2.0"
diff --git a/exercises/difference-of-squares/tests/difference-of-square.rs b/exercises/difference-of-squares/tests/difference-of-square.rs
index b6fa4a005..7cc2caa42 100644
--- a/exercises/difference-of-squares/tests/difference-of-square.rs
+++ b/exercises/difference-of-squares/tests/difference-of-square.rs
@@ -1,4 +1,4 @@
-extern crate difference_of_squares as squares;
+use difference_of_squares as squares;
 
 #[test]
 fn test_square_of_sum_1() {
diff --git a/exercises/diffie-hellman/Cargo-example.toml b/exercises/diffie-hellman/Cargo-example.toml
index 80bd029ea..7fc0123f5 100644
--- a/exercises/diffie-hellman/Cargo-example.toml
+++ b/exercises/diffie-hellman/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "diffie-hellman"
 version = "0.1.0"
 
diff --git a/exercises/diffie-hellman/Cargo.toml b/exercises/diffie-hellman/Cargo.toml
index a6d2b492f..8c1d9df72 100644
--- a/exercises/diffie-hellman/Cargo.toml
+++ b/exercises/diffie-hellman/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "diffie-hellman"
 version = "0.1.0"
 
diff --git a/exercises/diffie-hellman/tests/diffie-hellman.rs b/exercises/diffie-hellman/tests/diffie-hellman.rs
index 0f4109df5..f3015998c 100644
--- a/exercises/diffie-hellman/tests/diffie-hellman.rs
+++ b/exercises/diffie-hellman/tests/diffie-hellman.rs
@@ -1,5 +1,3 @@
-extern crate diffie_hellman;
-
 use diffie_hellman::*;
 
 #[test]
diff --git a/exercises/dominoes/Cargo.toml b/exercises/dominoes/Cargo.toml
index fa56a612b..eed6c1911 100644
--- a/exercises/dominoes/Cargo.toml
+++ b/exercises/dominoes/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "dominoes"
 version = "2.1.0"
diff --git a/exercises/dominoes/example.rs b/exercises/dominoes/example.rs
index 34e5aef67..72de2d4f3 100644
--- a/exercises/dominoes/example.rs
+++ b/exercises/dominoes/example.rs
@@ -70,11 +70,13 @@ impl AvailabilityTable {
 pub fn chain(dominoes: &[Domino]) -> Option<Vec<Domino>> {
     match dominoes.len() {
         0 => Some(vec![]),
-        1 => if dominoes[0].0 == dominoes[0].1 {
-            Some(vec![dominoes[0]])
-        } else {
-            None
-        },
+        1 => {
+            if dominoes[0].0 == dominoes[0].1 {
+                Some(vec![dominoes[0]])
+            } else {
+                None
+            }
+        }
         _ => {
             // First check if the total number of each amount of dots is even, if not it's not
             // possible to complete a cycle. This follows from that it's an Eulerian path.
diff --git a/exercises/dominoes/tests/dominoes.rs b/exercises/dominoes/tests/dominoes.rs
index f6d0c8d9d..fa882078c 100644
--- a/exercises/dominoes/tests/dominoes.rs
+++ b/exercises/dominoes/tests/dominoes.rs
@@ -1,6 +1,6 @@
-extern crate dominoes;
+use dominoes;
 
-use CheckResult::*;
+use crate::CheckResult::*;
 
 type Domino = (u8, u8);
 
@@ -33,7 +33,10 @@ fn check(input: &[Domino]) -> CheckResult {
         return Correct;
     }
 
-    let mut output_sorted = output.iter().map(|&d| normalize(d)).collect::<Vec<Domino>>();
+    let mut output_sorted = output
+        .iter()
+        .map(|&d| normalize(d))
+        .collect::<Vec<Domino>>();
     output_sorted.sort();
     let mut input_sorted = input.iter().map(|&d| normalize(d)).collect::<Vec<Domino>>();
     input_sorted.sort();
diff --git a/exercises/dot-dsl/Cargo.toml b/exercises/dot-dsl/Cargo.toml
index 57a458b0a..3da0d6721 100644
--- a/exercises/dot-dsl/Cargo.toml
+++ b/exercises/dot-dsl/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "dot-dsl"
 version = "0.1.0"
 
diff --git a/exercises/dot-dsl/tests/dot-dsl.rs b/exercises/dot-dsl/tests/dot-dsl.rs
index cce5a389d..0f15d7150 100644
--- a/exercises/dot-dsl/tests/dot-dsl.rs
+++ b/exercises/dot-dsl/tests/dot-dsl.rs
@@ -2,9 +2,9 @@
 extern crate maplit;
 extern crate dot_dsl;
 
-use dot_dsl::graph::Graph;
 use dot_dsl::graph::graph_items::edge::Edge;
 use dot_dsl::graph::graph_items::node::Node;
+use dot_dsl::graph::Graph;
 
 #[test]
 fn test_empty_graph() {
@@ -67,7 +67,7 @@ fn test_graph_with_one_edge() {
 fn test_graph_with_one_attribute() {
     let graph = Graph::new().with_attrs(&[("foo", "1")]);
 
-    let expected_attrs = hashmap!{
+    let expected_attrs = hashmap! {
         "foo".to_string() => "1".to_string(),
     };
 
@@ -129,11 +129,13 @@ fn test_graph_with_attributes() {
 #[ignore]
 fn test_graph_stores_attributes() {
     let attributes = [("foo", "bar"), ("bat", "baz"), ("bim", "bef")];
-    let graph = Graph::new().with_nodes(&['a', 'b', 'c']
-        .iter()
-        .enumerate()
-        .map(|(i, n)| Node::new(&n.to_string()).with_attrs(&attributes[i..i + 1]))
-        .collect::<Vec<_>>());
+    let graph = Graph::new().with_nodes(
+        &['a', 'b', 'c']
+            .iter()
+            .enumerate()
+            .map(|(i, n)| Node::new(&n.to_string()).with_attrs(&attributes[i..i + 1]))
+            .collect::<Vec<_>>(),
+    );
 
     assert_eq!(
         graph
diff --git a/exercises/etl/Cargo.toml b/exercises/etl/Cargo.toml
index ce735e012..e94ff4da1 100644
--- a/exercises/etl/Cargo.toml
+++ b/exercises/etl/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "etl"
 version = "1.0.0"
diff --git a/exercises/etl/tests/etl.rs b/exercises/etl/tests/etl.rs
index 67d1527de..ff28dcfb1 100644
--- a/exercises/etl/tests/etl.rs
+++ b/exercises/etl/tests/etl.rs
@@ -1,4 +1,4 @@
-extern crate etl;
+use etl;
 
 use std::collections::BTreeMap;
 
diff --git a/exercises/forth/Cargo.toml b/exercises/forth/Cargo.toml
index a56ae8974..912e8e5c0 100644
--- a/exercises/forth/Cargo.toml
+++ b/exercises/forth/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "forth"
 version = "1.7.0"
diff --git a/exercises/forth/example.rs b/exercises/forth/example.rs
index b32e57aa9..9a14b518e 100644
--- a/exercises/forth/example.rs
+++ b/exercises/forth/example.rs
@@ -40,8 +40,9 @@ impl FromStr for Term {
             ":" => Ok(Term::StartDefinition),
             ";" => Ok(Term::EndDefinition),
             _ => Err(()),
-        }.or_else(|_| Value::from_str(s).map(Term::Number))
-            .or_else(|_| Ok(Term::Word(s.to_ascii_lowercase())))
+        }
+        .or_else(|_| Value::from_str(s).map(Term::Number))
+        .or_else(|_| Ok(Term::Word(s.to_ascii_lowercase())))
     }
 }
 
@@ -98,9 +99,11 @@ impl Forth {
             "/" => self.bin_op(|(a, b)| a.checked_div(b).ok_or(Error::DivisionByZero)),
             "dup" => self.pop().and_then(|a| self.push(a).and(self.push(a))),
             "drop" => self.pop().and(Forth::ok()),
-            "swap" => self.pop_two()
+            "swap" => self
+                .pop_two()
                 .and_then(|(a, b)| self.push(b).and(self.push(a))),
-            "over" => self.pop_two()
+            "over" => self
+                .pop_two()
                 .and_then(|(a, b)| self.push(a).and(self.push(b)).and(self.push(a))),
             _ => Err(Error::UnknownWord),
         }
@@ -151,11 +154,13 @@ impl Forth {
         for t in code.iter() {
             match t {
                 Term::Number(_) => resolved_def.push_back(t.clone()),
-                Term::Word(s) => if let Some(cs) = self.defs.get(s) {
-                    resolved_def.append(&mut cs.clone());
-                } else {
-                    resolved_def.push_back(t.clone());
-                },
+                Term::Word(s) => {
+                    if let Some(cs) = self.defs.get(s) {
+                        resolved_def.append(&mut cs.clone());
+                    } else {
+                        resolved_def.push_back(t.clone());
+                    }
+                }
                 _ => unimplemented!("not even sure a definition in a definition is valid Forth"),
             }
         }
diff --git a/exercises/forth/tests/forth.rs b/exercises/forth/tests/forth.rs
index 8f91533fb..dcf99aae6 100644
--- a/exercises/forth/tests/forth.rs
+++ b/exercises/forth/tests/forth.rs
@@ -1,5 +1,3 @@
-extern crate forth;
-
 use forth::{Error, Forth, Value};
 
 #[test]
diff --git a/exercises/gigasecond/Cargo.toml b/exercises/gigasecond/Cargo.toml
index 42eb3fb3c..857600c8b 100644
--- a/exercises/gigasecond/Cargo.toml
+++ b/exercises/gigasecond/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "gigasecond"
 version = "1.1.0"
 
diff --git a/exercises/gigasecond/src/lib.rs b/exercises/gigasecond/src/lib.rs
index fc2f2c180..8b5673093 100644
--- a/exercises/gigasecond/src/lib.rs
+++ b/exercises/gigasecond/src/lib.rs
@@ -1,4 +1,3 @@
-extern crate chrono;
 use chrono::{DateTime, Utc};
 
 // Returns a Utc DateTime one billion seconds after start.
diff --git a/exercises/gigasecond/tests/gigasecond.rs b/exercises/gigasecond/tests/gigasecond.rs
index 266ad8358..b42c35a06 100644
--- a/exercises/gigasecond/tests/gigasecond.rs
+++ b/exercises/gigasecond/tests/gigasecond.rs
@@ -1,5 +1,5 @@
-extern crate gigasecond;
-extern crate chrono;
+use gigasecond;
+
 use chrono::{TimeZone, Utc};
 
 #[test]
diff --git a/exercises/grade-school/Cargo.toml b/exercises/grade-school/Cargo.toml
index 31a2b1a9f..43ad34405 100644
--- a/exercises/grade-school/Cargo.toml
+++ b/exercises/grade-school/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "grade-school"
 version = "0.0.0"
diff --git a/exercises/grade-school/tests/grade-school.rs b/exercises/grade-school/tests/grade-school.rs
index bb27b8259..65146e15d 100644
--- a/exercises/grade-school/tests/grade-school.rs
+++ b/exercises/grade-school/tests/grade-school.rs
@@ -1,4 +1,4 @@
-extern crate grade_school as school;
+use grade_school as school;
 
 fn some_strings(v: &[&str]) -> Option<Vec<String>> {
     Some(v.iter().map(|s| s.to_string()).collect())
diff --git a/exercises/grains/Cargo.toml b/exercises/grains/Cargo.toml
index 3fa534346..6bf141e72 100644
--- a/exercises/grains/Cargo.toml
+++ b/exercises/grains/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "grains"
 version = "1.2.0"
diff --git a/exercises/grains/tests/grains.rs b/exercises/grains/tests/grains.rs
index 61a9c603a..25c990dd9 100644
--- a/exercises/grains/tests/grains.rs
+++ b/exercises/grains/tests/grains.rs
@@ -1,4 +1,4 @@
-extern crate grains;
+use grains;
 
 #[test]
 fn square_one() {
diff --git a/exercises/grep/Cargo.toml b/exercises/grep/Cargo.toml
index 4bfad5589..ee945edf7 100644
--- a/exercises/grep/Cargo.toml
+++ b/exercises/grep/Cargo.toml
@@ -2,5 +2,6 @@
 failure = "0.1.1"
 
 [package]
+edition = "2018"
 name = "grep"
 version = "1.2.0"
diff --git a/exercises/grep/src/lib.rs b/exercises/grep/src/lib.rs
index f0b8f02da..20e7a2af8 100644
--- a/exercises/grep/src/lib.rs
+++ b/exercises/grep/src/lib.rs
@@ -1,5 +1,3 @@
-extern crate failure;
-
 use failure::Error;
 
 /// While using raw slice of str to handle flags is convenient,
diff --git a/exercises/grep/tests/grep.rs b/exercises/grep/tests/grep.rs
index 0476d0351..a5485b076 100644
--- a/exercises/grep/tests/grep.rs
+++ b/exercises/grep/tests/grep.rs
@@ -1,5 +1,3 @@
-extern crate grep;
-
 use grep::{grep, Flags};
 
 use std::fs;
@@ -72,7 +70,8 @@ impl<'a> Fixture<'a> {
                 } else {
                     (file_name, IN_THE_WHITE_NIGHT_CONTENT)
                 }
-            }).collect::<Vec<(&str, &str)>>();
+            })
+            .collect::<Vec<(&str, &str)>>();
 
         set_up_files(&file_name_content_pairs);
     }
diff --git a/exercises/hamming/Cargo.toml b/exercises/hamming/Cargo.toml
index e8c13af23..efb643e20 100644
--- a/exercises/hamming/Cargo.toml
+++ b/exercises/hamming/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "hamming"
 version = "2.1.1"
diff --git a/exercises/hamming/tests/hamming.rs b/exercises/hamming/tests/hamming.rs
index 523e40160..24e2637e3 100644
--- a/exercises/hamming/tests/hamming.rs
+++ b/exercises/hamming/tests/hamming.rs
@@ -1,4 +1,4 @@
-extern crate hamming;
+use hamming;
 
 fn process_distance_case(strand_pair: [&str; 2], expected_distance: Option<usize>) {
     assert_eq!(
diff --git a/exercises/hello-world/Cargo.toml b/exercises/hello-world/Cargo.toml
index 69311b8f5..4d9f8bb06 100644
--- a/exercises/hello-world/Cargo.toml
+++ b/exercises/hello-world/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "hello-world"
 version = "1.1.0"
diff --git a/exercises/hello-world/tests/hello-world.rs b/exercises/hello-world/tests/hello-world.rs
index 99a3c1561..c0d9536db 100644
--- a/exercises/hello-world/tests/hello-world.rs
+++ b/exercises/hello-world/tests/hello-world.rs
@@ -1,4 +1,4 @@
-extern crate hello_world;
+use hello_world;
 
 #[test]
 fn test_hello_world() {
diff --git a/exercises/hexadecimal/Cargo.toml b/exercises/hexadecimal/Cargo.toml
index 313084bc0..062e6a9a0 100644
--- a/exercises/hexadecimal/Cargo.toml
+++ b/exercises/hexadecimal/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "hexadecimal"
 version = "0.0.0"
diff --git a/exercises/isbn-verifier/Cargo.toml b/exercises/isbn-verifier/Cargo.toml
index 2fa438447..01a1e82af 100644
--- a/exercises/isbn-verifier/Cargo.toml
+++ b/exercises/isbn-verifier/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "isbn-verifier"
 version = "2.7.0"
diff --git a/exercises/isbn-verifier/tests/isbn-verifier.rs b/exercises/isbn-verifier/tests/isbn-verifier.rs
index 930f8dd02..ea381c0b9 100644
--- a/exercises/isbn-verifier/tests/isbn-verifier.rs
+++ b/exercises/isbn-verifier/tests/isbn-verifier.rs
@@ -1,5 +1,3 @@
-extern crate isbn_verifier;
-
 use isbn_verifier::is_valid_isbn;
 
 #[test]
diff --git a/exercises/isogram/Cargo.toml b/exercises/isogram/Cargo.toml
index 63f479d41..9841e7595 100644
--- a/exercises/isogram/Cargo.toml
+++ b/exercises/isogram/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "isogram"
 version = "1.3.0"
diff --git a/exercises/isogram/example.rs b/exercises/isogram/example.rs
index 2a32046d2..c475e7a3e 100644
--- a/exercises/isogram/example.rs
+++ b/exercises/isogram/example.rs
@@ -1,12 +1,13 @@
 pub fn check(word: &str) -> bool {
     // Filter all non-Alphabetic character out and collect them in a new String
-    let normalized_string: String = word.to_lowercase()
+    let normalized_string: String = word
+        .to_lowercase()
         .chars()
         .filter(|c| c.is_alphabetic())
         .collect();
 
     /* Find the char element from back and front and compare the index.
-       If it is the same unique char the index will be the same.*/
+    If it is the same unique char the index will be the same.*/
     let is_unique = |x: char, word: &str| word.find(x).unwrap() == word.rfind(x).unwrap();
 
     // Length should be the same if it is a isogram
diff --git a/exercises/isogram/tests/isogram.rs b/exercises/isogram/tests/isogram.rs
index c94d44922..932bd3cd4 100644
--- a/exercises/isogram/tests/isogram.rs
+++ b/exercises/isogram/tests/isogram.rs
@@ -1,5 +1,3 @@
-extern crate isogram;
-
 use isogram::check;
 
 #[test]
diff --git a/exercises/largest-series-product/Cargo.toml b/exercises/largest-series-product/Cargo.toml
index 37fd83a73..f03ff47ec 100644
--- a/exercises/largest-series-product/Cargo.toml
+++ b/exercises/largest-series-product/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "largest-series-product"
 version = "1.2.0"
diff --git a/exercises/largest-series-product/tests/largest-series-product.rs b/exercises/largest-series-product/tests/largest-series-product.rs
index 92781dc50..97ca0a6a9 100644
--- a/exercises/largest-series-product/tests/largest-series-product.rs
+++ b/exercises/largest-series-product/tests/largest-series-product.rs
@@ -1,5 +1,3 @@
-extern crate largest_series_product;
-
 use largest_series_product::*;
 
 #[test]
diff --git a/exercises/leap/Cargo.toml b/exercises/leap/Cargo.toml
index d96dc5de6..2e0adb3ed 100644
--- a/exercises/leap/Cargo.toml
+++ b/exercises/leap/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "leap"
 version = "1.4.0"
diff --git a/exercises/leap/tests/leap.rs b/exercises/leap/tests/leap.rs
index 097dd96e5..1198a9938 100644
--- a/exercises/leap/tests/leap.rs
+++ b/exercises/leap/tests/leap.rs
@@ -1,4 +1,4 @@
-extern crate leap;
+use leap;
 
 fn process_leapyear_case(year: u64, expected: bool) {
     assert_eq!(leap::is_leap_year(year), expected);
diff --git a/exercises/luhn-from/Cargo.toml b/exercises/luhn-from/Cargo.toml
index 8fdafb024..5e0bc0a83 100644
--- a/exercises/luhn-from/Cargo.toml
+++ b/exercises/luhn-from/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "luhn-from"
 version = "0.0.0"
diff --git a/exercises/luhn-from/example.rs b/exercises/luhn-from/example.rs
index 77bea10d5..1cfd286a7 100644
--- a/exercises/luhn-from/example.rs
+++ b/exercises/luhn-from/example.rs
@@ -15,7 +15,9 @@ impl Luhn {
             .enumerate()
             .map(|(index, digit)| if index % 2 == 0 { digit } else { digit * 2 })
             .map(|digit| if digit > 9 { digit - 9 } else { digit })
-            .sum::<u32>() % 10 == 0
+            .sum::<u32>()
+            % 10
+            == 0
     }
 }
 
diff --git a/exercises/luhn-trait/Cargo.toml b/exercises/luhn-trait/Cargo.toml
index e0bd9df67..c68f2e3f0 100644
--- a/exercises/luhn-trait/Cargo.toml
+++ b/exercises/luhn-trait/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "luhn-trait"
 version = "0.0.0"
diff --git a/exercises/luhn-trait/example.rs b/exercises/luhn-trait/example.rs
index b703231ff..ed71406fd 100644
--- a/exercises/luhn-trait/example.rs
+++ b/exercises/luhn-trait/example.rs
@@ -14,7 +14,9 @@ impl Luhn for String {
             .enumerate()
             .map(|(index, digit)| if index % 2 == 0 { digit } else { digit * 2 })
             .map(|digit| if digit > 9 { digit - 9 } else { digit })
-            .sum::<u32>() % 10 == 0
+            .sum::<u32>()
+            % 10
+            == 0
     }
 }
 
diff --git a/exercises/luhn/Cargo.toml b/exercises/luhn/Cargo.toml
index 75c0ccb51..af784656b 100644
--- a/exercises/luhn/Cargo.toml
+++ b/exercises/luhn/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "luhn"
 version = "1.3.0"
diff --git a/exercises/luhn/example.rs b/exercises/luhn/example.rs
index ce52adf61..4308887d6 100644
--- a/exercises/luhn/example.rs
+++ b/exercises/luhn/example.rs
@@ -12,5 +12,7 @@ pub fn is_valid(candidate: &str) -> bool {
         .enumerate()
         .map(|(index, digit)| if index % 2 == 0 { digit } else { digit * 2 })
         .map(|digit| if digit > 9 { digit - 9 } else { digit })
-        .sum::<u32>() % 10 == 0
+        .sum::<u32>()
+        % 10
+        == 0
 }
diff --git a/exercises/luhn/tests/luhn.rs b/exercises/luhn/tests/luhn.rs
index 061b9c90a..0915cdf73 100644
--- a/exercises/luhn/tests/luhn.rs
+++ b/exercises/luhn/tests/luhn.rs
@@ -1,5 +1,3 @@
-extern crate luhn;
-
 use luhn::*;
 
 #[test]
diff --git a/exercises/macros/Cargo.toml b/exercises/macros/Cargo.toml
index 8e58411d0..b7d10d7b2 100644
--- a/exercises/macros/Cargo.toml
+++ b/exercises/macros/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "macros"
 version = "0.1.0"
 
diff --git a/exercises/minesweeper/Cargo.toml b/exercises/minesweeper/Cargo.toml
index fe1f5c79a..acb6b8e6f 100644
--- a/exercises/minesweeper/Cargo.toml
+++ b/exercises/minesweeper/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "minesweeper"
 version = "1.1.0"
diff --git a/exercises/minesweeper/tests/minesweeper.rs b/exercises/minesweeper/tests/minesweeper.rs
index 09fc121a2..632911263 100644
--- a/exercises/minesweeper/tests/minesweeper.rs
+++ b/exercises/minesweeper/tests/minesweeper.rs
@@ -1,4 +1,4 @@
-extern crate minesweeper;
+
 
 use minesweeper::annotate;
 
diff --git a/exercises/nth-prime/Cargo.toml b/exercises/nth-prime/Cargo.toml
index bd0526ded..fc1c776d6 100644
--- a/exercises/nth-prime/Cargo.toml
+++ b/exercises/nth-prime/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "nth_prime"
 version = "2.1.0"
 
diff --git a/exercises/nth-prime/tests/nth-prime.rs b/exercises/nth-prime/tests/nth-prime.rs
index 69c92f9da..db2af9c0b 100644
--- a/exercises/nth-prime/tests/nth-prime.rs
+++ b/exercises/nth-prime/tests/nth-prime.rs
@@ -1,4 +1,4 @@
-extern crate nth_prime as np;
+use nth_prime as np;
 
 #[test]
 fn test_first_prime() {
diff --git a/exercises/nucleotide-codons/Cargo.toml b/exercises/nucleotide-codons/Cargo.toml
index ff77d8534..1619ea0cf 100644
--- a/exercises/nucleotide-codons/Cargo.toml
+++ b/exercises/nucleotide-codons/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "nucleotide_codons"
 version = "0.1.0"
diff --git a/exercises/nucleotide-codons/tests/codons.rs b/exercises/nucleotide-codons/tests/codons.rs
index acd310f1c..2c784ce55 100644
--- a/exercises/nucleotide-codons/tests/codons.rs
+++ b/exercises/nucleotide-codons/tests/codons.rs
@@ -1,4 +1,4 @@
-extern crate nucleotide_codons as codons;
+use nucleotide_codons as codons;
 
 #[test]
 fn test_methionine() {
diff --git a/exercises/nucleotide-count/Cargo.toml b/exercises/nucleotide-count/Cargo.toml
index ae5eceadb..894c579d1 100644
--- a/exercises/nucleotide-count/Cargo.toml
+++ b/exercises/nucleotide-count/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "nucleotide-count"
 version = "1.3.0"
diff --git a/exercises/nucleotide-count/tests/nucleotide-count.rs b/exercises/nucleotide-count/tests/nucleotide-count.rs
index 403ae9c53..e910798ad 100644
--- a/exercises/nucleotide-count/tests/nucleotide-count.rs
+++ b/exercises/nucleotide-count/tests/nucleotide-count.rs
@@ -1,4 +1,4 @@
-extern crate nucleotide_count as dna;
+use nucleotide_count as dna;
 
 use std::collections::HashMap;
 
diff --git a/exercises/ocr-numbers/Cargo.toml b/exercises/ocr-numbers/Cargo.toml
index 7cc7fa0be..848a2a884 100644
--- a/exercises/ocr-numbers/Cargo.toml
+++ b/exercises/ocr-numbers/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "ocr-numbers"
 version = "0.0.0"
diff --git a/exercises/ocr-numbers/example.rs b/exercises/ocr-numbers/example.rs
index 261e9e177..98153936f 100644
--- a/exercises/ocr-numbers/example.rs
+++ b/exercises/ocr-numbers/example.rs
@@ -29,7 +29,9 @@ pub fn convert(input: &str) -> Result<String, Error> {
             let line_chars = line.chars().collect::<Vec<_>>();
 
             for (char_number, char_chunk) in line_chars.chunks(3).enumerate() {
-                let char_chars = unparsed_characters.entry(char_number).or_insert_with(Vec::new);
+                let char_chars = unparsed_characters
+                    .entry(char_number)
+                    .or_insert_with(Vec::new);
                 for c in char_chunk {
                     char_chars.push(*c);
                 }
diff --git a/exercises/ocr-numbers/tests/ocr-numbers.rs b/exercises/ocr-numbers/tests/ocr-numbers.rs
index 5e148473f..535165c39 100644
--- a/exercises/ocr-numbers/tests/ocr-numbers.rs
+++ b/exercises/ocr-numbers/tests/ocr-numbers.rs
@@ -1,4 +1,4 @@
-extern crate ocr_numbers as ocr;
+use ocr_numbers as ocr;
 
 #[test]
 #[cfg_attr(rustfmt, rustfmt_skip)]
diff --git a/exercises/paasio/Cargo.toml b/exercises/paasio/Cargo.toml
index 7f4fda53f..83a8e7309 100644
--- a/exercises/paasio/Cargo.toml
+++ b/exercises/paasio/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "paasio"
 version = "0.0.0"
diff --git a/exercises/paasio/tests/paasio.rs b/exercises/paasio/tests/paasio.rs
index 908cd9457..f9a65c925 100644
--- a/exercises/paasio/tests/paasio.rs
+++ b/exercises/paasio/tests/paasio.rs
@@ -1,4 +1,4 @@
-extern crate paasio;
+use paasio;
 
 /// test a few read scenarios
 macro_rules! test_read {
@@ -176,9 +176,7 @@ read_byte_literal(
 ));
 test_write!(#[ignore]
 write_byte_literal(
-    &[
-        2_u8, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,
-    ][..],
+    &[2_u8, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,][..],
     |d: &[u8]| d.len()
 ));
 
diff --git a/exercises/palindrome-products/Cargo.toml b/exercises/palindrome-products/Cargo.toml
index 29632100d..1d13774df 100644
--- a/exercises/palindrome-products/Cargo.toml
+++ b/exercises/palindrome-products/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "palindrome-products"
 version = "1.1.0"
 
diff --git a/exercises/palindrome-products/tests/palindrome-products.rs b/exercises/palindrome-products/tests/palindrome-products.rs
index 87975aef9..0a7cc4318 100644
--- a/exercises/palindrome-products/tests/palindrome-products.rs
+++ b/exercises/palindrome-products/tests/palindrome-products.rs
@@ -1,4 +1,3 @@
-extern crate palindrome_products;
 use palindrome_products::*;
 
 #[test]
diff --git a/exercises/pangram/Cargo.toml b/exercises/pangram/Cargo.toml
index 541dca162..a592580f1 100644
--- a/exercises/pangram/Cargo.toml
+++ b/exercises/pangram/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "pangram"
 version = "0.0.0"
diff --git a/exercises/pangram/example.rs b/exercises/pangram/example.rs
index b0fd0d433..f2870ea27 100644
--- a/exercises/pangram/example.rs
+++ b/exercises/pangram/example.rs
@@ -7,7 +7,8 @@ pub fn is_pangram(sentence: &str) -> bool {
         .chars()
         .filter(|c| c.is_alphabetic())
         .filter(|c| c.is_ascii())
-        .collect::<BTreeSet<char>>() == english_letter_set()
+        .collect::<BTreeSet<char>>()
+        == english_letter_set()
 }
 
 fn english_letter_set() -> BTreeSet<char> {
diff --git a/exercises/pangram/tests/pangram.rs b/exercises/pangram/tests/pangram.rs
index 2c3d70ac3..8db231d2e 100644
--- a/exercises/pangram/tests/pangram.rs
+++ b/exercises/pangram/tests/pangram.rs
@@ -1,5 +1,3 @@
-extern crate pangram;
-
 use pangram::*;
 
 #[test]
diff --git a/exercises/parallel-letter-frequency/Cargo.toml b/exercises/parallel-letter-frequency/Cargo.toml
index 7a2b949e0..898f4f876 100644
--- a/exercises/parallel-letter-frequency/Cargo.toml
+++ b/exercises/parallel-letter-frequency/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "parallel-letter-frequency"
 version = "0.0.0"
diff --git a/exercises/parallel-letter-frequency/tests/parallel-letter-frequency.rs b/exercises/parallel-letter-frequency/tests/parallel-letter-frequency.rs
index 7cf26fa86..51165c335 100644
--- a/exercises/parallel-letter-frequency/tests/parallel-letter-frequency.rs
+++ b/exercises/parallel-letter-frequency/tests/parallel-letter-frequency.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-extern crate parallel_letter_frequency as frequency;
+use parallel_letter_frequency as frequency;
 
 // Poem by Friedrich Schiller. The corresponding music is the European Anthem.
 const ODE_AN_DIE_FREUDE: [&'static str; 8] = [
diff --git a/exercises/pascals-triangle/Cargo.toml b/exercises/pascals-triangle/Cargo.toml
index 9c8581f05..d308b66e4 100644
--- a/exercises/pascals-triangle/Cargo.toml
+++ b/exercises/pascals-triangle/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "pascals-triangle"
 version = "1.5.0"
diff --git a/exercises/pascals-triangle/example.rs b/exercises/pascals-triangle/example.rs
index e712369fb..63f70a62d 100644
--- a/exercises/pascals-triangle/example.rs
+++ b/exercises/pascals-triangle/example.rs
@@ -4,15 +4,11 @@ pub struct PascalsTriangle {
 
 impl PascalsTriangle {
     pub fn new(row_count: u32) -> Self {
-        PascalsTriangle {
-            row_count,
-        }
+        PascalsTriangle { row_count }
     }
 
     pub fn rows(&self) -> Vec<Vec<u32>> {
-        (0..self.row_count)
-            .map(PascalsTriangle::row)
-            .collect()
+        (0..self.row_count).map(PascalsTriangle::row).collect()
     }
 
     pub fn row(number: u32) -> Vec<u32> {
diff --git a/exercises/pascals-triangle/tests/pascals-triangle.rs b/exercises/pascals-triangle/tests/pascals-triangle.rs
index d222a7056..fe2042bdc 100644
--- a/exercises/pascals-triangle/tests/pascals-triangle.rs
+++ b/exercises/pascals-triangle/tests/pascals-triangle.rs
@@ -1,5 +1,3 @@
-extern crate pascals_triangle;
-
 use pascals_triangle::*;
 
 #[test]
diff --git a/exercises/perfect-numbers/Cargo.toml b/exercises/perfect-numbers/Cargo.toml
index 988b4aa32..ac43ba13d 100644
--- a/exercises/perfect-numbers/Cargo.toml
+++ b/exercises/perfect-numbers/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "perfect_numbers"
 version = "1.1.0"
 
diff --git a/exercises/perfect-numbers/tests/perfect-numbers.rs b/exercises/perfect-numbers/tests/perfect-numbers.rs
index 25e01d3fb..a39fc52eb 100644
--- a/exercises/perfect-numbers/tests/perfect-numbers.rs
+++ b/exercises/perfect-numbers/tests/perfect-numbers.rs
@@ -1,5 +1,3 @@
-extern crate perfect_numbers;
-
 use perfect_numbers::{classify, Classification};
 
 macro_rules! tests {
diff --git a/exercises/phone-number/Cargo.toml b/exercises/phone-number/Cargo.toml
index a2c51c10a..82e5df44c 100644
--- a/exercises/phone-number/Cargo.toml
+++ b/exercises/phone-number/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "phone-number"
 version = "1.6.1"
diff --git a/exercises/phone-number/example.rs b/exercises/phone-number/example.rs
index aa9023b93..1475693f4 100644
--- a/exercises/phone-number/example.rs
+++ b/exercises/phone-number/example.rs
@@ -5,8 +5,7 @@ pub fn number(user_number: &str) -> Option<String> {
 
     if number_len < 10
         || number_len > 11
-        || (filtered_number.len() == 11
-            && filtered_number.chars().nth(0).unwrap() != '1')
+        || (filtered_number.len() == 11 && filtered_number.chars().nth(0).unwrap() != '1')
     {
         return None;
     }
diff --git a/exercises/phone-number/tests/phone-number.rs b/exercises/phone-number/tests/phone-number.rs
index 6c0fc6bdf..2bde594e2 100644
--- a/exercises/phone-number/tests/phone-number.rs
+++ b/exercises/phone-number/tests/phone-number.rs
@@ -1,4 +1,4 @@
-extern crate phone_number as phone;
+use phone_number as phone;
 
 fn process_clean_case(number: &str, expected: Option<&str>) {
     assert_eq!(phone::number(number), expected.map(|x| x.to_string()));
diff --git a/exercises/pig-latin/Cargo-example.toml b/exercises/pig-latin/Cargo-example.toml
index d10fdaca8..6452f6bea 100644
--- a/exercises/pig-latin/Cargo-example.toml
+++ b/exercises/pig-latin/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "pig-latin"
 version = "1.0.0"
 
diff --git a/exercises/pig-latin/Cargo.toml b/exercises/pig-latin/Cargo.toml
index 83e771e92..3a72f261e 100644
--- a/exercises/pig-latin/Cargo.toml
+++ b/exercises/pig-latin/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "pig-latin"
 version = "1.0.0"
 
diff --git a/exercises/pig-latin/tests/pig-latin.rs b/exercises/pig-latin/tests/pig-latin.rs
index d55dded99..6e3812744 100644
--- a/exercises/pig-latin/tests/pig-latin.rs
+++ b/exercises/pig-latin/tests/pig-latin.rs
@@ -1,4 +1,4 @@
-extern crate pig_latin as pl;
+use pig_latin as pl;
 
 #[test]
 fn test_word_beginning_with_a() {
diff --git a/exercises/poker/Cargo-example.toml b/exercises/poker/Cargo-example.toml
index f1c6c9f3f..57657757c 100644
--- a/exercises/poker/Cargo-example.toml
+++ b/exercises/poker/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "poker"
 version = "1.0.0"
 
diff --git a/exercises/poker/Cargo.toml b/exercises/poker/Cargo.toml
index 6e15b459c..647413b5d 100644
--- a/exercises/poker/Cargo.toml
+++ b/exercises/poker/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "poker"
 version = "1.1.0"
 
diff --git a/exercises/poker/example.rs b/exercises/poker/example.rs
index 002914274..33a649b81 100644
--- a/exercises/poker/example.rs
+++ b/exercises/poker/example.rs
@@ -12,12 +12,10 @@ use counter::Counter;
 /// Note the type signature: this function should return _the same_ reference to
 /// the winning hand(s) as were passed in, not reconstructed strings which happen to be equal.
 pub fn winning_hands<'a>(hands: &[&'a str]) -> Option<Vec<&'a str>> {
-    let mut hands = try_opt!(
-        hands
-            .iter()
-            .map(|source| Hand::try_from(source))
-            .collect::<Option<Vec<Hand>>>()
-    );
+    let mut hands = try_opt!(hands
+        .iter()
+        .map(|source| Hand::try_from(source))
+        .collect::<Option<Vec<Hand>>>());
     hands.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Less));
     hands.last().map(|last| {
         hands
@@ -39,7 +37,7 @@ enum Suit {
 
 impl Suit {
     fn try_from(source: &str) -> Option<Suit> {
-        use Suit::*;
+        use crate::Suit::*;
         match source {
             "S" => Some(Spades),
             "C" => Some(Clubs),
@@ -52,7 +50,7 @@ impl Suit {
 
 impl fmt::Display for Suit {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use Suit::*;
+        use crate::Suit::*;
         write!(
             f,
             "{}",
@@ -77,7 +75,7 @@ enum Rank {
 
 impl Rank {
     fn try_from(source: &str) -> Option<Rank> {
-        use Rank::*;
+        use crate::Rank::*;
         match source {
             "A" => Some(Ace),
             "K" => Some(King),
@@ -97,7 +95,7 @@ impl Rank {
     }
 
     fn value(&self) -> usize {
-        use Rank::*;
+        use crate::Rank::*;
         match *self {
             Ace => 14,
             King => 13,
@@ -110,7 +108,7 @@ impl Rank {
 
 impl fmt::Display for Rank {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use Rank::*;
+        use crate::Rank::*;
         let num_str; // early declaration to placate NLL of Number case
         write!(
             f,
@@ -181,7 +179,8 @@ impl PokerHand {
     fn is_ace_low_straight(cards: &[Card]) -> bool {
         // special case: ace-low straight
         // still depends on the sorted precondition
-        cards[0].rank.value() == 2 && cards[4].rank == Rank::Ace
+        cards[0].rank.value() == 2
+            && cards[4].rank == Rank::Ace
             && cards
                 .windows(2)
                 .take(3) // (0, 1), (1, 2), (2, 3) --> skips 4, ace
@@ -195,7 +194,8 @@ impl PokerHand {
             let is_flush = suit_counter
                 .most_common()
                 .map(|(_suit, count)| count)
-                .next() == Some(5);
+                .next()
+                == Some(5);
             // Note that `is_straight` depends on a precondition: it only works
             // if the input `cards` are sorted by rank value ascending.
             let is_straight = cards
@@ -250,12 +250,10 @@ struct Hand<'a> {
 
 impl<'a> Hand<'a> {
     fn try_from(source: &'a str) -> Option<Hand> {
-        let mut cards = try_opt!(
-            source
-                .split_whitespace()
-                .map(|s| Card::try_from(s))
-                .collect::<Option<Vec<Card>>>()
-        );
+        let mut cards = try_opt!(source
+            .split_whitespace()
+            .map(|s| Card::try_from(s))
+            .collect::<Option<Vec<Card>>>());
         cards.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Less));
         if cards.len() == 5 {
             Some(Hand {
@@ -325,7 +323,7 @@ impl<'a> fmt::Display for Hand<'a> {
 impl<'a> PartialOrd for Hand<'a> {
     fn partial_cmp(&self, other: &Hand) -> Option<Ordering> {
         Some(self.hand_type.cmp(&other.hand_type).then_with(|| {
-            use PokerHand::*;
+            use crate::PokerHand::*;
             match self.hand_type {
                 HighCard => self.cmp_high_card(other, 4),
                 OnePair => self.cmp_cascade_by_freq(other),
diff --git a/exercises/poker/tests/poker.rs b/exercises/poker/tests/poker.rs
index 9f575de2d..b3d7b8ca4 100644
--- a/exercises/poker/tests/poker.rs
+++ b/exercises/poker/tests/poker.rs
@@ -1,4 +1,3 @@
-extern crate poker;
 use poker::winning_hands;
 use std::collections::HashSet;
 
diff --git a/exercises/prime-factors/Cargo.toml b/exercises/prime-factors/Cargo.toml
index 441b7fd6a..70727e601 100644
--- a/exercises/prime-factors/Cargo.toml
+++ b/exercises/prime-factors/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "prime_factors"
 version = "1.1.0"
 
diff --git a/exercises/prime-factors/tests/prime-factors.rs b/exercises/prime-factors/tests/prime-factors.rs
index e5953cc55..aee6cdaaa 100644
--- a/exercises/prime-factors/tests/prime-factors.rs
+++ b/exercises/prime-factors/tests/prime-factors.rs
@@ -1,5 +1,3 @@
-extern crate prime_factors;
-
 use prime_factors::factors;
 
 #[test]
diff --git a/exercises/protein-translation/Cargo.toml b/exercises/protein-translation/Cargo.toml
index c29ceeff6..12bb32a92 100644
--- a/exercises/protein-translation/Cargo.toml
+++ b/exercises/protein-translation/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "protein-translation"
 version = "0.1.0"
diff --git a/exercises/protein-translation/tests/proteins.rs b/exercises/protein-translation/tests/proteins.rs
index 0f0665633..494aba130 100644
--- a/exercises/protein-translation/tests/proteins.rs
+++ b/exercises/protein-translation/tests/proteins.rs
@@ -1,4 +1,4 @@
-extern crate protein_translation as proteins;
+use protein_translation as proteins;
 
 #[test]
 fn test_methionine() {
diff --git a/exercises/proverb/Cargo.toml b/exercises/proverb/Cargo.toml
index 5cd818522..4e09ea104 100644
--- a/exercises/proverb/Cargo.toml
+++ b/exercises/proverb/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "proverb"
 version = "1.1.0"
 
diff --git a/exercises/proverb/tests/proverb.rs b/exercises/proverb/tests/proverb.rs
index f69782508..fbf8e8cea 100644
--- a/exercises/proverb/tests/proverb.rs
+++ b/exercises/proverb/tests/proverb.rs
@@ -1,5 +1,3 @@
-extern crate proverb;
-
 use proverb::build_proverb;
 
 #[test]
@@ -8,7 +6,8 @@ fn test_two_pieces() {
     let expected = vec![
         "For want of a nail the shoe was lost.",
         "And all for the want of a nail.",
-    ].join("\n");
+    ]
+    .join("\n");
     assert_eq!(build_proverb(&input), expected);
 }
 
@@ -21,7 +20,8 @@ fn test_three_pieces() {
         "For want of a nail the shoe was lost.",
         "For want of a shoe the horse was lost.",
         "And all for the want of a nail.",
-    ].join("\n");
+    ]
+    .join("\n");
     assert_eq!(build_proverb(&input), expected);
 }
 
@@ -55,7 +55,8 @@ fn test_full() {
         "For want of a message the battle was lost.",
         "For want of a battle the kingdom was lost.",
         "And all for the want of a nail.",
-    ].join("\n");
+    ]
+    .join("\n");
     assert_eq!(build_proverb(&input), expected);
 }
 
@@ -68,6 +69,7 @@ fn test_three_pieces_modernized() {
         "For want of a gun the soldier was lost.",
         "For want of a soldier the battle was lost.",
         "And all for the want of a pin.",
-    ].join("\n");
+    ]
+    .join("\n");
     assert_eq!(build_proverb(&input), expected);
 }
diff --git a/exercises/pythagorean-triplet/Cargo.toml b/exercises/pythagorean-triplet/Cargo.toml
index 1aec82db6..b0d9ae8fa 100644
--- a/exercises/pythagorean-triplet/Cargo.toml
+++ b/exercises/pythagorean-triplet/Cargo.toml
@@ -1,5 +1,6 @@
 [dependencies]
 
 [package]
+edition = "2018"
 name = "pythagorean_triplet"
 version = "1.0.0"
diff --git a/exercises/pythagorean-triplet/tests/pythagorean-triplet.rs b/exercises/pythagorean-triplet/tests/pythagorean-triplet.rs
index 3198ca26c..9dfb38d5f 100644
--- a/exercises/pythagorean-triplet/tests/pythagorean-triplet.rs
+++ b/exercises/pythagorean-triplet/tests/pythagorean-triplet.rs
@@ -1,5 +1,3 @@
-extern crate pythagorean_triplet;
-
 use pythagorean_triplet::find;
 use std::{collections::HashSet, iter::FromIterator};
 
diff --git a/exercises/queen-attack/Cargo.toml b/exercises/queen-attack/Cargo.toml
index 5103ef806..ffb4cd888 100644
--- a/exercises/queen-attack/Cargo.toml
+++ b/exercises/queen-attack/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "queen-attack"
 version = "2.2.0"
diff --git a/exercises/queen-attack/example.rs b/exercises/queen-attack/example.rs
index dea80dbec..76808ae09 100644
--- a/exercises/queen-attack/example.rs
+++ b/exercises/queen-attack/example.rs
@@ -34,10 +34,7 @@ pub struct ChessPosition {
 
 impl ChessPosition {
     pub fn new(rank: i8, file: i8) -> Option<Self> {
-        let position = ChessPosition {
-            rank,
-            file,
-        };
+        let position = ChessPosition { rank, file };
 
         if position.is_valid() {
             Some(position)
diff --git a/exercises/queen-attack/tests/queen-attack.rs b/exercises/queen-attack/tests/queen-attack.rs
index 5b6caff6e..6b0eaeada 100644
--- a/exercises/queen-attack/tests/queen-attack.rs
+++ b/exercises/queen-attack/tests/queen-attack.rs
@@ -1,5 +1,3 @@
-extern crate queen_attack;
-
 use queen_attack::*;
 
 #[test]
diff --git a/exercises/rail-fence-cipher/Cargo.toml b/exercises/rail-fence-cipher/Cargo.toml
index ff5617793..f6b8092c2 100644
--- a/exercises/rail-fence-cipher/Cargo.toml
+++ b/exercises/rail-fence-cipher/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "rail_fence_cipher"
 version = "1.1.0"
diff --git a/exercises/rail-fence-cipher/tests/rail-fence-cipher.rs b/exercises/rail-fence-cipher/tests/rail-fence-cipher.rs
index c07f8c395..3170cb117 100644
--- a/exercises/rail-fence-cipher/tests/rail-fence-cipher.rs
+++ b/exercises/rail-fence-cipher/tests/rail-fence-cipher.rs
@@ -8,7 +8,6 @@
 //! The tests do not expect any normalization or cleaning.
 //! That trade is tested in enough other exercises.
 
-extern crate rail_fence_cipher;
 use rail_fence_cipher::*;
 
 /// Process a single test case for the property `encode`
diff --git a/exercises/raindrops/Cargo.toml b/exercises/raindrops/Cargo.toml
index 34a693845..f37aa78c8 100644
--- a/exercises/raindrops/Cargo.toml
+++ b/exercises/raindrops/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "raindrops"
 version = "1.1.0"
diff --git a/exercises/raindrops/tests/raindrops.rs b/exercises/raindrops/tests/raindrops.rs
index 6e03780fa..22b69391b 100644
--- a/exercises/raindrops/tests/raindrops.rs
+++ b/exercises/raindrops/tests/raindrops.rs
@@ -1,4 +1,4 @@
-extern crate raindrops;
+use raindrops;
 
 #[test]
 fn test_1() {
diff --git a/exercises/react/Cargo.toml b/exercises/react/Cargo.toml
index 1c2ac5a2f..d957c6cc4 100644
--- a/exercises/react/Cargo.toml
+++ b/exercises/react/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "react"
 version = "2.0.0"
diff --git a/exercises/react/example.rs b/exercises/react/example.rs
index 21c4043c0..d75fb3e92 100644
--- a/exercises/react/example.rs
+++ b/exercises/react/example.rs
@@ -99,12 +99,16 @@ impl<'a, T: Copy + PartialEq> Reactor<'a, T> {
         // so that we don't perform an incorrect partial write.
         for &dep in dependencies {
             match dep {
-                CellID::Input(InputCellID(id)) => if id >= self.inputs.len() {
-                    return Err(dep);
-                },
-                CellID::Compute(ComputeCellID(id)) => if id >= self.computes.len() {
-                    return Err(dep);
-                },
+                CellID::Input(InputCellID(id)) => {
+                    if id >= self.inputs.len() {
+                        return Err(dep);
+                    }
+                }
+                CellID::Compute(ComputeCellID(id)) => {
+                    if id >= self.computes.len() {
+                        return Err(dep);
+                    }
+                }
             }
         }
         let new_id = ComputeCellID(self.computes.len());
diff --git a/exercises/react/tests/react.rs b/exercises/react/tests/react.rs
index 65f71c914..cd26a361e 100644
--- a/exercises/react/tests/react.rs
+++ b/exercises/react/tests/react.rs
@@ -1,5 +1,3 @@
-extern crate react;
-
 use react::*;
 
 #[test]
@@ -172,11 +170,9 @@ fn compute_cells_fire_callbacks() {
     let output = reactor
         .create_compute(&[CellID::Input(input)], |v| v[0] + 1)
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb.callback_called(v))
+        .is_some());
     assert!(reactor.set_value(input, 3));
     cb.expect_to_have_been_called_with(4);
 }
@@ -207,11 +203,9 @@ fn callbacks_only_fire_on_change() {
             |v| if v[0] < 3 { 111 } else { 222 },
         )
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb.callback_called(v))
+        .is_some());
 
     assert!(reactor.set_value(input, 2));
     cb.expect_not_to_have_been_called();
@@ -228,11 +222,9 @@ fn callbacks_can_be_called_multiple_times() {
     let output = reactor
         .create_compute(&[CellID::Input(input)], |v| v[0] + 1)
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb.callback_called(v))
+        .is_some());
 
     assert!(reactor.set_value(input, 2));
     cb.expect_to_have_been_called_with(3);
@@ -253,16 +245,12 @@ fn callbacks_can_be_called_from_multiple_cells() {
     let minus_one = reactor
         .create_compute(&[CellID::Input(input)], |v| v[0] - 1)
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(plus_one, |v| cb1.callback_called(v))
-            .is_some()
-    );
-    assert!(
-        reactor
-            .add_callback(minus_one, |v| cb2.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(plus_one, |v| cb1.callback_called(v))
+        .is_some());
+    assert!(reactor
+        .add_callback(minus_one, |v| cb2.callback_called(v))
+        .is_some());
 
     assert!(reactor.set_value(input, 10));
     cb1.expect_to_have_been_called_with(11);
@@ -285,22 +273,18 @@ fn callbacks_can_be_added_and_removed() {
     let callback = reactor
         .add_callback(output, |v| cb1.callback_called(v))
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb2.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb2.callback_called(v))
+        .is_some());
 
     assert!(reactor.set_value(input, 31));
     cb1.expect_to_have_been_called_with(32);
     cb2.expect_to_have_been_called_with(32);
 
     assert!(reactor.remove_callback(output, callback).is_ok());
-    assert!(
-        reactor
-            .add_callback(output, |v| cb3.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb3.callback_called(v))
+        .is_some());
 
     assert!(reactor.set_value(input, 41));
     cb1.expect_not_to_have_been_called();
@@ -322,11 +306,9 @@ fn removing_a_callback_multiple_times_doesnt_interfere_with_other_callbacks() {
     let callback = reactor
         .add_callback(output, |v| cb1.callback_called(v))
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb2.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb2.callback_called(v))
+        .is_some());
     // We want the first remove to be Ok, but the others should be errors.
     assert!(reactor.remove_callback(output, callback).is_ok());
     for _ in 1..5 {
@@ -362,11 +344,9 @@ fn callbacks_should_only_be_called_once_even_if_multiple_dependencies_change() {
             |v| v[0] * v[1],
         )
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(output, |v| cb.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(output, |v| cb.callback_called(v))
+        .is_some());
     assert!(reactor.set_value(input, 4));
     cb.expect_to_have_been_called_with(10);
 }
@@ -389,11 +369,9 @@ fn callbacks_should_not_be_called_if_dependencies_change_but_output_value_doesnt
             |v| v[0] - v[1],
         )
         .unwrap();
-    assert!(
-        reactor
-            .add_callback(always_two, |v| cb.callback_called(v))
-            .is_some()
-    );
+    assert!(reactor
+        .add_callback(always_two, |v| cb.callback_called(v))
+        .is_some());
     for i in 2..5 {
         assert!(reactor.set_value(input, i));
         cb.expect_not_to_have_been_called();
diff --git a/exercises/rectangles/Cargo.toml b/exercises/rectangles/Cargo.toml
index 3fa7ec041..d692cc168 100644
--- a/exercises/rectangles/Cargo.toml
+++ b/exercises/rectangles/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "rectangles"
 version = "1.1.0"
diff --git a/exercises/rectangles/tests/rectangles.rs b/exercises/rectangles/tests/rectangles.rs
index b61dc4a95..e079f0599 100644
--- a/exercises/rectangles/tests/rectangles.rs
+++ b/exercises/rectangles/tests/rectangles.rs
@@ -1,4 +1,4 @@
-extern crate rectangles;
+
 
 use rectangles::count;
 
diff --git a/exercises/reverse-string/Cargo.toml b/exercises/reverse-string/Cargo.toml
index 034018e3e..ad556d3af 100644
--- a/exercises/reverse-string/Cargo.toml
+++ b/exercises/reverse-string/Cargo.toml
@@ -4,5 +4,6 @@
 grapheme = []
 
 [package]
+edition = "2018"
 name = "reverse_string"
 version = "1.1.0"
diff --git a/exercises/reverse-string/tests/reverse-string.rs b/exercises/reverse-string/tests/reverse-string.rs
index d6de3bc01..5b1145223 100644
--- a/exercises/reverse-string/tests/reverse-string.rs
+++ b/exercises/reverse-string/tests/reverse-string.rs
@@ -5,7 +5,6 @@
 //! [script]: https://github.com/exercism/rust/blob/b829ce2/bin/init_exercise.py
 //! [canonical-data]: https://raw.githubusercontent.com/exercism/problem-specifications/master/exercises/reverse-string/canonical_data.json
 
-extern crate reverse_string;
 use reverse_string::*;
 
 /// Process a single test case for the property `reverse`
diff --git a/exercises/rna-transcription/Cargo.toml b/exercises/rna-transcription/Cargo.toml
index 1b205b181..00b55408e 100644
--- a/exercises/rna-transcription/Cargo.toml
+++ b/exercises/rna-transcription/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "rna-transcription"
 version = "1.0.0"
diff --git a/exercises/rna-transcription/tests/rna-transcription.rs b/exercises/rna-transcription/tests/rna-transcription.rs
index 76138a94c..feed29b34 100644
--- a/exercises/rna-transcription/tests/rna-transcription.rs
+++ b/exercises/rna-transcription/tests/rna-transcription.rs
@@ -1,4 +1,4 @@
-extern crate rna_transcription as dna;
+use rna_transcription as dna;
 
 #[test]
 fn test_valid_dna_input() {
diff --git a/exercises/robot-name/Cargo-example.toml b/exercises/robot-name/Cargo-example.toml
index 0a96b50b8..947865342 100644
--- a/exercises/robot-name/Cargo-example.toml
+++ b/exercises/robot-name/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "robot-name"
 version = "0.0.0"
 
diff --git a/exercises/robot-name/Cargo.toml b/exercises/robot-name/Cargo.toml
index 789f265e7..897aa15bb 100644
--- a/exercises/robot-name/Cargo.toml
+++ b/exercises/robot-name/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "robot-name"
 version = "0.0.0"
 
diff --git a/exercises/robot-name/tests/robot-name.rs b/exercises/robot-name/tests/robot-name.rs
index 27236fa75..bfe0269ac 100644
--- a/exercises/robot-name/tests/robot-name.rs
+++ b/exercises/robot-name/tests/robot-name.rs
@@ -1,4 +1,4 @@
-extern crate robot_name as robot;
+use robot_name as robot;
 
 fn assert_name_matches_pattern(n: &str) {
     assert!(n.len() == 5, "name is exactly 5 characters long");
diff --git a/exercises/robot-simulator/Cargo.toml b/exercises/robot-simulator/Cargo.toml
index dd962d6c5..7d5b75fca 100644
--- a/exercises/robot-simulator/Cargo.toml
+++ b/exercises/robot-simulator/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "robot-simulator"
 version = "2.2.0"
diff --git a/exercises/robot-simulator/tests/robot-simulator.rs b/exercises/robot-simulator/tests/robot-simulator.rs
index 81528ba76..1c33c2f18 100644
--- a/exercises/robot-simulator/tests/robot-simulator.rs
+++ b/exercises/robot-simulator/tests/robot-simulator.rs
@@ -1,5 +1,3 @@
-extern crate robot_simulator;
-
 use robot_simulator::*;
 
 #[test]
diff --git a/exercises/roman-numerals/Cargo.toml b/exercises/roman-numerals/Cargo.toml
index 6ae5e099d..8f7918cac 100644
--- a/exercises/roman-numerals/Cargo.toml
+++ b/exercises/roman-numerals/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "roman-numerals"
 version = "1.0.0"
diff --git a/exercises/roman-numerals/src/lib.rs b/exercises/roman-numerals/src/lib.rs
index 21d8072c8..96ed9acef 100644
--- a/exercises/roman-numerals/src/lib.rs
+++ b/exercises/roman-numerals/src/lib.rs
@@ -3,7 +3,7 @@ use std::fmt::{Display, Formatter, Result};
 pub struct Roman;
 
 impl Display for Roman {
-    fn fmt(&self, _f: &mut Formatter) -> Result {
+    fn fmt(&self, _f: &mut Formatter<'_>) -> Result {
         unimplemented!("Return a roman-numeral string representation of the Roman object");
     }
 }
diff --git a/exercises/roman-numerals/tests/roman-numerals.rs b/exercises/roman-numerals/tests/roman-numerals.rs
index c4e302a86..cb175fec2 100644
--- a/exercises/roman-numerals/tests/roman-numerals.rs
+++ b/exercises/roman-numerals/tests/roman-numerals.rs
@@ -1,5 +1,3 @@
-extern crate roman_numerals;
-
 use roman_numerals::*;
 
 #[test]
diff --git a/exercises/rotational-cipher/Cargo.toml b/exercises/rotational-cipher/Cargo.toml
index aabf2b132..19647c6de 100644
--- a/exercises/rotational-cipher/Cargo.toml
+++ b/exercises/rotational-cipher/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "rotational-cipher"
 version = "1.0.0"
diff --git a/exercises/rotational-cipher/tests/rotational-cipher.rs b/exercises/rotational-cipher/tests/rotational-cipher.rs
index 7405062ad..64f0d66c4 100644
--- a/exercises/rotational-cipher/tests/rotational-cipher.rs
+++ b/exercises/rotational-cipher/tests/rotational-cipher.rs
@@ -1,4 +1,4 @@
-extern crate rotational_cipher as cipher;
+use rotational_cipher as cipher;
 
 #[test]
 fn rotate_a_1() {
diff --git a/exercises/run-length-encoding/Cargo.toml b/exercises/run-length-encoding/Cargo.toml
index a6866b5d1..f805b78c8 100644
--- a/exercises/run-length-encoding/Cargo.toml
+++ b/exercises/run-length-encoding/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "run-length-encoding"
 version = "1.1.0"
 
diff --git a/exercises/run-length-encoding/tests/run-length-encoding.rs b/exercises/run-length-encoding/tests/run-length-encoding.rs
index 70359920c..bcb208e36 100644
--- a/exercises/run-length-encoding/tests/run-length-encoding.rs
+++ b/exercises/run-length-encoding/tests/run-length-encoding.rs
@@ -1,4 +1,4 @@
-extern crate run_length_encoding as rle;
+use run_length_encoding as rle;
 
 // encoding tests
 
diff --git a/exercises/saddle-points/Cargo.toml b/exercises/saddle-points/Cargo.toml
index fc43d00f7..5f262e2dc 100644
--- a/exercises/saddle-points/Cargo.toml
+++ b/exercises/saddle-points/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "saddle-points"
 version = "1.3.0"
 
diff --git a/exercises/saddle-points/tests/saddle-points.rs b/exercises/saddle-points/tests/saddle-points.rs
index 8fd853e13..287c3dad7 100644
--- a/exercises/saddle-points/tests/saddle-points.rs
+++ b/exercises/saddle-points/tests/saddle-points.rs
@@ -1,4 +1,4 @@
-extern crate saddle_points;
+use saddle_points;
 
 use saddle_points::find_saddle_points;
 
@@ -11,11 +11,7 @@ fn find_sorted_saddle_points(input: &[Vec<u64>]) -> Vec<(usize, usize)> {
 
 #[test]
 fn identify_single_saddle_point() {
-    let input = vec![
-        vec![9, 8, 7],
-        vec![5, 3, 2],
-        vec![6, 6, 7],
-    ];
+    let input = vec![vec![9, 8, 7], vec![5, 3, 2], vec![6, 6, 7]];
     assert_eq!(vec![(1, 0)], find_saddle_points(&input));
 }
 
@@ -30,11 +26,7 @@ fn identify_empty_matrix() {
 #[test]
 #[ignore]
 fn identify_lack_of_saddle_point() {
-    let input = vec![
-        vec![1, 2, 3],
-        vec![3, 1, 2],
-        vec![2, 3, 1],
-    ];
+    let input = vec![vec![1, 2, 3], vec![3, 1, 2], vec![2, 3, 1]];
     let expected: Vec<(usize, usize)> = Vec::new();
     assert_eq!(expected, find_saddle_points(&input));
 }
@@ -42,11 +34,7 @@ fn identify_lack_of_saddle_point() {
 #[test]
 #[ignore]
 fn multiple_saddle_points_in_col() {
-    let input = vec![
-        vec![4, 5, 4],
-        vec![3, 5, 5],
-        vec![1, 5, 4],
-    ];
+    let input = vec![vec![4, 5, 4], vec![3, 5, 5], vec![1, 5, 4]];
     assert_eq!(
         vec![(0, 1), (1, 1), (2, 1)],
         find_sorted_saddle_points(&input)
@@ -56,11 +44,7 @@ fn multiple_saddle_points_in_col() {
 #[test]
 #[ignore]
 fn multiple_saddle_points_in_row() {
-    let input = vec![
-        vec![6, 7, 8],
-        vec![5, 5, 5],
-        vec![7, 5, 6],
-    ];
+    let input = vec![vec![6, 7, 8], vec![5, 5, 5], vec![7, 5, 6]];
     assert_eq!(
         vec![(1, 0), (1, 1), (1, 2)],
         find_sorted_saddle_points(&input)
@@ -70,11 +54,7 @@ fn multiple_saddle_points_in_row() {
 #[test]
 #[ignore]
 fn identify_bottom_right_saddle_point() {
-    let input = vec![
-        vec![8, 7, 9],
-        vec![6, 7, 6],
-        vec![3, 2, 5],
-    ];
+    let input = vec![vec![8, 7, 9], vec![6, 7, 6], vec![3, 2, 5]];
     assert_eq!(vec![(2, 2)], find_saddle_points(&input));
 }
 
@@ -82,54 +62,47 @@ fn identify_bottom_right_saddle_point() {
 #[test]
 #[ignore]
 fn non_square_matrix_high() {
-    let input = vec![
-        vec![1, 5],
-        vec![3, 6],
-        vec![2, 7],
-        vec![3, 8],
-    ];
+    let input = vec![vec![1, 5], vec![3, 6], vec![2, 7], vec![3, 8]];
     assert_eq!(vec![(0, 1)], find_saddle_points(&input));
 }
 
 #[test]
 #[ignore]
 fn non_square_matrix_wide() {
-    let input = vec![
-        vec![3, 1, 3],
-        vec![3, 2, 4]
-    ];
+    let input = vec![vec![3, 1, 3], vec![3, 2, 4]];
     assert_eq!(vec![(0, 0), (0, 2)], find_sorted_saddle_points(&input));
 }
 
 #[test]
 #[ignore]
 fn single_column_matrix() {
-    let input = vec![
-        vec![2],
-        vec![1],
-        vec![4],
-        vec![1],
-    ];
+    let input = vec![vec![2], vec![1], vec![4], vec![1]];
     assert_eq!(vec![(1, 0), (3, 0)], find_sorted_saddle_points(&input));
 }
 
 #[test]
 #[ignore]
 fn single_row_matrix() {
-    let input = vec![
-        vec![2, 5, 3, 5],
-    ];
+    let input = vec![vec![2, 5, 3, 5]];
     assert_eq!(vec![(0, 1), (0, 3)], find_sorted_saddle_points(&input));
 }
 
 #[test]
 #[ignore]
 fn identify_all_saddle_points() {
-    let input = vec![
-        vec![5, 5, 5],
-        vec![5, 5, 5],
-        vec![5, 5, 5],
-    ];
-    assert_eq!(vec![(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)], find_saddle_points(&input));
+    let input = vec![vec![5, 5, 5], vec![5, 5, 5], vec![5, 5, 5]];
+    assert_eq!(
+        vec![
+            (0, 0),
+            (0, 1),
+            (0, 2),
+            (1, 0),
+            (1, 1),
+            (1, 2),
+            (2, 0),
+            (2, 1),
+            (2, 2)
+        ],
+        find_saddle_points(&input)
+    );
 }
-
diff --git a/exercises/say/Cargo.toml b/exercises/say/Cargo.toml
index 852b991d1..48983e26b 100644
--- a/exercises/say/Cargo.toml
+++ b/exercises/say/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "say"
 version = "1.2.0"
diff --git a/exercises/say/tests/say.rs b/exercises/say/tests/say.rs
index ea22c50e6..92a682ba5 100644
--- a/exercises/say/tests/say.rs
+++ b/exercises/say/tests/say.rs
@@ -1,4 +1,4 @@
-extern crate say;
+use say;
 
 // Note: No tests created using 'and' with numbers.
 // Apparently Most American English does not use the 'and' with numbers,
diff --git a/exercises/scale-generator/Cargo-example.toml b/exercises/scale-generator/Cargo-example.toml
index a67d9247c..e029a22af 100644
--- a/exercises/scale-generator/Cargo-example.toml
+++ b/exercises/scale-generator/Cargo-example.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "scale_generator"
 version = "1.0.0"
 
diff --git a/exercises/scale-generator/Cargo.toml b/exercises/scale-generator/Cargo.toml
index f07d90d27..f59bf1622 100644
--- a/exercises/scale-generator/Cargo.toml
+++ b/exercises/scale-generator/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "scale_generator"
 version = "2.0.0"
 
diff --git a/exercises/scale-generator/example.rs b/exercises/scale-generator/example.rs
index 0aa2be63e..5f1dc5d7b 100644
--- a/exercises/scale-generator/example.rs
+++ b/exercises/scale-generator/example.rs
@@ -119,7 +119,7 @@ pub mod interval {
 }
 
 pub mod note {
-    use interval::Interval;
+    use crate::Interval;
     use num_traits::{FromPrimitive, ToPrimitive};
     use std::fmt;
     use std::ops::AddAssign;
@@ -305,7 +305,8 @@ pub mod note {
             Semitone::from_i8(
                 (SEMITONES + n.tonic.to_i8().unwrap() + n.accidental.map_or(0, |a| a.to_i8()))
                     % SEMITONES,
-            ).expect("must have valid semitone")
+            )
+            .expect("must have valid semitone")
         }
     }
 
@@ -314,8 +315,9 @@ pub mod note {
             *self = Semitone::from_i8(
                 (SEMITONES + Semitone::from(*self).to_i8().unwrap() + rhs.to_i8().unwrap())
                     % SEMITONES,
-            ).unwrap()
-                .into();
+            )
+            .unwrap()
+            .into();
         }
     }
 
diff --git a/exercises/scale-generator/tests/scale-generator.rs b/exercises/scale-generator/tests/scale-generator.rs
index 55970ed5b..9f8c3c930 100644
--- a/exercises/scale-generator/tests/scale-generator.rs
+++ b/exercises/scale-generator/tests/scale-generator.rs
@@ -5,7 +5,6 @@
 //! [script]: https://github.com/exercism/rust/blob/master/bin/init_exercise.py
 //! [canonical-data]: https://raw.githubusercontent.com/exercism/problem-specifications/master/exercises/scale-generator/canonical_data.json
 
-extern crate scale_generator;
 use scale_generator::*;
 
 /// Process a single test case for the property `chromatic`
@@ -36,7 +35,7 @@ fn test_chromatic_scale_with_sharps() {
     process_chromatic_case(
         "C",
         &[
-            "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"
+            "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B",
         ],
     );
 }
@@ -48,7 +47,7 @@ fn test_chromatic_scale_with_flats() {
     process_chromatic_case(
         "F",
         &[
-            "F", "Gb", "G", "Ab", "A", "Bb", "B", "C", "Db", "D", "Eb", "E"
+            "F", "Gb", "G", "Ab", "A", "Bb", "B", "C", "Db", "D", "Eb", "E",
         ],
     );
 }
diff --git a/exercises/scrabble-score/Cargo.toml b/exercises/scrabble-score/Cargo.toml
index 70bb582f7..e25de5d5b 100644
--- a/exercises/scrabble-score/Cargo.toml
+++ b/exercises/scrabble-score/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "scrabble-score"
 version = "1.1.0"
diff --git a/exercises/scrabble-score/tests/scrabble-score.rs b/exercises/scrabble-score/tests/scrabble-score.rs
index 03585a03f..ab7439a92 100644
--- a/exercises/scrabble-score/tests/scrabble-score.rs
+++ b/exercises/scrabble-score/tests/scrabble-score.rs
@@ -1,5 +1,3 @@
-extern crate scrabble_score;
-
 use scrabble_score::*;
 
 #[test]
diff --git a/exercises/series/Cargo.toml b/exercises/series/Cargo.toml
index f8da3cd2d..523a7795f 100644
--- a/exercises/series/Cargo.toml
+++ b/exercises/series/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "series"
 version = "0.1.0"
 
diff --git a/exercises/series/tests/series.rs b/exercises/series/tests/series.rs
index ce53c3666..bbaf8a7c5 100644
--- a/exercises/series/tests/series.rs
+++ b/exercises/series/tests/series.rs
@@ -1,4 +1,3 @@
-extern crate series;
 use series::*;
 
 #[test]
diff --git a/exercises/sieve/Cargo.toml b/exercises/sieve/Cargo.toml
index 1389a4a13..3af912356 100644
--- a/exercises/sieve/Cargo.toml
+++ b/exercises/sieve/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "sieve"
 version = "1.1.0"
diff --git a/exercises/sieve/tests/sieve.rs b/exercises/sieve/tests/sieve.rs
index cafff543d..9b94538c8 100644
--- a/exercises/sieve/tests/sieve.rs
+++ b/exercises/sieve/tests/sieve.rs
@@ -1,4 +1,4 @@
-extern crate sieve;
+use sieve;
 
 #[test]
 fn limit_lower_than_the_first_prime() {
diff --git a/exercises/simple-cipher/Cargo.toml b/exercises/simple-cipher/Cargo.toml
index 504454426..fdc32dfdb 100644
--- a/exercises/simple-cipher/Cargo.toml
+++ b/exercises/simple-cipher/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "simple-cipher"
 version = "0.0.0"
 
diff --git a/exercises/simple-cipher/tests/simple-cipher.rs b/exercises/simple-cipher/tests/simple-cipher.rs
index 463a506e9..7ebb2be1b 100644
--- a/exercises/simple-cipher/tests/simple-cipher.rs
+++ b/exercises/simple-cipher/tests/simple-cipher.rs
@@ -1,4 +1,3 @@
-extern crate simple_cipher;
 use simple_cipher::*;
 use std::collections::HashSet;
 
diff --git a/exercises/simple-linked-list/Cargo.toml b/exercises/simple-linked-list/Cargo.toml
index a1c07edcc..25a62e7bf 100644
--- a/exercises/simple-linked-list/Cargo.toml
+++ b/exercises/simple-linked-list/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "simple_linked_list"
 version = "0.1.0"
 
diff --git a/exercises/simple-linked-list/tests/simple-linked-list.rs b/exercises/simple-linked-list/tests/simple-linked-list.rs
index 84ddd5a1c..3bb926c65 100644
--- a/exercises/simple-linked-list/tests/simple-linked-list.rs
+++ b/exercises/simple-linked-list/tests/simple-linked-list.rs
@@ -1,5 +1,3 @@
-extern crate simple_linked_list;
-
 use simple_linked_list::SimpleLinkedList;
 
 #[test]
diff --git a/exercises/space-age/Cargo.toml b/exercises/space-age/Cargo.toml
index 2dde0e801..6f68722fb 100644
--- a/exercises/space-age/Cargo.toml
+++ b/exercises/space-age/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "space-age"
 version = "1.1.0"
diff --git a/exercises/space-age/tests/space-age.rs b/exercises/space-age/tests/space-age.rs
index 29c660299..8e5400ae6 100644
--- a/exercises/space-age/tests/space-age.rs
+++ b/exercises/space-age/tests/space-age.rs
@@ -1,5 +1,3 @@
-extern crate space_age;
-
 use space_age::*;
 
 fn assert_in_delta(expected: f64, actual: f64) {
diff --git a/exercises/spiral-matrix/Cargo.toml b/exercises/spiral-matrix/Cargo.toml
index a12046f0b..a4e254de5 100644
--- a/exercises/spiral-matrix/Cargo.toml
+++ b/exercises/spiral-matrix/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "spiral-matrix"
 version = "1.1.0"
 
diff --git a/exercises/spiral-matrix/tests/spiral-matrix.rs b/exercises/spiral-matrix/tests/spiral-matrix.rs
index f3abdfdde..6182ee569 100644
--- a/exercises/spiral-matrix/tests/spiral-matrix.rs
+++ b/exercises/spiral-matrix/tests/spiral-matrix.rs
@@ -1,4 +1,3 @@
-extern crate spiral_matrix;
 use spiral_matrix::*;
 
 #[test]
diff --git a/exercises/sublist/Cargo.toml b/exercises/sublist/Cargo.toml
index 7f04d9d8f..7b11434d1 100644
--- a/exercises/sublist/Cargo.toml
+++ b/exercises/sublist/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "sublist"
 version = "0.0.0"
diff --git a/exercises/sublist/tests/sublist.rs b/exercises/sublist/tests/sublist.rs
index eb02edc5d..87390a327 100644
--- a/exercises/sublist/tests/sublist.rs
+++ b/exercises/sublist/tests/sublist.rs
@@ -1,5 +1,3 @@
-extern crate sublist;
-
 use sublist::{sublist, Comparison};
 
 #[test]
diff --git a/exercises/sum-of-multiples/Cargo.toml b/exercises/sum-of-multiples/Cargo.toml
index 715333e01..a00645901 100644
--- a/exercises/sum-of-multiples/Cargo.toml
+++ b/exercises/sum-of-multiples/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "sum-of-multiples"
 version = "1.5.0"
diff --git a/exercises/sum-of-multiples/tests/sum-of-multiples.rs b/exercises/sum-of-multiples/tests/sum-of-multiples.rs
index d66f20396..1e64646f1 100644
--- a/exercises/sum-of-multiples/tests/sum-of-multiples.rs
+++ b/exercises/sum-of-multiples/tests/sum-of-multiples.rs
@@ -1,5 +1,3 @@
-extern crate sum_of_multiples;
-
 use sum_of_multiples::*;
 
 #[test]
diff --git a/exercises/tournament/Cargo.toml b/exercises/tournament/Cargo.toml
index d20c2e93a..b1e61cea3 100644
--- a/exercises/tournament/Cargo.toml
+++ b/exercises/tournament/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "tournament"
 version = "1.4.0"
diff --git a/exercises/tournament/tests/tournament.rs b/exercises/tournament/tests/tournament.rs
index 22dfdec1f..649256040 100644
--- a/exercises/tournament/tests/tournament.rs
+++ b/exercises/tournament/tests/tournament.rs
@@ -1,4 +1,4 @@
-extern crate tournament;
+use tournament;
 
 #[test]
 fn just_the_header_if_no_input() {
diff --git a/exercises/triangle/Cargo.toml b/exercises/triangle/Cargo.toml
index 3e3773889..4042a35b4 100644
--- a/exercises/triangle/Cargo.toml
+++ b/exercises/triangle/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "triangle"
 version = "0.0.0"
 
diff --git a/exercises/triangle/tests/triangle.rs b/exercises/triangle/tests/triangle.rs
index fe4e0dfc6..87e69defc 100644
--- a/exercises/triangle/tests/triangle.rs
+++ b/exercises/triangle/tests/triangle.rs
@@ -1,5 +1,3 @@
-extern crate triangle;
-
 use triangle::*;
 
 #[test]
diff --git a/exercises/two-bucket/Cargo.toml b/exercises/two-bucket/Cargo.toml
index a32a8744c..79a5c77b3 100644
--- a/exercises/two-bucket/Cargo.toml
+++ b/exercises/two-bucket/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "two-bucket"
 version = "1.4.0"
diff --git a/exercises/two-bucket/tests/two-bucket.rs b/exercises/two-bucket/tests/two-bucket.rs
index 365d489df..bd1ec1c15 100644
--- a/exercises/two-bucket/tests/two-bucket.rs
+++ b/exercises/two-bucket/tests/two-bucket.rs
@@ -1,5 +1,3 @@
-extern crate two_bucket;
-
 use two_bucket::{solve, Bucket, BucketStats};
 
 #[test]
diff --git a/exercises/two-fer/Cargo.toml b/exercises/two-fer/Cargo.toml
index c80ccc6a8..4f5f029ea 100644
--- a/exercises/two-fer/Cargo.toml
+++ b/exercises/two-fer/Cargo.toml
@@ -1,4 +1,5 @@
 [package]
+edition = "2018"
 name = "twofer"
 version = "1.2.0"
 
diff --git a/exercises/two-fer/tests/two-fer.rs b/exercises/two-fer/tests/two-fer.rs
index 3946d7c11..29196cfb0 100644
--- a/exercises/two-fer/tests/two-fer.rs
+++ b/exercises/two-fer/tests/two-fer.rs
@@ -1,4 +1,3 @@
-extern crate twofer;
 use twofer::twofer;
 
 #[test]
diff --git a/exercises/variable-length-quantity/Cargo.toml b/exercises/variable-length-quantity/Cargo.toml
index 7af4a7fe6..54173dea1 100644
--- a/exercises/variable-length-quantity/Cargo.toml
+++ b/exercises/variable-length-quantity/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "variable-length-quantity"
 version = "1.2.0"
diff --git a/exercises/variable-length-quantity/tests/variable-length-quantity.rs b/exercises/variable-length-quantity/tests/variable-length-quantity.rs
index c259a29ed..b2e3e7e29 100644
--- a/exercises/variable-length-quantity/tests/variable-length-quantity.rs
+++ b/exercises/variable-length-quantity/tests/variable-length-quantity.rs
@@ -1,4 +1,4 @@
-extern crate variable_length_quantity as vlq;
+use variable_length_quantity as vlq;
 
 #[test]
 fn to_single_byte() {
diff --git a/exercises/word-count/Cargo.toml b/exercises/word-count/Cargo.toml
index 57ab6b6e9..3d0b1c0e9 100644
--- a/exercises/word-count/Cargo.toml
+++ b/exercises/word-count/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "word-count"
 version = "1.2.0"
diff --git a/exercises/word-count/tests/word-count.rs b/exercises/word-count/tests/word-count.rs
index 2639033b1..4c57e0ca2 100644
--- a/exercises/word-count/tests/word-count.rs
+++ b/exercises/word-count/tests/word-count.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-extern crate word_count;
+use word_count;
 
 fn check_word_count(s: &str, pairs: &[(&str, u32)]) {
     // The reason for the awkward code in here is to ensure that the failure
@@ -38,19 +38,13 @@ fn test_count_multiple_occurrences() {
 #[test]
 #[ignore]
 fn cramped_lists() {
-    check_word_count(
-        "one,two,three",
-        &[("one", 1), ("two", 1), ("three", 1)],
-    );
+    check_word_count("one,two,three", &[("one", 1), ("two", 1), ("three", 1)]);
 }
 
 #[test]
 #[ignore]
 fn expanded_lists() {
-    check_word_count(
-        "one\ntwo\nthree",
-        &[("one", 1), ("two", 1), ("three", 1)],
-    );
+    check_word_count("one\ntwo\nthree", &[("one", 1), ("two", 1), ("three", 1)]);
 }
 
 #[test]
@@ -119,6 +113,6 @@ fn with_quotations() {
 fn multiple_spaces_not_detected_as_a_word() {
     check_word_count(
         " multiple   whitespaces",
-        &[("multiple", 1), ("whitespaces", 1)]
+        &[("multiple", 1), ("whitespaces", 1)],
     );
 }
diff --git a/exercises/wordy/Cargo.toml b/exercises/wordy/Cargo.toml
index 3dd5e2ff9..1138389d9 100644
--- a/exercises/wordy/Cargo.toml
+++ b/exercises/wordy/Cargo.toml
@@ -1,3 +1,4 @@
 [package]
+edition = "2018"
 name = "wordy"
 version = "1.5.0"
diff --git a/exercises/wordy/example.rs b/exercises/wordy/example.rs
index e4a089fb9..2717303a1 100644
--- a/exercises/wordy/example.rs
+++ b/exercises/wordy/example.rs
@@ -13,7 +13,9 @@ fn apply_op<'a, 'b>(num1: i32, words: &'a [Token<'b>]) -> Option<(i32, &'a [Toke
     let (op, num2) = op_and_num.split_at(number_pos);
     let num2 = match num2 {
         [Token::Number(i)] => i,
-        _ => unreachable!("We split at a Number above, so num2 is surely a single-element slice w/ a number"),
+        _ => unreachable!(
+            "We split at a Number above, so num2 is surely a single-element slice w/ a number"
+        ),
     };
     match op {
         [Token::NonNumber("plus")] => Some(num1 + num2),
@@ -21,26 +23,27 @@ fn apply_op<'a, 'b>(num1: i32, words: &'a [Token<'b>]) -> Option<(i32, &'a [Toke
         [Token::NonNumber("multiplied"), Token::NonNumber("by")] => Some(num1 * num2),
         [Token::NonNumber("divided"), Token::NonNumber("by")] => Some(num1 / num2),
         _ => None,
-    }.map(|n| (n, remainder))
+    }
+    .map(|n| (n, remainder))
 }
 
 pub fn answer(c: &str) -> Option<i32> {
-    let words = c.trim_end_matches('?').split_whitespace().map(|word| {
-        if let Ok(i) = word.parse::<i32>() {
-            Token::Number(i)
-        } else {
-            Token::NonNumber(word)
-        }
-    }).collect::<Vec<_>>();
+    let words = c
+        .trim_end_matches('?')
+        .split_whitespace()
+        .map(|word| {
+            if let Ok(i) = word.parse::<i32>() {
+                Token::Number(i)
+            } else {
+                Token::NonNumber(word)
+            }
+        })
+        .collect::<Vec<_>>();
     if words.len() < 3 {
         return None;
     }
     let mut result: i32 = match words[0..3] {
-        [
-            Token::NonNumber("What"),
-            Token::NonNumber("is"),
-            Token::Number(i),
-        ] => i,
+        [Token::NonNumber("What"), Token::NonNumber("is"), Token::Number(i)] => i,
         _ => return None,
     };
     let mut words = words.split_at(3).1;
diff --git a/exercises/wordy/tests/wordy.rs b/exercises/wordy/tests/wordy.rs
index 3052a3306..6e839487f 100644
--- a/exercises/wordy/tests/wordy.rs
+++ b/exercises/wordy/tests/wordy.rs
@@ -1,5 +1,3 @@
-extern crate wordy;
-
 use wordy::answer;
 
 #[test]