Updated rand_distr, fixed and updated rand. (#627)

The `rand` crate has been updated to version `0.8.0`, and has its code
samples updated.

The `rand_distr` crate has been updated to version `0.4.0`.

Cargo.toml

@@ -37,8 +37,8 @@ num_cpus = "1.8"
 percent-encoding = "2.1"
 petgraph = "0.4"
 postgres = "0.17.2"
-rand = "0.7.3"
-rand_distr = "0.2.2"
+rand = "0.8.0"
+rand_distr = "0.4.0"
 rayon = "1.0"
 regex = "1.0"
 reqwest = { version = "0.10", features = ["blocking", "json", "stream"] }

src/algorithms/randomness/rand-choose.md

@@ -16,7 +16,7 @@ fn main() {
 
     let password: String = (0..PASSWORD_LEN)
         .map(|_| {
-            let idx = rng.gen_range(0, CHARSET.len());
+            let idx = rng.gen_range(0..CHARSET.len());
             CHARSET[idx] as char
         })
         .collect();

src/algorithms/randomness/rand-passwd.md

@@ -13,6 +13,7 @@ fn main() {
     let rand_string: String = thread_rng()
         .sample_iter(&Alphanumeric)
         .take(30)
+        .map(char::from)
         .collect();
 
     println!("{}", rand_string);

src/algorithms/randomness/rand-range.md

@@ -9,8 +9,8 @@ use rand::Rng;
 
 fn main() {
     let mut rng = rand::thread_rng();
-    println!("Integer: {}", rng.gen_range(0, 10));
-    println!("Float: {}", rng.gen_range(0.0, 10.0));
+    println!("Integer: {}", rng.gen_range(0..10));
+    println!("Float: {}", rng.gen_range(0.0..10.0));
 }
 ```