add closure and control-flow

Rust/rustifinity/challenges/closures.rs

@@ -0,0 +1,19 @@
+pub fn create_closures() -> (
+    impl Fn(i32, i32) -> i32,
+    impl Fn(i32, i32) -> i32,
+    impl Fn(i32, i32) -> i32,
+) {
+    let add_closure = |a, b| {
+        // Step 1: Implement here
+        a + b
+    };
+
+    // Step 2:
+    // Create the `subtract_closure` closure that subtracts two `i32` values.
+    let subtract_closure = |a, b| a - b;
+    // Step 3:
+    // Create the `multiply_closure` closure that multiplies two `i32` values.
+    let multiply_closure = |a, b| a * b;
+
+    (add_closure, subtract_closure, multiply_closure)
+}

Rust/rustifinity/challenges/control-flow.rs

@@ -0,0 +1,12 @@
+pub fn check_number_sign(number: i32) -> String {
+    // Return `"positive"` if the number is positive.
+    // Return `"negative"` if the number is negative.
+    // Return `"zero"` if the number is zero.
+    if number > 0 {
+        String::from("positive")
+    } else if number < 0 {
+        String::from("negative")
+    } else {
+        String::from("zero")
+    }
+}