X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/c3cbdbbd2fff81d2509b22d614343e6ca0250c09..2d40516a8393db1f27bb822ff95c71a1a9c82537:/workspace/src/part01.rs

diff --git a/workspace/src/part01.rs b/workspace/src/part01.rs
index 8d1c8b6..be2c2d2 100644
--- a/workspace/src/part01.rs
+++ b/workspace/src/part01.rs
@@ -1 +1,74 @@
- 
+// Rust-101, Part 01: Expressions, Inherent methods
+// ================================================
+
+// For Rust to compile this file, make sure to enable the corresponding line
+// in `main.rs` before going on.
+
+
+// ## Expression-based programming
+fn sqr(i: i32) -> i32 { i * i }
+
+// Conditionals are also just expressions. This is comparable to the ternary `? :` operator
+// from languages like C.
+fn abs(i: i32) -> i32 { if i >= 0 { i } else { -i } }
+
+enum NumberOrNothing {
+    Number(i32),
+    Nothing
+}
+use self::NumberOrNothing::{Number,Nothing};
+fn number_or_default(n: NumberOrNothing, default: i32) -> i32 {
+    match n {
+        Nothing => default,
+        Number(n) => n,
+    }
+}
+
+// It is even the case that blocks are expressions, evaluating to the last expression they contain.
+fn compute_stuff(x: i32) -> i32 {
+    let y = { let z = x*x; z + 14 };
+    y*y
+}
+
+// Let us now refactor `vec_min`.
+fn vec_min(v: Vec<i32>) -> NumberOrNothing {
+    fn min_i32(a: i32, b: i32) -> i32 {
+        unimplemented!()
+    }
+
+    let mut min = Nothing;
+    for e in v {
+        unimplemented!()
+    }
+    min
+}
+
+// Now that's already much shorter! Make sure you can go over the code above and actually understand
+// every step of what's going on.
+
+// ## Inherent implementations
+impl NumberOrNothing {
+    fn print(self) {
+        match self {
+            Nothing => println!("The number is: <nothing>"),
+            Number(n) => println!("The number is: {}", n),
+        };
+    }
+}
+
+// With our refactored functions and methods, `main` now looks as follows:
+fn read_vec() -> Vec<i32> {
+    vec![18,5,7,2,9,27]
+}
+pub fn main() {
+    let vec = read_vec();
+    let min = vec_min(vec);
+    unimplemented!()
+}
+// You will have to replace `part00` by `part01` in the `main` function in
+// `main.rs` to run this code.
+
+// **Exercise 01.1**: Write a function `vec_sum` that computes the sum of all values of a `Vec<i32>`.
+
+// **Exercise 01.2**: Write a function `vec_print` that takes a vector and prints all its elements.
+