Add assignment 8

src/assignments/assignment08.rs

@@ -0,0 +1,48 @@
+//! Assignment 8: First-class functions.
+//!
+//! The primary goal of this assignment is to get used to first-class functions.
+//!
+//! You should fill out the `todo!()` placeholders in such a way that `/scripts/grade-08.sh` works fine.
+//! See `assignment08_grade.rs` and `/scripts/grade-08.sh` for the test script.
+
+/// Returns an anonymous function that applies the given function `f` for `n` times.
+///
+/// For instance, `repeat(3, f)(x)` roughly translates to `f(f(f(x)))`.
+pub fn repeat<T, F: FnMut(T) -> T>(n: usize, mut f: F) -> impl FnMut(T) -> T {
+    todo!()
+}
+
+/// Applies the given function `f` for `i` times for the `i`-th element of the given vector.
+///
+/// For instance, `funny_map(f, [v0, v1, v2, v3])` roughly translates to `[v0, f(v1), f(f(v2)), f(f(f(v3)))]`.
+pub fn funny_map<T, F: Fn(T) -> T>(f: F, vs: Vec<T>) -> Vec<T> {
+    todo!()
+}
+
+/// Either `T1`, or `T2`.
+#[derive(Debug, PartialEq, Eq)]
+pub enum Either2<T1, T2> {
+    /// Case 1.
+    Case1 {
+        /// The inner value.
+        inner: T1,
+    },
+    /// Case 1.
+    Case2 {
+        /// The inner value.
+        inner: T2,
+    },
+}
+
+impl<T1, T2> Either2<T1, T2> {
+    /// Maps the inner value.
+    ///
+    /// If the inner value is case 1, apply `f1`, and if it is case 2, apply `f2`.
+    pub fn map<U1, U2, F1, F2>(self, f1: F1, f2: F2) -> Either2<U1, U2>
+    where
+        F1: FnOnce(T1) -> U1,
+        F2: FnOnce(T2) -> U2,
+    {
+        todo!()
+    }
+}