3 files changed, 59 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..0e68f71
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,3 @@
+mod volume;
+
+type Percent = u8;
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..e7a11a9
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}
diff --git a/src/volume.rs b/src/volume.rs
new file mode 100644
index 0000000..ea78938
--- /dev/null
+++ b/src/volume.rs
@@ -0,0 +1,53 @@
+use std::ops::Mul;
+
+trait Volume {
+    /// Returns the volume in SI units (cubic metres).
+    fn si(self) -> CubicMetre;
+}
+
+#[derive(Debug, PartialEq)]
+struct CubicMetre(f64);
+
+#[derive(Debug, PartialEq)]
+struct Litre(f64);
+
+impl Volume for Litre {
+    fn si(self) -> CubicMetre {
+        CubicMetre(self.0 * 10_f64.powf(-3.))
+    }
+}
+
+impl From<i32> for Litre {
+    fn from(value: i32) -> Self {
+        Self(value as f64)
+    }
+}
+
+impl From<CubicMetre> for Litre {
+    fn from(value: CubicMetre) -> Self {
+        Self(value.0 * 10_f64.powf(3.))
+    }
+}
+
+impl Mul<f64> for Litre {
+    type Output = Self;
+
+    fn mul(self, rhs: f64) -> Self::Output {
+        Self(self.0 * rhs)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::volume::{CubicMetre, Litre, Volume};
+
+    #[test]
+    fn litre_to_cubic_metre() {
+        assert_eq!(Litre(1000.).si(), CubicMetre(1.))
+    }
+
+    #[test]
+    fn cubic_metre_to_litre() {
+        assert_eq!(Litre::from(CubicMetre(1.)), Litre(1000.))
+    }
+}