first tuple test

.gitignore

@@ -1 +1 @@
-/target
+target

tuples/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "tuples"
+version = "0.1.0"

tuples/Cargo.toml

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+[package]
+name = "tuples"
+version = "0.1.0"
+authors = ["Jon Janzen <jonjanzen@me.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tuples/src/lib.rs

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+type PointVector = (f32, f32, f32, f32);
+
+fn tuple_x(tuple: PointVector) -> f32 {
+    tuple.0
+}
+
+fn tuple_y(tuple: PointVector) -> f32 {
+    tuple.1
+}
+
+fn tuple_z(tuple: PointVector) -> f32 {
+    tuple.2
+}
+
+fn tuple_is_point(tuple: PointVector) -> bool {
+    tuple.3 == 1.0
+}
+fn tuple_is_vector(tuple: PointVector) -> bool {
+    tuple.3 == 0.0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn get_point() {
+        let tuple = (4.3, -4.2, 3.1, 1.0);
+
+        assert_eq!( 4.3,  tuple_x(tuple));
+        assert_eq!(-4.2,  tuple_y(tuple));
+        assert_eq!( 3.1,  tuple_z(tuple));
+        assert_eq!(true,  tuple_is_point(tuple));
+        assert_eq!(false, tuple_is_vector(tuple));
+    }
+
+    #[test]
+    fn get_vector() {
+        let tuple = (4.3, -4.2, 3.1, 0.0);
+
+        assert_eq!( 4.3,  tuple_x(tuple));
+        assert_eq!(-4.2,  tuple_y(tuple));
+        assert_eq!( 3.1,  tuple_z(tuple));
+        assert_eq!(false, tuple_is_point(tuple));
+        assert_eq!(true,  tuple_is_vector(tuple));
+    }
+}