Add basic roc_std Dict and Set implementations

crates/roc_std/src/roc_set.rs

@@ -0,0 +1,35 @@
+use crate::roc_dict::RocDict;
+use core::{
+    fmt::{self, Debug},
+    hash::Hash,
+};
+
+#[derive(Default, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct RocSet<T>(RocDict<T, ()>);
+
+impl<T> RocSet<T> {
+    #[allow(unused)]
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self(RocDict::with_capacity(capacity))
+    }
+
+    #[allow(unused)]
+    pub fn iter(&self) -> impl Iterator<Item = &T> {
+        self.0.iter_keys()
+    }
+}
+
+impl<T: Hash> RocSet<T> {
+    #[allow(unused)]
+    pub fn from_iter<I: Iterator<Item = T>>(src: I) -> Self {
+        Self(RocDict::from_iter(src.map(|elem| (elem, ()))))
+    }
+}
+
+impl<T: Debug> Debug for RocSet<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("RocSet ")?;
+
+        f.debug_set().entries(self.iter()).finish()
+    }
+}