1 files changed, 76 insertions, 0 deletions
diff --git a/bs5/universal/native/shared/JsMap.re b/bs5/universal/native/shared/JsMap.re
new file mode 100644
index 0000000..abf8cfc
--- /dev/null
+++ b/bs5/universal/native/shared/JsMap.re
@@ -0,0 +1,76 @@
+[@platform js]
+include {
+          type t('k, 'v);
+
+          [@mel.new] external make: unit => t('k, 'v) = "Map";
+
+          [@mel.send] [@mel.return nullable]
+          external get: (t('k, 'v), 'k) => option('v) = "get";
+
+          [@mel.send] external set: (t('k, 'v), 'k, 'v) => unit = "set";
+
+          [@mel.send] external delete: (t('k, 'v), 'k) => unit = "delete";
+
+          [@mel.send] external clear: t('k, 'v) => unit = "clear";
+
+          [@mel.send] external size: t('k, 'v) => int = "size";
+
+          [@mel.send] external has: (t('k, 'v), 'k) => bool = "has";
+
+          [@mel.send] external values: t('k, 'v) => array('v) = "values";
+
+          [@mel.send] external keys: t('k, 'v) => array('k) = "keys";
+
+          [@mel.send]
+          external entries: t('k, 'v) => array(('k, 'v)) = "entries";
+
+          [@mel.send]
+          external forEach: (t('k, 'v), ('k, 'v) => unit) => unit = "forEach";
+        };
+
+[@platform native]
+include {
+          type t('k, 'v) = {mutable entries: list(('k, 'v))};
+
+          let make = () => {entries: []};
+
+          let set = (map, k, v) => {
+            let rec update = entries =>
+              switch (entries) {
+              | [] => [(k, v)]
+              | [(k', _), ...rest] when k == k' => [(k, v), ...rest]
+              | [pair, ...rest] => [pair, ...update(rest)]
+              };
+            map.entries = update(map.entries);
+            map;
+          };
+
+          let get = (map, k) =>
+            map.entries
+            |> List.find_opt(((k', _)) => k == k')
+            |> Option.map(((_, v)) => v);
+
+          let delete = (map, k) => {
+            map.entries = List.filter(((k', _)) => k != k', map.entries);
+            map;
+          };
+
+          let clear = map => {
+            map.entries = [];
+            map;
+          };
+
+          let size = map => List.length(map.entries);
+
+          let has = (map, k) =>
+            List.exists(((k', _)) => k == k', map.entries);
+
+          let values = map => List.map(((_, v)) => v, map.entries);
+
+          let keys = map => List.map(((k, _)) => k, map.entries);
+
+          let entries = map => map.entries;
+
+          let forEach = (map, f) =>
+            List.iter(((k, v)) => f(v, k, map), map.entries);
+        };