1 files changed, 100 insertions, 0 deletions
diff --git a/src/std/map_dict.gleam b/src/std/map_dict.gleam
new file mode 100644
index 0000000..32065f5
--- /dev/null
+++ b/src/std/map_dict.gleam
@@ -0,0 +1,100 @@
+import std/any
+import std/result
+import std/list
+
+pub external type MapDict(key, value);
+
+pub enum NotFound =
+  | NotFound
+
+pub external fn size(MapDict(k, v)) -> Int
+  = "maps" "size"
+
+pub external fn to_list(MapDict(key, value)) -> List({key, value})
+  = "maps" "to_list"
+
+pub external fn from_list(List({key, value})) -> MapDict(key, value)
+  = "maps" "from_list"
+
+external fn is_key(key, MapDict(key, v)) -> Bool
+  = "maps" "is_key"
+
+pub fn has_key(map, key) {
+  is_key(key, map)
+}
+
+pub external fn new() -> MapDict(key, value)
+  = "maps" "new"
+
+pub external fn fetch(MapDict(key, value), key) -> Result(value, NotFound)
+  = "gleam__stdlib" "map_fetch";
+
+external fn erl_put(key, value, MapDict(key, value)) -> MapDict(key, value)
+  = "maps" "put";
+
+pub fn put(map, key, value) {
+  erl_put(key, value, map)
+}
+
+external fn erl_map_values(fn(key, value) -> value, MapDict(key, value))
+  -> MapDict(key, value)
+  = "maps" "map";
+
+pub fn map_values(map, fun) {
+  erl_map_values(fun, map)
+}
+
+pub external fn keys(MapDict(keys, v)) -> List(keys)
+  = "maps" "keys"
+
+pub external fn values(MapDict(k, values)) -> List(values)
+  = "maps" "values"
+
+external fn erl_filter(fn(key, value) -> Bool, MapDict(key, value))
+  -> MapDict(key, value)
+  = "maps" "filter";
+
+pub fn filter(map, fun) {
+  erl_filter(fun, map)
+}
+
+external fn erl_take(List(k), MapDict(k, v)) -> MapDict(k, v) = "maps" "with"
+
+pub fn take(map, keys) {
+  erl_take(keys, map)
+}
+
+pub external fn merge(MapDict(k, v), MapDict(k, v)) -> MapDict(k, v) = "maps" "merge"
+
+external fn erl_delete(k, MapDict(k, v)) -> MapDict(k, v) = "maps" "remove"
+
+pub fn delete(map, key) {
+  erl_delete(key, map)
+}
+
+pub fn drop(map, keys) {
+  list:fold(keys, map, fn(key, acc) {
+    delete(acc, key)
+  })
+}
+
+pub external type NotFound;
+
+pub fn update(dict, key, f) {
+  case fetch(dict, key) {
+  | Ok(value) -> put(dict, key, f(Ok(value)))
+  | Error(_) -> put(dict, key, f(Error(NotFound)))
+  }
+}
+
+fn do_fold(list, acc, f) {
+  case list {
+    | [] -> acc
+    | [{k, v} | tail] -> do_fold(tail, f(k, v, acc), f)
+  }
+}
+
+pub fn fold(dict, acc, f) {
+  let kvs = to_list(dict)
+  do_fold(kvs, acc, f)
+}