add Set::to_json

Author: bobzhang

builtin/builtin.mbti

@@ -330,6 +330,7 @@ impl Set {
   size[K](Self[K]) -> Int
   symmetric_difference[K : Hash + Eq](Self[K], Self[K]) -> Self[K]
   to_array[K](Self[K]) -> Array[K]
+  to_json[X : ToJson](Self[X]) -> Json
   to_string[K : Show](Self[K]) -> String
   union[K : Hash + Eq](Self[K], Self[K]) -> Self[K]
 }

builtin/json.mbt

@@ -134,6 +134,14 @@ pub fn Map::to_json[K : Show, V : ToJson](self : Map[K, V]) -> Json {
   Object(object)
 }
 
+pub fn Set::to_json[X : ToJson](self : Set[X]) -> Json {
+  let array = []
+  for v in self {
+    array.push(v.to_json())
+  }
+  Array(array)
+}
+
 pub fn Option::to_json[T : ToJson](self : T?) -> Json {
   match self {
     None => Null

builtin/linked_hash_set_wbtest.mbt renamed to builtin/linked_hash_set_test.mbt

@@ -146,6 +146,15 @@ test "insert_and_grow" {
   }
   assert_eq!(m.size(), 10)
   assert_eq!(m.capacity(), 16)
+  @json.inspect!(m, content=["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"])
+}
+
+test "array unique via Set" {
+  let v = [1, 2, 3, 4, 5, 3, 2, 4, 5]
+  let h = Set::from_iter(v.iter())
+  let v = [..h]
+  // @json.inspect!([..h])
+  @json.inspect!(v, content=[1, 2, 3, 4, 5])
 }
 
 test "remove_and_shift_back" {