Merge named tuples

spec/std/named_tuple_spec.cr

@@ -200,4 +200,15 @@ describe "NamedTuple" do
     tup = {a: 1, b: 'a'}
     tup.values.should eq({1, 'a'})
   end
+
+  it "merges two named tuples" do
+    tup1 = {a: 1, b: '2'}
+    tup2 = {c: 4, d: true}
+
+    merged_tup = tup1 + tup2
+    expected = {a: 1, b: '2', c: 4, d: true}
+
+    merged_tup.should eq(expected)
+    typeof(merged_tup).should eq(typeof(expected))
+  end
 end

src/named_tuple.cr

@@ -383,6 +383,19 @@ struct NamedTuple
     {% end %}
   end
 
+  # Returns a named tuple that contains *self*'s elements followed by *other*'s elements.
+  #
+  # ```
+  # tuple1 = {name: "Crystal"}
+  # tuple2 = {year: 2011}
+  # tuple3 = tuple1 + tuple2
+  # tuple3         # => {name: "Crystal", year: 2011}
+  # typeof(tuple3) # => {name: String, year: Int32}
+  # ```
+  def +(other : U)
+    self.class.new(**self, **other)
+  end
+
   private def first_key_internal
     i = 0
     keys[i]