Automatically unpack Tuple when sorting arrays

Avoid capturing the block used for sorting, allowing automatic unpacking of Tuples. Since the block is only required in the inner `#quicksort!` function, this change gives some flexibility to the user allowing them write more expressive code. In the following example: a = [{"c", 3}, {"a", 1}, {"b", 2}] a.sort_by &.[1] a.sort_by { |(x, y)| y } Both `sort_by` calls produce the same result, one being more cryptic and the other being explicit about unpacking. In comparison: a.sort_by { |x, y| y } Produces the same results more transparently to the developer writing the code and behaves similar to other methods that perform automatic unpack like `#map` or `#each`. Performance-wise, this change does introduce a speedup on synthetic benchmarks: sort_by: 2.29M (± 1.03%) 1.10× slower sort_by (new): 2.51M (± 0.99%) fastest Fixes #3419
crystal-lang · Nov 16, 2016 · 7e62375 · 7e62375
1 parent 110b555
commit 7e62375
Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/spec/std/array_spec.cr b/spec/std/array_spec.cr
@@ -1029,6 +1029,13 @@ describe "Array" do
       b.should eq(["a", "foo", "hello"])
       a.should_not eq(b)
     end
+
+    it "unpacks tuple" do
+      a = [{"d", 4}, {"a", 1}, {"c", 3}, {"e", 5}, {"b", 2}]
+      b = a.sort_by { |x, y| y }
+      b.should eq([{"a", 1}, {"b", 2}, {"c", 3}, {"d", 4}, {"e", 5}])
+      a.should_not eq(b)
+    end
   end
 
   describe "sort_by!" do

diff --git a/src/array.cr b/src/array.cr
@@ -1494,11 +1494,11 @@ class Array(T)
   end
 
   def sort_by(&block : T -> _)
-    dup.sort_by! &block
+    dup.sort_by! { |e| yield(e) }
   end
 
   def sort_by!(&block : T -> _)
-    sorted = map { |e| {e, block.call(e)} }.sort! { |x, y| x[1] <=> y[1] }
+    sorted = map { |e| {e, yield(e)} }.sort! { |x, y| x[1] <=> y[1] }
     @size.times do |i|
       @buffer[i] = sorted.to_unsafe[i][0]
     end