Add Enumerable#to_h(&block)

crystal-lang · Dec 5, 2018 · 9863fca · 9863fca
1 parent 3021206
commit 9863fca
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diff --git a/spec/std/enumerable_spec.cr b/spec/std/enumerable_spec.cr
@@ -872,5 +872,9 @@ describe "Enumerable" do
     it "for array" do
       [[:a, :b], [:c, :d]].to_h.should eq({:a => :b, :c => :d})
     end
+
+    it "with block" do
+      (1..3).to_h { |i| {i, i ** 2} }.should eq({1 => 1, 2 => 4, 3 => 9})
+    end
   end
 end
diff --git a/src/enumerable.cr b/src/enumerable.cr
@@ -1291,4 +1291,14 @@ module Enumerable(T)
       hash[item[0]] = item[1]
     end
   end
+
+  # Creates a `Hash` out of an returned from a *block* Enumerable, where each
+  # element is a 2 element structure (for instance a `Tuple` or an `Array`).
+  #
+  # ```
+  # (1..3).to_h { |i| {i, i ** 2} } # => {1 => 1, 2 => 4, 3 => 9}
+  # ```
+  def to_h(&block : T -> U) forall U
+    map(&block).to_h
+  end
 end