Implement Vector#map.

lib/hamster/vector.rb

@@ -84,6 +84,12 @@ def each(&block)
       nil
     end
 
+    def map(&block)
+      return self unless block_given?
+      reduce(EmptyVector) { |vector, item| vector.add(yield(item)) }
+    end
+    def_delegator :self, :map, :collect
+
     def filter
       return self unless block_given?
       reduce(EmptyVector) { |vector, item| yield(item) ? vector.add(item) : vector }

spec/hamster/list/grep_spec.rb

@@ -48,7 +48,7 @@
 
           before do
             @original = Hamster.list(*values)
-            @result = @original.grep(String) { |item| item.downcase }
+            @result = @original.grep(String, &:downcase)
           end
 
           it "preserves the original" do

spec/hamster/list/map_spec.rb

@@ -27,7 +27,7 @@
           describe "with a block" do
 
             before do
-              @result = @original.send(method) { |item| item.downcase }
+              @result = @original.send(method, &:downcase)
             end
 
             it "preserves the original" do

spec/hamster/set/grep_spec.rb

@@ -47,7 +47,7 @@
           end
 
           it "returns #{expected.inspect}" do
-            @list.grep(String) { |item| item.downcase }.should == Hamster.set(*expected)
+            @list.grep(String, &:downcase).should == Hamster.set(*expected)
           end
 
 

spec/hamster/set/map_spec.rb

@@ -30,7 +30,7 @@
         describe "with a block" do
 
           before do
-            @mapped = @original.send(method) { |item| item.downcase }
+            @mapped = @original.send(method, &:downcase)
           end
 
           it "preserves the original values" do

spec/hamster/vector/map_spec.rb

@@ -0,0 +1,64 @@
+require 'spec_helper'
+
+require 'hamster/vector'
+
+describe Hamster::Vector do
+
+  [:map, :collect].each do |method|
+
+    describe "##{method}" do
+
+      describe "when empty" do
+
+        before do
+          @original = Hamster.vector
+          @mapped = @original.send(method) {}
+        end
+
+        it "returns self" do
+          @mapped.should equal(@original)
+        end
+
+      end
+
+      describe "when not empty" do
+
+        before do
+          @original = Hamster.vector("A", "B", "C")
+        end
+
+        describe "with a block" do
+
+          before do
+            @mapped = @original.send(method, &:downcase)
+          end
+
+          it "preserves the original values" do
+            @original.should == Hamster.vector("A", "B", "C")
+          end
+
+          it "returns a new vector with the mapped values" do
+            @mapped.should == Hamster.vector("a", "b", "c")
+          end
+
+        end
+
+        describe "with no block" do
+
+          before do
+            @result = @original.send(method)
+          end
+
+          it "returns self" do
+            @result.should equal(@original)
+          end
+
+        end
+
+      end
+
+    end
+
+  end
+
+end