Data commit

Task/Apply-a-callback-to-an-array/Crystal/apply-a-callback-to-an-array-1.crystal

@@ -0,0 +1,7 @@
+values = [1, 2, 3]
+
+new_values = values.map do |number|
+  number * 2
+end
+
+puts new_values  #=> [2, 4, 6]

Task/Apply-a-callback-to-an-array/Crystal/apply-a-callback-to-an-array-2.crystal

@@ -0,0 +1,12 @@
+values = [1, 2, 3]
+
+def double(number)
+  number * 2
+end
+
+# the `->double(Int32)` syntax creates a proc from a function/method. argument types must be specified.
+# the `&proc` syntax passes a proc as a block.
+# combining the two passes a function/method as a block
+new_values = values.map &->double(Int32)
+
+puts new_values  #=> [2, 4, 6]