Data commit

Task/Boolean-values/Mirah/boolean-values.mirah

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+import java.util.ArrayList
+import java.util.HashMap
+
+# booleans
+puts 'true is true' if true
+puts 'false is false' if (!false)
+
+# lists treated as booleans
+x = ArrayList.new
+puts "empty array is true" if x
+x.add("an element")
+puts "full array is true" if x
+puts "isEmpty() is false" if !x.isEmpty()
+
+# maps treated as booleans
+map = HashMap.new
+puts "empty map is true" if map
+map.put('a', '1')
+puts "full map is true" if map
+puts "size() is 0 is false" if !(map.size() == 0)
+
+# these things do not compile
+# value = nil   # ==> cannot assign nil to Boolean value
+# puts 'nil is false' if false == nil  # ==> cannot compare boolean to nil
+# puts '0 is false' if (0 == false)    # ==> cannot compare int to false
+
+#puts 'TRUE is true' if TRUE   # ==> TRUE does not exist
+#puts 'FALSE is false' if !FALSE   # ==> FALSE does not exist