Pattern matching: checking values by their shape

What you learn in this lesson

• check for type, null, ranges and combinations of and, or and not with is
• write a switch expression with type patterns, when and the discard case _, and read the compiler’s messages about order and exhaustiveness
• check several properties of an object at once with property patterns
• take apart a program’s arguments with list patterns
• teach the Kladde commands on the command line, with exit code 2 for wrong input