Chapter 8. Arrays, Hashes, and Other Enumerables

All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can’t get them together again, there must be a reason. By all means, do not use a hammer.

—IBM maintenance manual (1925)

Simple variables are not adequate for real-life programming. Every modern language supports more complex forms of structured data and also provides mechanisms for creating new abstract data types.