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.
Historically, arrays are the earliest known and most widespread of the complex data structures. Long ago, in FORTRAN, they were called subscripted variables. Today, they have changed somewhat, but the basic idea is the same in all languages. ...