Extensibility in programming language design

@inproceedings{Standish1975ExtensibilityIP,
  title={Extensibility in programming language design},
  author={T. Standish},
  booktitle={AFIPS '75},
  year={1975}
}
What is extensibility? What is it good for, if anything? Is it worth bothering about when designing a programming language? 
55 Citations
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