I&#x27;m not 100% sure I agree with this as stated. Sure if the functionality is in core lib, use it but... it depends...<p>Consider these three statements:<p>- No code runs faster than no code.
- No code has fewer bugs than no code.
- No code is easier to understand than no code.<p>For a language like scala where there is no json processing in the standard lib, if there is a json library that is battle tested, then by removing my own json code and leaning on that well tried and tested code for serialization&#x2F;de-serialization, I&#x27;ve removed a whole bunch of code from my own library. The whole point of having modules as abstractions is to keep concerns neatly tucked in their own places to to increase re-use. By subscribing to the idea that my module should implement all of the functionality it needs, we&#x27;re loosing the benefits of modularization.<p>I just went through this exercise myself in a library I maintain - I removed my own json code and put a library in. I removed a bunch of code and made the whole thing simpler by leaning on that abstraction.