Reveal intent, hide implementation

When writing code, it's important to distinguish between INTENT (what is happening) and IMPLEMENTATION (how things work).

In the example below, intent is mixed with implementation:

users  .filter(user -> user.registrationDate.isBefore(dayjs().minus('years', 1)) && user.hasPurchases())  .filter(user -> authenticationService.isAuthenticated(user));

In order to understand WHAT this code is doing, your brain has to discern INTENT from IMPLEMENTATION. You need to spend 5-10 seconds on deliberate thinking. It consumes your limited and precious brainfuel. And that's only a single method.

Now, let's improve the code. Let's leave the intent visible, but implementation hidden:

users  .filter(isLoyal)  .filter(isAuthenticated);

It's immediately clear WHAT the code is doing. The code is not polluted with implementation details; details are hidden. Leaving only essential information and removing the noise is called abstraction. A well-abstracted code is easy to scan. A poorly abstracted code requires a lot of deliberate thinking and attention.

Remember: good code reveals intent, but hides implementation details until they are needed. Make the essence visible; hide the rest.

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