Do you guys memorize all this?

No.

• Sometimes you use your IDE to tell you what arguments you need and that puts you on the right track.

• Sometimes you look at the documentation. (I've looked at the same page of documentation countless times and docs.flutter.dev is always open if I'm using Flutter.)

• Sometimes you refer to old code of your own.

It's a waste of brain space to remember these things. Two years from now you might be doing things completely differently. You might be working with a different framework, your framework might simply evolve, or maybe the language you're working in suddenly adds sound null-safety *ehem* so basically all of your syntax changes overnight.

Internalize patterns and concepts. Not syntax.