I think the ability to “just look up this code” is a demonstration of fluency—if your way of figuring out “what happens when I invoke this library function” is “read the source code”, that indicates that you are able to fluently read code.
That said, fluently reading code and fluently writing code are somewhat different skills, and the very best developers relative to their toolchain can do both with that toolchain.
I think the ability to “just look up this code” is a demonstration of fluency—if your way of figuring out “what happens when I invoke this library function” is “read the source code”, that indicates that you are able to fluently read code.
That said, fluently reading code and fluently writing code are somewhat different skills, and the very best developers relative to their toolchain can do both with that toolchain.