[dfan]

When I was a kid, I learned Pascal from a book. We didn't even have a PC at home (it was the 80s) but my mother was a college professor and had access to the mainframe there. I wrote out a whole program to run Conway's Game of Life on a bunch of notebook paper, and one day when I was off from school I came in and typed the whole thing in at a terminal. I ran the command to compile it, and it spit out hundreds of syntax errors. Then it was time to go home.

It was not an auspicious start to my career in computer science.

[kabdib]

That's how I learned C. I bought a copy of K&R, but didn't have access to a Unix system with a C compiler for about a month (when my new job started). I read the book and wrote out all the exercises in a notebook.

When it came time to try my code, I spent a while correcting some basic misconceptions that I had developed but that hadn't been corrected by an actual compiler.

[Radim]

> It was not an auspicious start to my career in computer science.

I'd argue the opposite!

Learning how to "run" code in your head, cover edge cases and invariants, is a great skill to practice. When I was at a hospital after a difficult operation, I used to write down pages and pages of C64 programs in my notebook, too :-)

Even if I never even typed all them out later, I like to think this made me a better programmer. It trains your brain in a way that REPL doesn't.

[pjmorris]

I sometimes worry that I've become REPL-dependent.