## The Repl Since 1 is a programmer, 1's not super articulate in words, so for the first part of the book (before lost+found) 1 is mostly a supporting character and is mostly listening and learning, but the knowledge flows in one direction. In the two files: - lost+found/1/5 (the technical part of infinity and Cantor) - lost+found/2/5 (the technical part of logic and Russell) 0 starts to notice that 1 is extremely good at asking deep insightful questions _once things get technical._ 0 is super impressed by how deep 1's questions are about technical stuff. 1 insists they're not deep, she's just a programmer, and she just wants a repl. Since 1 grew up in the era of interpreted languages with interactive shells (as opposed to the older era of only compiled languages or the even older era of math) the idea is that she grew up expecting to be able to experiment with technical stuff and see how it works, because documentation is always crap even when it's good. We've established that 0 loves the shell. What we learn once we get to the technical dialogues in lost+found is that 1 needs a repl to feel like she understands something. A repl is the best teacher. So whenever they're doing cantor's infinity stuff or first order logic or lambda calculus or whatever, 1 keeps wanting a repl so she can interactively see wtf the books mean because she feels like the books are vague and unclear. Etc etc roughly this idea: 0: Most of the time I think you don't know anything 1: Hey! 0: No no, it's a compliment. 1: Didn't sound like one. 0: I was gonna say most of the time it doesn't seem like you know anythi--- 1: You don't need to say it again! 0: ---BUT once things get technical suddenly you seem like you know everything about this stuff--- 1: That's because I don't know anything about this stuff. I'm a developer. 0: No I mean once things get technical, suddenly you seem to know everything about this stuff that's missing or incompletely specified. 1: I just want a repl! 0: Exactly! Because you're always wanting a repl on things, you're able to see things no one else usually sees. 1: Is a repl so much to ask? 0 and 1 then agree at the end of lost+found/2/5 (right before we get to Church Gödel Turing) that when it's time for the technical stuff, 0 will act as 1's repl, and let her try things interactively while 1 says "ok" or "error: explanation of why." We eventually get: - a repl on infinity - a repl on logic - a repl on lambda calculus - a repl on general recursive functions (for this one she has basically no questions and just goes "yeah this is obvious," but then hears what Gödel's theorem actually says and gets mad because it's basically doing the same kind of thing she was told earlier isn't allowed: mixing the formal language and the informal meta language.) - a repl on turing's paper (for this one she also isn't particularly confused. once you have a repl on a turing machine you realize you're just using it to interactively write on paper, so the whole thing is pointless if it isn't automatic.)