Nire Bryce

Introduction

In this post I plan to give an introduction to reversible programming languages, and some introduction to the programming language Rust. Then I will introduce my amalgamation of those two things, RRust. The overview I will give here is not going to be too deep, In the end, I will provide some articles which go deeper into it all. RRust was produced for my Master’s Thesis, so the recounting here goes into some details which may already be known to Rust users. Finally, any comments or questions are welcome and can be sent to blog@erk.dev.

Reversible Computing

Introduction
Reversible computing is the idea that you can for a given function f(x) := y you can generate the inverse function that takes the output and generates the input f^-1(y) := x. This of course could be done by hand, but we want to make a machine, here donoted by I, that can make the transformation of the code. That is that I(f) := f^-1. To generalize this a bit we can look at x and y as states and f as a function that goes from state x to state y, this is how we will look at it in the following chapters since we are going to model our functions as mutations to variables. So we want to generate the inverse function f^-1 that takes state y and mutates it to state x.

it uses :quit so you're like
exit

error[E0425]: cannot find value `exit` in this scope
 --> src/main.rs:4:1
[...]
help: consider importing this function:
use std::process::exit;

exit()

error[E0425]: cannot find function `exit` in this scope
 --> src/main.rs:4:1
[...]
help: consider importing this function:
use std::process::exit;

use std::process::exit;
exit()

error[E0277]: `fn(i32) -> ! {exit}` doesn't implement `Debug`

quit

error[E0425]: cannot find value `quit` in this scope

help

error[E0425]: cannot find value `quit` in this scope

help()

error[E0425]: cannot find function `help` in this scope

ctrl-z
   ~  ddgr "irust" quit
   ~  fg
:quit

• harm a handful of people, often badly (unlike 3mi)
• has huge outsized effect on the field
• preventable, if time was taken to put processes in place
• partially from bad UX/infrastructure (the light for 'elevator broken' is the one that 'meltdown immanent' is right next to)
• decision came down to like 3 guys in a groupchat because nothing stopped them