The Tomorrow Corporation has built its own game programming stack with live reload, time travel debugging, and even the ability to serialise the entire game state and replay it between testers!

https://www.youtube.com/watch?v=72y2EC5fkcE

Do commas ever appear in idiomatic Clojure? It's syntactically legal but I don't think I've ever seen them in the wild.

Programming is a team activity: the vast majority of projects have multiple contributors. Yet all the films I've seen show a solo programmer at a keyboard.

Have any movies got this right?

Proper tail calls were added to the JS standard, but most implementations don't provide it. V8 even built it then removed it!

The concern is worse developer experience. An opt-in syntax has been proposed (cf loop/recur in Clojure) but no consensus.

https://www.mgmarlow.com/words/2021-03-27-proper-tail-calls-js/

You can also configure GitHub to include the logo in the social media preview. Hopefully this works:

https://github.com/Wilfred/difftastic

Taking a break from debugging graph traversal algorithms to give difftastic a logo :)

Difftastic update: I've rewritten the tree diffing logic to use Dijkstra's algorithm similar to Autochrome.

It works amazingly well! Note how it recognises both parent and children unchanged nodes in the lisp example. You can even see me refactoring Rust to use if-let.

Printers increasingly speak a standardised protocol, making it feasible to support printers without any drivers at all!

https://lwn.net/Articles/857502/

The test file is from https://fosdem.org/2021/schedule/event/sexpressiondiff/, which is a project exploring a pure-lisp solution to this problem.

How it works, roughly:

The parsing is inspired by Comby: everything is an atom or a list.

Tree diffing applies LCS diff at each level, then looks for subtrees that have moved.

Finally there's tons of futzing with line positions to print something comprehensible.

A little more progress on my syntactic differ: now it only shows lines of things that have changed!

Here's a Scheme example. Note that line 16 on the right has moved, but it's actually unchanged. Difftastic understands this :)

One thing that bothers me about today's diffs: we often read changes in a format that patch can consume!

Diffs are largely read by humans, but we have to mentally parse "@@ -40,7 +40,9 @@". Which line is line 40? Is it the first visible line, or the first changed line?

My syntactic diff tool basically works!

Diffing trees and printing them in a comprehensible way is extremely tricky. I'm hoping to get something I can release once I've hammered out the bugs.

WIP code is at https://github.com/wilfred/difftastic

This is really neat: an online collection of programs that can pass the type checker but fail at runtime, in a bunch of languages (Java, Scala, OCaml, Haskell, Rust): https://counterexamples.org/runtime-misinformation.html

It also discusses the design tradeoffs that led to these behaviours.

Python is discussing an elegant approach to tracebacks, where the subexpression that caused the exception is highlighted: https://www.python.org/dev/peps/pep-0657/

Why Lisp?

It has its pros and cons.