paniq

The .bag File Format

A .bag file (short for "Blobby/Binary/Boxed/Bagged Atom Graph") file describes a directed graph of atoms, which can be either blob (array of bytes) or cell (array of atoms) in topological order of ownership, leaves first, root last. This renders the format particularly append/overlay-friendly, as the root can be rewritten without changing the existing file or removing unused nodes.

.bag is comparable to RIFF in scope but fixes two major problems with it, namely that RIFF can only encode trees and isn't topologically ordered, requiring the use of a stack when reading it.

The format can be read as a binary stream of 64-bit words. It begins with the magic 4-character sequence .bag and a 32-bit version which must be 1 (hence .bag\x01\0\0\0 or 0x000000016761622e), and is then only followed by atoms until the file ends.

An atom begins with a header word, followed by its contents, aligned t

raiph

Then mathematical neatness became a goal and led to pruning some features from the core of the language.

— John McCarthy, History of Lisp

If you prefer programming languages with a tidy and tiny core, you're in for a treat. This article drills down to the singleton primitive at the heart of Raku's metamodel ("model of a model") of a model of computation ("how units of computations, memories, and communications are organized")¹.

The reason I've written this article

It began with u/faiface's reddit post/thread "I'm impressed with Raku"². One of their sentences in particular stood out for me:

toroidal-code

Have you Hyper for Great Good

So. You have become an Emacs wizard. And you find yourself aching for the simplicity that another modifier key would introduce into your life. Ah, the things you could do with Hyper.

Or maybe, you just want Hyper for another reason.

... Except everywhere you look, everyone's talking about .xmodmaps and xkbcomp, but you're using one of those fancy desktop managers. (Aka, not awesome, dwm, xmonad or something even more hipster) And because of that, you're lost in the sea of confusion that is trying to customize your keyboard mapping.

Gnome, Cinnamon, and KDE all use xkb.