To understand what I mean when I say that catlangs feel so unique, and that they are not, as people often say, the mirror image to Lisp, consider how traditional logic obfuscates resources and movement.
If your formula proves something from x, you can use x ten times, or zero times, it doesn’t matter. Logic is pretending that assumptions are inexhaustible, but programming systems don’t work like that, resources do matter. I don't say this to mean that copying a register is costing cycles, but that classical logic erases the fact of duplication. It's less about computational cost and more about semantics
In catlangs, assumptions are fuel, if you want two copies, you must actively duplicate it. It becomes an operation, not a ambient assumption. Jean-Yves Girard wrote extensively about this, and his insight was that this linear logic is closer to reality than classical logic is, it makes logic reflect process. Traditional logic is static, but he wanted a logic of change.
I see #Forth thrown left and right around #permacomputing circles on shaky notions of efficiency and human-scaleness, but I think what lies beneath, is this intuition that classical logic assumes infinite copyability. Which is unrealistic for memory, energy, time and just physical systems more generally. Linear logic, which lies at the heart of Forth, says that duplication is not free, erasure is not free, both must be explicit. This conservation law aligns logic with a finite natural world.
Programming languages typically hide duplication and lifetimes, or tack helpers on top as an afterthought. Values duplicate freely, things exist everywhere at once, names abstract away placement, this makes one's linguistic system spin, while the spatial system sleeps. My experience with catlang has has shifted programming from fussing with names and symbols to something like weaving. On this loom, things don't have names, just occupy spaces in a braid. If I had to guess, I'd say that probably triggers the same geometrically thinking part of the brain that tracks physical objects.
And that's the unique bit about catlangs!
I'm tempted to quote Perlis, but I'll abstain.
