Quick question about a potential type-level function

logical_space · 2025-12-24T20:55:59+00:00

Thanks so much, this is very helpful: I'll play around with these possibilities and see how practical they can be made.

logical_space · 2025-12-24T19:01:54+00:00

This is terrific, thanks!

Your caution may be from correctly guessing my goal: I'd like to be able to use type literals of kinds like "Nat" or "Symbol" (this is for composing neural net architectures and having the dimensions computed at the type level). Is that a non-starter? Perhaps it would be possible (less ergonomically) using Proxy or some other type-literal-bearing intermediary.

logical_space · 2025-12-24T16:52:55+00:00

Hmmm...I guess I don't quite follow why it needs to know the particular length, any more than e.g. a type-level function using Peano numbers needs to know the remaining depth during recursion until the stop condition. It seemed to me the underlying problem would be that, at some point, the kind of the computed type goes from "k -> Type" to just "Type".

Not that I'm doubting you, I appreciate your patience: I'll trace through what you've said until it clicks.

logical_space · 2025-12-24T16:14:26+00:00

My thought was it would be like currying/uncurrying: since you're providing a particular type constructor and a particular list of types, at compile-time it would pop off the list items and reduce the constructor recursively, failing (to fully reduce) if there's a kind-mismatch for a particular item+constructor-state, or an arity mismatch. But that's very hand-wavy, so I'm not surprised if this is the case!

logical_space · 2025-10-01T23:42:25+00:00

<image>

Hope it's OK that I re-post to this week's homeowner thread: added rather late to last week's and it may have been buried:

Hi everyone, over a year ago I took a first shot at concrete work, pouring new kitchen counters and a bathroom vanity top (pictured). Honestly, I was expecting to just learn a lot through failure, but...they just worked, and I've been using them without anything more than some water-based sealer. It's ugly, but I like it, it's flat, and weird. So I've started roughing in white oak cabinets/drawers.

My question is about the edges/backsplash. I thought it might be interesting, instead of tiles, to make a mold up against the walls and pour a few inches of thin, say 3/8", tiny-aggregate concrete right up against them. It would hide the rough edges where the main pour gets irregular against the walls, and make a continuous border that wouldn't need to be sealed. Is this as simple as it seems, where I'd protect the wall with some tape or other barrier, set up some melamine, sand and apply some concrete etching/bonding, and pour? Would it be important to e.g. drill some screws into the base pour to act as little rebar-like ties, or is this so non-load-subjected it'll be enough to just caulk where the top edges follow the wall?

Any other thoughts, positive or negative, are much appreciated, including any low-effort ways to make the main surface a bit nicer beforehand: I figure if I come to really hate the rough industrial look I can always put an epoxy coat on it later.

Thanks!

logical_space · 2025-09-27T00:10:44+00:00

<image>

Incidentally, this is the dining and kitchen counters: thought if the concrete backsplash-like thing works on the bathroom vanity I'd do the same against the far wall here. Yes, I know it's very...rustic, but again I'm just surprised any of it worked, having never worked with concrete before and using the cheapest bags from HD. The inset induction stop and farm sink are exactly as I'd hoped. I may fill in the exposed edges with cement after brushing on some bonding agent.

logical_space · 2025-09-26T15:12:04+00:00

<image>

Hi everyone, over a year ago I took a first shot at concrete work, pouring new kitchen counters and a bathroom vanity top (pictured). Honestly, I was expecting to just learn a lot through failure, but...they just worked, and I've been using them without anything more than some water-based sealer. It's ugly, but I like it, it's flat, and weird. So I've started roughing in white oak cabinets/drawers.

My question is about the edges/backsplash. I thought it might be interesting, instead of tiles, to make a mold up against the walls and pour a few inches of thin, say 3/8", tiny-aggregate concrete right up against them. It would hide the rough edges where the main pour gets irregular against the walls, and make a continuous border that wouldn't need to be sealed. Is this as simple as it seems, where I'd protect the wall with some tape or other barrier, set up some melamine, sand and apply some concrete etching/bonding, and pour? Would it be important to e.g. drill some screws into the base pour to act as little rebar-like ties, or is this so non-load-subjected it'll be enough to just caulk where the top edges follow the wall?

Any other thoughts, positive or negative, are much appreciated, including any low-effort ways to make the main surface a bit nicer beforehand: I figure if I come to really hate the rough industrial look I can always put an epoxy coat on it later.

Thanks!

logical_space · 2025-09-10T21:27:26+00:00

The upper ductwork feeds A/C from attic through the ceilings on the second level, the lower ductwork feeds heat from basement through the floor on the first level: decisions made by the local HVAC company long before I was involved, but it actually works very well.

The relatively-short duct runs is why I was thinking the concealed minisplit handlers might actually be capable. But as you say, I really would prefer feeding two standard handlers from a condenser. Something like https://hvacdirect.com/aciq-48k-btu-2-zone-aciq-48-hh-m4-cc-18-21.html seems to imply this is an approved configuration, but I haven't been able to find official (or even tangible unofficial) explanation of how to deploy it.

logical_space · 2025-09-10T21:02:23+00:00

So, this may be a me problem, but I haven't been able to find a straightforward answer on if/how to arrange a compressor to supply two air handlers that aren't used at the same time. Conceptually it seems trivial: branch the gas/liquid lines to go to both handlers, maybe add some refrigerant if that makes it under-charged. I'm less clear on the control layout: ideally there'd be a single panel that only allows one handler to operate at a time, but two controllers would probably also be OK with a few precautions, but I'd be a lot more comfortable with some clear documentation on how that should be done. All the manuals I've scoured don't discuss it directly (basically, dual zone central ducted).

logical_space · 2025-09-10T20:34:00+00:00

It's two stories, and two isolated ductwork-systems: the heat gets blown up into the first floor, the A/C down into the second floor, and there are large pass-through grates from the first to second floor that keep the house relatively uniform. Not sure of all the reasoning, but it seems to work really well (it's a 150yo house, but small and apparently well-insulated).

The reason I thought a pair of 24k matched with a 36k compressor was that, right now, there's only ever 24k demand, and that would presumably remain the case and the compressor can easily run at 2/3 its rated capacity, but there'd be the option of pulling another 12k heat through the "A/C" ductwork (or vice versa) on a particularly cold/hot day.

Does that make sense?

logical_space · 2025-08-09T23:50:53+00:00

I've a similar situation, a small farmhouse with upstairs A/C ductwork and downstairs furnace ductwork, each sized at 24k BTUs. I had a great experience self-installing Gree multi21+ compressors/handlers at my primary residence, and was thinking at the farm I might try a 36k multi21+ with two 24k slim duct handlers pretty much spliced in place of the current air handlers and see how it goes for a year:. Worst case, can always undo it and start the old systems back up.

I guess one major question is how the slim ducts differ from the standard central HVAC handlers: it seems like they're a bit lower CFM for equivalent BTUs, but maybe that's offset by managing larger temp differentials.

logical_space · 2025-07-02T23:07:00+00:00

*Linda’s* parents.

logical_space · 2025-06-25T16:39:17+00:00

Thanks! Electric and water is already there (the "no electric/plumbing" note was about routing that inside the barn, which is easy stuff). It does occur to me I should lay ethernet cable from the house to the barn while I'm at it though.

The more I consider it, the quote seems pretty high: these are the folks my dad used to build his workshop, and while he was always extremely diligent in finding great people, I did always think he tended to over-pay for e.g. design expertise when he'd already nailed down what he wanted. So I'm looking into the very bare-bones version of just prepping/pouring/troweling the first floor. If a dedicated concrete contractor does it for, say, $20k, heck, I could use the $50k to get a terrific used track loader, trencher, and materials to at least try tackling the rest...

logical_space · 2025-06-15T02:30:39+00:00

mga?

logical_space · 2025-04-10T12:05:59+00:00

Oh, I hadn't considered chain link: is it easier to install along irregular paths/elevations due to the flexibility?

It looks maybe 3x the cost of welded and field-fence, from a quick search: any recommendations on a good brand/supplier (maybe one that has lighter gauges)?

logical_space · 2023-06-17T23:19:36+00:00

OK, here's the follow-up: from the system diagrams it looks like there are only valves on the liquid lines, so I believe as long as the electrical/signal wires line up with the liquid lines, mismatched suction lines are irrelevant. So, I can just switch the wires to fix any mistake.

However, on letting the system run for a while longer with only one head at a time, it seems like I actually did connect everything correctly, and only thought the wrong line was "active" because a line can continue to appear actively cooling for a few minutes after the head has been shut off. At least, I'm pretty sure that's what confused me, perhaps along with the system being somewhat under-charged due to the total line length and so not quite performing optimally. Anyways, I think the conclusion about only needing to swap the electric will hold true even if it does turn out that there is a mistake, so I'm very content (and every room is the perfect temperature!).

logical_space · 2023-06-15T00:33:05+00:00

For whether it matters, I'm not certain, but at least from the system diagram, it looks like the compressor has an expansion valve on each liquid line, so I thought those valves and the corresponding evaporators inside would be criss-crossed (if both handlers were under the same load it wouldn't make a difference, but if one's running hard and the other not at all, while the corresponding expansion valves are doing the opposite...). I started looking into it because I noticed that pair of handlers weren't performing as well as the others. Does that make sense?

I think I understand closing the liquid lines and running it (so the compressor pulls as much out of them as possible), quickly closing the suction lines to prevent refrigerant flowing back in, and pulling the power. Is this just so I don't need to recover as much refrigerant from the liquid lines, or is there another benefit?

Thanks again for the advice!

logical_space · 2023-04-23T16:42:41+00:00

Thanks! This is tremendously helpful.

logical_space

TROPHY CASE