| 25 Oct 2025 |
 Katalin 🔪 | sure, hold on | 12:57:39 |
| Katalin 🔪 | https://git.dblsaiko.net/systems/tree/nixos/modules/sys2x/ssl.nix#n51 https://git.dblsaiko.net/systems/tree/configurations/whiprock/xmpp.nix#n15 | 13:07:18 |
 KFears (burnt out) | I've seen you use backpipes, but I can't parse how it works at all | 13:38:50 |
 Cyborus | Not to be confused with bagpipes | 13:40:09 |
| Katalin 🔪 | In reply to @kfears:matrix.org
I've seen you use backpipes, but I can't parse how it works at all essentially, they are equivalent to putting everything after them in parentheses, I think exactly like the haskell $ operator | 13:42:40 |
| Katalin 🔪 | or, if not exactly, it’s close enough at a glance. I don’t write haskell lol | 13:43:22 |
| Katalin 🔪 | yeah: https://wiki.haskell.org/$ | 13:44:36 |
| KFears (burnt out) | So like foo bar (baz queux) is foo bar |> baz queux? | 13:45:11 |
| KFears (burnt out) | But it only works with the last argument, because otherwise you still have to parenthesise? | 13:45:46 |
| Katalin 🔪 | <|, but yeah | 13:46:18 |
| Katalin 🔪 | adapting the example from the haskell wiki:
f <| g <| h x == f (g (h x))
f g h x == ((f g) h) x
| 13:47:57 |
 emily | <| is also more "order-of-eval-correct" | 13:48:41 |
| emily | (though (&) as flip ($) is also popular in Haskell – or was, back in my day…) | 13:48:52 |
| emily | (I personally avoided using $ in Haskell for various reasons so I have little opinion on any of this other than to say what I'd really like in Nix is function composition operators) | 13:49:29 |
| KFears (burnt out) | Interesting. Is it weird that I prefer parens? | 13:50:19 |
 K900 | ~~lib.pipe~~ | 13:50:28 |
| emily | parens can be ugly if you want something (x: …) (vs. something <| x: …) | 13:50:42 |
| Katalin 🔪 | In reply to @emilazy:matrix.org
parens can be ugly if you want something (x: …) (vs. something <| x: …) unfortunately the latter doesn’t actually parse right now :( | 13:51:05 |
| Katalin 🔪 | I would really like that | 13:51:12 |
| emily | in Haskell this often came up as
thingy = foopy $ do
…
as opposed to
thingy = foopy (do {
…
})
though they fixed it by just making foopy do work
| 13:51:27 |
| KFears (burnt out) | They are somewhat ugly, but they are universal, unlike the backpipe which only works on the last argument | 13:51:33 |
| emily | not sure if you could make f x: … work in Nix to mean f (x: …) | 13:51:36 |
| emily | heh, in Haskell again a niche but existing opinion was that a $ b c $ d e should parse as a (b c) (d e) rather than a (b c (d e)), because you can achieve the latter as a . b c $ d e using the function composition operator | 13:53:06 |
| emily | though of course Nix has no function composition operator so you'd have to turn it around into d e |> b c |> a | 13:53:28 |
 @dawnofmidnight:catgirl.cloud | would need parens anyway for the body in any case that's not like… constant or the identity function, so i don't think it'd be particularly useful? | 13:53:27 |
| emily | that is unfortunate and makes me think I'd never use <| | 13:53:46 |
| emily | hm, why? you do have to decide how foo = f x: x + 2; parenthesizes, but f (x: x + 2) seems like almost invariably what you'd want in practice | 13:54:22 |
| Katalin 🔪 | nix-repl> f <| x: x + 1
error: syntax error, expecting end of file
at «string»:1:7:
1| f <| x: x + 1
| ^
it seems like a bug to me
| 13:54:30 |
| Katalin 🔪 | but who knows | 13:54:38 |
| emily | in particular this would allow
stdenv.mkDerivation finalAttrs: {
…
}
| 13:54:40 |
