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Sender	Message	Time
26 Dec 2021
Xe	but yeah i was just doing things really wrongly with how i was copying things into my flake.nix	18:53:36
Xe	Download Screenshot from 2021-12-26 13-53-12.png	18:53:50
Xe	it works now 😀	18:53:54
28 Dec 2021
ilkecan	In reply to @andi:kack.it So, how do I write a flake that doesn't rebuild all the packages that have their source in the same repo (root) whenever I change a whitespace in my flake.nix? Is filterSource compatible/supported with flakes? You need to use nix-filter or something equivalent.	18:57:38
andi-	I wrote a filter expression that only accepted a single file. It still copied everything in the store.	18:58:26
ilkecan	In reply to @flyx:flyx.org hi folks! how can I prevent every edit of `flake.nix` to cause everything depending on `self` being rebuilt on the next `nix build`? `flake.nix` is checked into git so it is part of `self`, but obviously not part of the sources being built, so an edit should only affect those derivations whose definitions were changed by the edit please see the message above	18:58:27
ilkecan	In reply to @andi:kack.it I wrote a filter expression that only accepted a single file. It still copied everything in the store. The repo is copied to the Nix store before each evaluation but using nix-filter should prevent unnecessary rebuilds.	18:59:57
andi-	yeah but the former is the issue I am trying to avoid.	19:00:14
andi-	No point in copying everythin ginto the repo for just a few files..	19:00:22
ilkecan	You didn't say that in you original message. You asked how to write a flake that doesn't rebuild all packages not how to prevent Nix copying the full repo to the store.	19:02:15
29 Dec 2021
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30 Dec 2021
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flyx	I'm writing another article about Nix Flakes, and I'd like to write it in a way that enables me to automatically test whether the Nix code I show actually works. is there per chance someone else who did that and has a repo for it available where I can draw inspiration from?	19:13:22
flyx	In reply to @ilkecan:matrix.org You need to use nix-filter or something equivalent. when using nix-filter on `root = self;` it complains that `root` isn't a path. using `self.outPath` or `builtins.toPath self` doesn't work either.	20:50:34
ilkecan	In reply to @flyx:flyx.org when using nix-filter on `root = self;` it complains that `root` isn't a path. using `self.outPath` or `builtins.toPath self` doesn't work either. You can use `./.`	20:52:39
flyx	hmm, why do we have `self` then?	20:53:37
ilkecan	In reply to @flyx:flyx.org hmm, why do we have `self` then? `self` is an attribute set that has multiple attributes, one of them being `outPath`. In my experience, `self` is generally used to refer to the outputs of the current flake (e.g. `self.packages`). As for why `self` has an `outPath` attribute when we have `./.`; I am not sure whether `self.outPath` is required or better than `./.` for some cases but removing a possible edge case (all flake inputs except `self` has `outPath`) is enough of a reason for me. `nix-filter` expects `root` to be a Nix path but `self.outPath` is a string with context. While I don't know why that is necessary, one reason might be there was a bug in Nix that prevented filtering strings with context. But that should be possible now so the assertion in `nix-filter` might not be needed anymore.	21:59:12
ilkecan	In reply to @flyx:flyx.org hmm, why do we have `self` then? * `self` is an attribute set that has multiple attributes, one of them being `outPath`. In my experience, `self` is generally used to refer to the outputs of the current flake (e.g. `self.packages`). As for why `self` has an `outPath` attribute when we have `./.`; I am not sure whether `self.outPath` is required or better than `./.` for some cases but removing a possible edge case (all flake inputs except `self` has `outPath`) is enough of a reason for me. `nix-filter` expects `root` to be a Nix path but `self.outPath` is a string with context. While I am not sure why that assertion is necessary, one reason might be there was a bug in Nix that prevented filtering strings with context. But that should be possible now so the assertion in `nix-filter` might not be needed anymore.	22:00:04
tomberek	using self is generally preferred over ./.	22:01:17
tomberek	and at first it was unknown exactly what parts of storePath, path, filterSource, etc were safe, so we started with most of them not being allowed, and are slowly re-allowing them as we learn what can be done while retaining purity.	22:02:19
ilkecan	In reply to @tomberek:matrix.org using self is generally preferred over ./. Why is that?	22:03:16
ilkecan	Is it because of style or is there a difference between the two?	22:04:37
tomberek	i think it is more resilient when it comes to things like the name of the folder it happens to be in	22:07:15
ilkecan	Unless If I misunderstood you I don't think that is the case because both will refer to the same Nix store path in the form of `/nix/store/<hash>-source`. Since flake evaluation happens in the Nix store, possible impurity from the name of the root directory is avoided altogether.	22:13:31
ilkecan	In reply to @ilkecan:matrix.org `self` is an attribute set that has multiple attributes, one of them being `outPath`. In my experience, `self` is generally used to refer to the outputs of the current flake (e.g. `self.packages`). As for why `self` has an `outPath` attribute when we have `./.`; I am not sure whether `self.outPath` is required or better than `./.` for some cases but removing a possible edge case (all flake inputs except `self` has `outPath`) is enough of a reason for me. `nix-filter` expects `root` to be a Nix path but `self.outPath` is a string with context. While I am not sure why that assertion is necessary, one reason might be there was a bug in Nix that prevented filtering strings with context. But that should be possible now so the assertion in `nix-filter` might not be needed anymore. I think `lib.pathIsDirectory` can be used instead of `builtins.isPath` in that assertion.	22:41:48
31 Dec 2021
brendanzab	is there a way to check the flake schema somehow? I was running `nix flake check`, assuming it was checking the schema, but if seems like it let through a bug with how I'd defined my `apps`: https://github.com/brendanzab/ocaml-flake-example/pull/5/files	08:48:04
brendanzab	it only popped up when I ran `nix flake show` and got: `git+file:///.../ocaml-flake-example?ref=main&rev=840f7782276b4e1cc17c3baa3fae03247d188c78 ├───apps │ ├───aarch64-darwin error: not an app definition`	08:48:56
brendanzab	is seems like that produced an non-zero exit code though. should I be running `nix flake show` in CI?	08:50:00

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