For transforming back between lists and attrsets, it makes sense to have
a quasi-inverse of `builtins.listToAttrs` available as a library
function.
Co-authored-by: Silvan Mosberger <github@infinisil.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
To maintain backwards compatibility, this can't be changed in the Nix language.
We can however ensure that the version Nixpkgs has the more intuitive behavior.
There are a number of different syntaxes used for attrset type
signatures in our doc strings, this change standardises upon one that
uses :: for specifying attribute type, and ; terminators to be
consistent with nix syntax. There are no bugs in the functions
themselves, just that different syntaxes may confuse new users.
If all the docs are auto-generated, it should be easier to convert
them to Commonmark.
Co-Authored-By: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-Authored-By: Silvan Mosberger <contact@infinisil.com>
This brings two benefits:
1. The complete list of collisions is printed in the whenever any colliding
attribute is accessed.
2. The sets are intersected using a C++ primitive, which runs in O(n) time
(intersecting pre-sorted lists) with small constants rather than interpreted
Nix code.
Thanks to @toonn for prompting this improvement.
- Eta reduce `mapAttrsRecursiveCond`, `foldAttrs`, `getAttrFromPath`.
- Modify `matchAttrs` to use `elemAt` instead of `head (tail xs)` to access
elements.
- Modify `matchAttrs` to use `any id` instead of `foldr and true`.
- Eta reduce formal arguments of `recursiveUpdate'.
- Access elements in `recursiveUpdateUntil` using `elemAt` and `head`
directly instead of `head (tail xs)` which copies a singleton unnecessarily.
(`elemAt` is used instead of `last` to save a primitive call to `length`,
this is possible because the 2-tuple structure is guranteed)
- Use `length` instead of comparison to empty list to save a copy.
the fix to extendDerivation in #140051 unwittingly worsened eval performance by
quite a bit. set elements alone needed over 1GB extra after the change, which
seems disproportionate to how small it was. if we flip the logic used to
determine which outputs to install around and keep a "this one exactly" flag in
the specific outputs instead of a "all of them" in the root we can avoid most
of that cost.
- Remove inheritance of `lists.fold` as it isn't used anywhere.
- Inherit `foldl'` for consistency as only `cartesianProductOfSets` explicitly
reference lib.
- Inline `foldr` to generate nested attrs instead of using `listToAttrs` and `tail`.
This makes the function available without having to evaluate the
Nixpkgs fix-point, making it available in a more natural way for
code that deals with multiple Nixpkgs invocations.
Its definition is coupled to Nix rather than Nixpkgs, so it will
feel right at home in lib.
Suppose I have a Gemfile like this:
source "https://rubygems.org"
gem "actioncable"
gem "websocket-driver", group: :test
The gemset.nix generated by Bundix 2.4.1 will set ActionCable's groups
to [ "default" ], and websocket-driver's to [ "test" ]. This means that
the generated bundlerEnv wouldn't include websocket-driver unless the
test group was included, even though it's required by the default group.
This is arguably a bug in Bundix (websocket-driver's groups should
probably be [ "default" "test" ] or just [ "default" ]), but there's no
reason bundlerEnv should omit dependencies even given such an input --
it won't necessarily come from Bundix, and it would be good for
bundlerEnv to do the right thing.
To fix this, filterGemset is now a recursive function, that adds
dependencies of gems in the group to the filtered gemset until it
stabilises on the gems that match the required groups, and all of their
recursive dependencies.
