$ nix repl lib
Welcome to Nix version 2.0.2. Type :? for help.
Loading 'lib'...
Added 350 variables.
-- this is the exact example from the function's documentation:
nix-repl> recursiveUpdateUntil (path: l: r: path == ["foo"]) {
# first attribute set
foo.bar = 1;
foo.baz = 2;
bar = 3;
} {
#second attribute set
foo.bar = 1;
foo.quz = 2;
baz = 4;
}
{ bar = 3; baz = 4; foo = { bar = 1; baz = 2; quz = 2; }; }
-- although the documentation says:
{
foo.bar = 1; # 'foo.*' from the second set
foo.quz = 2; #
bar = 3; # 'bar' from the first set
baz = 4; # 'baz' from the second set
}
This does break the API of being able to import any lib file and get
its libs, however I'm not sure people did this.
I made this while exploring being able to swap out docFn with a stub
in #2305, to avoid functor performance problems. I don't know if that
is going to move forward (or if it is a problem or not,) but after
doing all this work figured I'd put it up anyway :)
Two notable advantages to this approach:
1. when a lib inherits another lib's functions, it doesn't
automatically get put in to the scope of lib
2. when a lib implements a new obscure functions, it doesn't
automatically get put in to the scope of lib
Using the test script (later in this commit) I got the following diff
on the API:
+ diff master fixed-lib
11764a11765,11766
> .types.defaultFunctor
> .types.defaultTypeMerge
11774a11777,11778
> .types.isOptionType
> .types.isType
11781a11786
> .types.mkOptionType
11788a11794
> .types.setType
11795a11802
> .types.types
This means that this commit _adds_ to the API, however I can't find a
way to fix these last remaining discrepancies. At least none are
_removed_.
Test script (run with nix-repl in the PATH):
#!/bin/sh
set -eux
repl() {
suff=${1:-}
echo "(import ./lib)$suff" \
| nix-repl 2>&1
}
attrs_to_check() {
repl "${1:-}" \
| tr ';' $'\n' \
| grep "\.\.\." \
| cut -d' ' -f2 \
| sed -e "s/^/${1:-}./" \
| sort
}
summ() {
repl "${1:-}" \
| tr ' ' $'\n' \
| sort \
| uniq
}
deep_summ() {
suff="${1:-}"
depth="${2:-4}"
depth=$((depth - 1))
summ "$suff"
for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do
if [ $depth -eq 0 ]; then
summ "$attr" | sed -e "s/^/$attr./"
else
deep_summ "$attr" "$depth" | sed -e "s/^/$attr./"
fi
done
}
(
cd nixpkgs
#git add .
#git commit -m "Auto-commit, sorry" || true
git checkout fixed-lib
deep_summ > ../fixed-lib
git checkout master
deep_summ > ../master
)
if diff master fixed-lib; then
echo "SHALLOW MATCH!"
fi
(
cd nixpkgs
git checkout fixed-lib
repl .types
)
The old forms presumably predates, or were made in ignorance of,
`let inherit`. This way is better style as the scoping as more lexical,
something which Nix can (or might already!) take advantage of.
The manuals are now evaluated with each derivation in `pkgs` (recursively)
replaced by a fake with path "\${pkgs.path.to.the.attribute}".
It isn't perfect, but it seems to cover a vast majority of use cases.
Caveat: even if the package is reached by a different means,
the path above will be shown and not e.g. `${config.services.foo.package}`.
As before, defaults created by `mkDefault` aren't displayed,
but documentation shouldn't (mostly) be a reason to use that anymore.
Note: t wouldn't be enough to just use `lib.mapAttrsRecursive`,
because derivations are also (special) attribute sets.
For example, this allows writing
nix.package = /nix/store/786mlvhd17xvcp2r4jmmay6jj4wj6b7f-nix-1.10pre4206_896428c;
Also, document types.package in the manual.
Also, when an option definition fails to type-check, print the file
name of the module in which the offending definition occurs, e.g.
error: user-thrown exception: The option value `boot.loader.grub.version' in `/etc/nixos/configuration.nix' is not a integer.
