Add a new `file` fetcher type, which will fetch a plain file over
http(s), or from the local file.
Because plain `http(s)://` or `file://` urls can already correspond to
`tarball` inputs (if the path ends-up with a know archive extension),
the URL parsing logic is a bit convuluted in that:
- {http,https,file}:// urls will be interpreted as either a tarball or a
file input, depending on the extensions of the path part (so
`https://foo.com/bar` will be a `file` input and
`https://foo.com/bar.tar.gz` as a `tarball` input)
- `file+{something}://` urls will be interpreted as `file` urls (with
the `file+` part removed)
- `tarball+{something}://` urls will be interpreted as `tarball` urls (with
the `tarball+` part removed)
Fix#3785
Co-Authored-By: Tony Olagbaiye <me@fron.io>
The produced path is then allowed be imported or utilized elsewhere:
```
assert (43 == import (builtins.toFile "source" "43")); "good"
```
This will still fail on write-only stores.
Requested by ppepino on the Matrix:
https://matrix.to/#/!KqkRjyTEzAGRiZFBYT:nixos.org/$Tb32BS3rVE2BSULAX4sPm0h6CDewX2hClOTGzTC7gwM?via=nixos.org&via=matrix.org&via=nixos.dev
This adds a new command, :bl, which works like :b but also creates
a GC root symlink to the various derivation outputs.
ckie@cookiemonster ~/git/nix -> ./outputs/out/bin/nix repl
Welcome to Nix 2.6.0. Type :? for help.
nix-repl> :l <nixpkgs>
Added 16118 variables.
nix-repl> :b runCommand "hello" {} "echo hi > $out"
This derivation produced the following outputs:
./repl-result-out -> /nix/store/kidqq2acdpi05c4a9mlbg2baikmzik44-hello
[1 built, 0.0 MiB DL]
ckie@cookiemonster ~/git/nix -> cat ./repl-result-out
hi
nixpkgs can save a good bit of eval memory with this primop. zipAttrsWith is
used quite a bit around nixpkgs (eg in the form of recursiveUpdate), but the
most costly application for this primop is in the module system. it improves
the implementation of zipAttrsWith from nixpkgs by not checking an attribute
multiple times if it occurs more than once in the input list, allocates less
values and set elements, and just avoids many a temporary object in general.
nixpkgs has a more generic version of this operation, zipAttrsWithNames, but
this version is only used once so isn't suitable for being the base of a new
primop. if it were to be used more we should add a second primop instead.
This function is very useful in nixpkgs, but its implementation in Nix
itself is rather slow due to it requiring a lot of attribute set and
list appends.
