Commit graph

441 commits

Author SHA1 Message Date
volth c03d73c1cf
prim_map, prim_genList: no need to force function argument which will be stored in mkApp 2018-07-07 23:30:17 +00:00
volth 627e28ba33 prim_mapAttrs: `f' must be evaluated lazily to avoid infinite recursion 2018-07-06 21:52:54 +00:00
volth 1515c65616 prim_concatMap: no need to force value 2018-07-05 15:33:33 +00:00
volth e6bf1a79d7 prim_mapAttrs: must be lazy to avoid infinite recursion 2018-07-05 15:33:12 +00:00
volth 841747b0e6
prim_concatMap: allocate intermediate list on stack 2018-07-05 12:37:37 +00:00
volth ee218f99ca
primops.cc: fix comment 2018-07-05 11:58:15 +00:00
volth 403a76a18f lib.concatMap and lib.mapAttrs to be builtins 2018-07-05 02:54:09 +00:00
Eelco Dolstra 1672bcd230
Move evaluator-specific settings out of libstore 2018-05-30 13:29:50 +02:00
volth 6cc28c0589
add `mod' and bitwise builtins: camel-case function names 2018-05-16 10:52:19 +00:00
volth f3c090f91c
add mod' and bitwise builtins: remove mod' and shifts 2018-05-16 06:57:11 +00:00
volth 8a6a14e1f5 add `mod' and bitwise builtins 2018-05-12 16:50:39 +00:00
Shea Levy b37f5ae31d
isFunction: True on primops.
Fixes #2073
2018-04-17 14:33:12 -04:00
Shea Levy fd98fca7bb
Make prim_exec and prim_importNative available to plugins 2018-04-09 10:26:50 -04:00
Shea Levy cfdbfa6b2c
Catch more possible instances of passing NULL to memcpy.
Actually fixes #1976.
2018-03-14 23:53:43 -04:00
Shea Levy 14ca85688c
Actually fix nixDataDir in non-canonical path 2018-02-28 06:19:40 -05:00
Tuomas Tynkkynen 77e9e1ed91 libexpr: Fix prim_replaceStrings() to work on an empty source string
Otherwise, running e.g.

nix-instantiate --eval -E --strict 'builtins.replaceStrings [""] ["X"] "abc"'

would just hang in an infinite loop.

Found by afl-fuzz.

First attempt of this was reverted in e2d71bd186 because it caused
another infinite loop, which is fixed now and a test added.
2018-02-26 19:49:13 +02:00
Eelco Dolstra e2d71bd186
Revert "libexpr: Fix prim_replaceStrings() to work on an empty source string"
This reverts commit 4ea9707591.

It causes an infinite loop in Nixpkgs evaluation,
e.g. "nix-instantiate -A hello" hung.

PR #1886.
2018-02-21 15:35:28 +01:00
Tuomas Tynkkynen 4ea9707591 libexpr: Fix prim_replaceStrings() to work on an empty source string
Otherwise, running e.g.

nix-instantiate --eval -E --strict 'builtins.replaceStrings [""] ["X"] "abc"'

would just hang in an infinite loop.

Found by afl-fuzz.
2018-02-19 23:20:26 +02:00
Tuomas Tynkkynen 37264ed0ad libexpr: Avoid an unnecessary string copy in prim_derivationStrict 2018-02-17 16:54:21 +02:00
Tuomas Tynkkynen 66eeff3345 libexpr: Remove unnecessary drvName assignment in prim_derivationStrict
drvName is already assigned to the same value right at the start of the
function.
2018-02-17 16:54:21 +02:00
Tuomas Tynkkynen 7e0360504d libexpr: Optimize prim_derivationStrict by using more symbol comparisons 2018-02-17 16:54:21 +02:00
Tuomas Tynkkynen b8bed7da14 libexpr: Optimize prim_attrNames a bit
Instead of having lexicographicOrder() create a temporary sorted array
of Attr*:s and copying attr names from that, copy the attr names
first and then sort that.
2018-02-17 16:54:21 +02:00
Shea Levy b095c06139
Add splitVersion primop.
Fixes #1868.
2018-02-14 09:55:43 -05:00
Eelco Dolstra abe6be578b
Merge pull request #1816 from shlevy/add-path
Add path primop.
2018-02-07 13:32:35 +01:00
Shea Levy 69d82e5c58
Add path primop.
builtins.path allows specifying the name of a path (which makes paths
with store-illegal names now addable), allows adding paths with flat
instead of recursive hashes, allows specifying a filter (so is a
generalization of filterSource), and allows specifying an expected
hash (enabling safe path adding in pure mode).
2018-02-06 16:48:08 -05:00
Eelco Dolstra 43f8ef73c6
realiseContext(): Add derivation outputs to the allowed paths
This makes import-from-derivation work in restricted mode again.
2018-02-06 15:38:45 +01:00
Eelco Dolstra 0c95776c3e
Don't define builtins.{currentSystem,currentTime} in pure mode
This makes it easier to provide a default, e.g.

  system = builtins.currentSystem or "x86_64-linux";
2018-01-18 16:38:48 +01:00
Eelco Dolstra d8b4cfad82
Typo 2018-01-17 11:53:08 +01:00
Eelco Dolstra d4dcffd643
Add pure evaluation mode
In this mode, the following restrictions apply:

* The builtins currentTime, currentSystem and storePath throw an
  error.

* $NIX_PATH and -I are ignored.

* fetchGit and fetchMercurial require a revision hash.

* fetchurl and fetchTarball require a sha256 attribute.

* No file system access is allowed outside of the paths returned by
  fetch{Git,Mercurial,url,Tarball}. Thus 'nix build -f ./foo.nix' is
  not allowed.

Thus, the evaluation result is completely reproducible from the
command line arguments. E.g.

  nix build --pure-eval '(
    let
      nix = fetchGit { url = https://github.com/NixOS/nixpkgs.git; rev = "9c927de4b179a6dd210dd88d34bda8af4b575680"; };
      nixpkgs = fetchGit { url = https://github.com/NixOS/nixpkgs.git; ref = "release-17.09"; rev = "66b4de79e3841530e6d9c6baf98702aa1f7124e4"; };
    in (import (nix + "/release.nix") { inherit nix nixpkgs; }).build.x86_64-linux
  )'

The goal is to enable completely reproducible and traceable
evaluation. For example, a NixOS configuration could be fully
described by a single Git commit hash. 'nixos-rebuild' would do
something like

  nix build --pure-eval '(
    (import (fetchGit { url = file:///my-nixos-config; rev = "..."; })).system
  ')

where the Git repository /my-nixos-config would use further fetchGit
calls or Git externals to fetch Nixpkgs and whatever other
dependencies it has. Either way, the commit hash would uniquely
identify the NixOS configuration and allow it to reproduced.
2018-01-16 19:23:18 +01:00
Eelco Dolstra 74f75c8558
import, builtins.readFile: Handle diverted stores
Fixes #1791
2018-01-12 17:31:08 +01:00
Shea Levy 689b2783fc
Add hasContext primop 2018-01-02 12:25:14 -05:00
Eelco Dolstra cd532a9251
Fix filterSource 2017-10-31 16:18:32 +01:00
Eelco Dolstra 812e027e1d
Add option allowed-uris
This allows network access in restricted eval mode.
2017-10-30 12:41:49 +01:00
Eelco Dolstra f9686885be
enable-http2 -> http2 2017-10-30 11:00:59 +01:00
Eelco Dolstra 23ce4b3393
fetchTarball: Use "source" as the default name
This ensures that it produces the same output as fetchgit:

  $ nix eval --raw '(builtins.fetchgit https://github.com/NixOS/patchelf.git)'
  /nix/store/ghigrkw02l440g8vfxa9wj4c3zpfmw99-source

  $ nix eval --raw '(fetchTarball https://github.com/NixOS/patchelf/archive/master.tar.gz)'
  /nix/store/ghigrkw02l440g8vfxa9wj4c3zpfmw99-source
2017-10-30 10:22:58 +01:00
Eelco Dolstra 66ddbef754
fetchurl/fetchTarball: Respect name changes
The computation of urlHash didn't take the name into account, so
subsequent fetchurl calls with the same URL but a different name would
resolve to the same cached store path.
2017-10-30 10:22:58 +01:00
Eelco Dolstra 8191992c83
Bump language version 2017-10-25 15:18:37 +02:00
Eelco Dolstra 2d5b1b24bf
Pass lists/attrsets to bash as (associative) arrays 2017-10-25 13:01:50 +02:00
Nicolas B. Pierron b8867a0239 Add builtins.string function.
The function 'builtins.split' takes a POSIX extended regular expression
and an arbitrary string. It returns a list of non-matching substring
interleaved by lists of matched groups of the regular expression.

```nix
with builtins;
assert split "(a)b" "abc"      == [ "" [ "a" ] "c" ];
assert split "([ac])" "abc"    == [ "" [ "a" ] "b" [ "c" ] "" ];
assert split "(a)|(c)" "abc"   == [ "" [ "a" null ] "b" [ null "c" ] "" ];
assert split "([[:upper:]]+)" "  FOO   "
                               == [ "  " [ "FOO" ] "   " ];
```
2017-08-15 20:04:11 +00:00
Jörg Thalheim 2fd8f8bb99 Replace Unicode quotes in user-facing strings by ASCII
Relevant RFC: NixOS/rfcs#4

$ ag -l | xargs sed -i -e "/\"/s/’/'/g;/\"/s/‘/'/g"
2017-07-30 12:32:45 +01:00
Eelco Dolstra 1762b9616c Merge pull request #1428 from rimmington/clearer-regex-space-error
Clearer error message when regex exceeds space limit
2017-07-10 11:45:05 +02:00
Rhys 17bb00d378 Clearer error message when regex exceeds space limit 2017-07-10 09:35:53 +10:00
Eelco Dolstra c0015e87af
Support base-64 hashes
Also simplify the Hash API.

Fixes #1437.
2017-07-04 15:07:41 +02:00
Eelco Dolstra e46090edb1
builtins.match: Improve error message for bad regular expression
Issue #1331.
2017-05-17 11:58:01 +02:00
Eelco Dolstra b01d62285c
Improve progress indicator 2017-05-16 16:09:57 +02:00
Eelco Dolstra c05d9ae7a5
Disallow outputHash being null or an empty string
Fixes #1384.
2017-05-15 18:47:13 +02:00
Shea Levy 3ecb09a40a builtins.exec: Make the argument just a list 2017-03-31 11:58:41 -04:00
Shea Levy 0bb8db257d Add exec primop behind allow-unsafe-native-code-during-evaluation.
Execute a given program with the (optional) given arguments as the
user running the evaluation, parsing stdout as an expression to be
evaluated.

There are many use cases for nix that would benefit from being able to
run arbitrary code during evaluation, including but not limited to:

* Automatic git fetching to get a sha256 from a git revision
* git rev-parse HEAD
* Automatic extraction of information from build specifications from
  other tools, particularly language-specific package managers like
  cabal or npm
* Secrets decryption (e.g. with nixops)
* Private repository fetching

Ideally, we would add this functionality in a more principled way to
nix, but in the mean time 'builtins.exec' can be used to get these
tasks done.

The primop is only available when the
'allow-unsafe-native-code-during-evaluation' nix option is true. That
flag also enables the 'importNative' primop, which is strictly more
powerful but less convenient (since it requires compiling a plugin
against the running version of nix).
2017-03-30 08:04:21 -04:00
Shea Levy 93f863be96 Add option to disable import-from-derivation completely, even if the drv is already realized 2017-03-08 08:46:12 -05:00
Eelco Dolstra 6de33a9c67
Add support for passing structured data to builders
Previously, all derivation attributes had to be coerced into strings
so that they could be passed via the environment. This is lossy
(e.g. lists get flattened, necessitating configureFlags
vs. configureFlagsArray, of which the latter cannot be specified as an
attribute), doesn't support attribute sets at all, and has size
limitations (necessitating hacks like passAsFile).

This patch adds a new mode for passing attributes to builders, namely
encoded as a JSON file ".attrs.json" in the current directory of the
builder. This mode is activated via the special attribute

  __structuredAttrs = true;

(The idea is that one day we can set this in stdenv.mkDerivation.)

For example,

  stdenv.mkDerivation {
    __structuredAttrs = true;
    name = "foo";
    buildInputs = [ pkgs.hello pkgs.cowsay ];
    doCheck = true;
    hardening.format = false;
  }

results in a ".attrs.json" file containing (sans the indentation):

  {
    "buildInputs": [],
    "builder": "/nix/store/ygl61ycpr2vjqrx775l1r2mw1g2rb754-bash-4.3-p48/bin/bash",
    "configureFlags": [
      "--with-foo",
      "--with-bar=1 2"
    ],
    "doCheck": true,
    "hardening": {
      "format": false
    },
    "name": "foo",
    "nativeBuildInputs": [
      "/nix/store/10h6li26i7g6z3mdpvra09yyf10mmzdr-hello-2.10",
      "/nix/store/4jnvjin0r6wp6cv1hdm5jbkx3vinlcvk-cowsay-3.03"
    ],
    "propagatedBuildInputs": [],
    "propagatedNativeBuildInputs": [],
    "stdenv": "/nix/store/f3hw3p8armnzy6xhd4h8s7anfjrs15n2-stdenv",
    "system": "x86_64-linux"
  }

"passAsFile" is ignored in this mode because it's not needed - large
strings are included directly in the JSON representation.

It is up to the builder to do something with the JSON
representation. For example, in bash-based builders, lists/attrsets of
string values could be mapped to bash (associative) arrays.
2017-01-26 20:40:33 +01:00
Eelco Dolstra 54801ed6ad
Bindings: Add a method for iterating in lexicographically sorted order 2017-01-26 20:40:33 +01:00
Eelco Dolstra 4e6a2fbc56
Revert "Propagate path context via builtins.readFile"
This reverts commit f7f0116dd7.

Issue #1174.
2017-01-24 15:31:54 +01:00
Eelco Dolstra fa738e50bc
Revert "builtins.readFile: Put the references of the file, not those needed to realize the file, into the context"
Reverting commit 451c223dee for now
because it breaks http://hydra.nixos.org/build/46805136, not clear
why.
2017-01-24 15:29:46 +01:00
Shea Levy 451c223dee builtins.readFile: Put the references of the file, not those needed to realize the file, into the context 2017-01-10 12:22:22 -05:00
Eelco Dolstra 215b70f51e
Revert "Get rid of unicode quotes (#1140)"
This reverts commit f78126bfd6. There
really is no need for such a massive change...
2016-11-26 00:38:01 +01:00
Guillaume Maudoux f78126bfd6 Get rid of unicode quotes (#1140) 2016-11-25 15:48:27 +01:00
Tuomas Tynkkynen f0fc3dd88b Fix SIGFPE from integer overflow during division
On some architectures (like x86_64 or i686, but not ARM for example)
overflow during integer division causes a crash due to SIGFPE.
Reproduces on a 64-bit system with:

    nix-instantiate --eval -E '(-9223372036854775807 - 1) / -1'

The only way this can happen is when the smallest possible integer is
divided by -1, so just special-case that.
2016-10-26 18:41:59 +03:00
Alexander Ried c935e8eeaf fixup! replace own regex class with std::regex 2016-10-19 16:03:53 +02:00
Alexander Ried b05b98df75 replace own regex class with std::regex 2016-10-18 20:22:25 +02:00
Eelco Dolstra c55bf085eb printMsg(lvlError, ...) -> printError(...) etc. 2016-09-21 16:54:53 +02:00
Eelco Dolstra 90ad02bf62 Enable HTTP/2 support
The binary cache store can now use HTTP/2 to do lookups. This is much
more efficient than HTTP/1.1 due to multiplexing: we can issue many
requests in parallel over a single TCP connection. Thus it's no longer
necessary to use a bunch of concurrent TCP connections (25 by
default).

For example, downloading 802 .narinfo files from
https://cache.nixos.org/, using a single TCP connection, takes 11.8s
with HTTP/1.1, but only 0.61s with HTTP/2.

This did require a fairly substantial rewrite of the Downloader class
to use the curl multi interface, because otherwise curl wouldn't be
able to do multiplexing for us. As a bonus, we get connection reuse
even with HTTP/1.1. All downloads are now handled by a single worker
thread. Clients call Downloader::enqueueDownload() to tell the worker
thread to start the download, getting a std::future to the result.
2016-09-14 16:36:02 +02:00
Eelco Dolstra c42d1acfeb forceBool(): Show position info 2016-08-29 19:37:19 +02:00
Eelco Dolstra 26d92017d3 Add builtin function "partition"
The implementation of "partition" in Nixpkgs is O(n^2) (because of the
use of ++), and for some reason was causing stack overflows in
multi-threaded evaluation (not sure why).

This reduces "nix-env -qa --drv-path" runtime by 0.197s and memory
usage by 298 MiB (in non-Boehm mode).
2016-08-29 19:36:54 +02:00
Eelco Dolstra 22d6e31fc6 Add a mechanism for derivation attributes to reference the derivation's outputs
For example, you can now say:

  configureFlags = "--prefix=${placeholder "out"} --includedir=${placeholder "dev"}";

The strings returned by the ‘placeholder’ builtin are replaced at
build time by the actual store paths corresponding to the specified
outputs.

Previously, you had to work around the inability to self-reference by doing stuff like:

  preConfigure = ''
    configureFlags+=" --prefix $out --includedir=$dev"
  '';

or rely on ad-hoc variable interpolation semantics in Autoconf or Make
(e.g. --prefix=\$(out)), which doesn't always work.
2016-08-17 17:19:32 +02:00
Eelco Dolstra ac841a4679 Merge pull request #1031 from abbradar/replacestrings-context
Allow contexted strings in replaceStrings
2016-08-16 12:47:20 +02:00
Nikolay Amiantov f1b8dd43be Allow contexted strings in replaceStrings 2016-08-16 13:20:56 +03:00
Shea Levy d52d391164 builtins.fetch{url,tarball}: Allow name attribute 2016-08-15 07:37:11 -04:00
Eelco Dolstra ee22a91ab8 makeFixedOutputPath(): Drop superfluous HashType argument 2016-07-26 21:25:52 +02:00
Eelco Dolstra 06bbfb6004 builtins.{fetchurl,fetchTarball}: Support a sha256 attribute
Also, allow builtins.{fetchurl,fetchTarball} in restricted mode if a
hash is specified.
2016-07-26 21:16:52 +02:00
Eelco Dolstra 7850d3d279 Make the store directory a member variable of Store 2016-06-01 16:24:17 +02:00
Eelco Dolstra 6c75cf69c3 Cleanup: Remove singleton() 2016-05-04 16:16:53 +02:00
Eelco Dolstra 41633f9f73 Improved logging abstraction
This also gets rid of --log-type, since the nested log type isn't
useful in a multi-threaded situation, and nobody cares about the
"pretty" log type.
2016-04-25 19:18:45 +02:00
Eelco Dolstra 363f37d084 Make the search path lazier with non-fatal errors
Thus, -I / $NIX_PATH entries are now downloaded only when they are
needed for evaluation. An error to download an entry is a non-fatal
warning (just like non-existant paths).

This does change the semantics of builtins.nixPath, which now returns
the original, rather than resulting path. E.g., before we had

  [ { path = "/nix/store/hgm3yxf1lrrwa3z14zpqaj5p9vs0qklk-nixexprs.tar.xz"; prefix = "nixpkgs"; } ... ]

but now

  [ { path = "https://nixos.org/channels/nixos-16.03/nixexprs.tar.xz"; prefix = "nixpkgs"; } ... ]

Fixes #792.
2016-04-14 15:32:24 +02:00
Eelco Dolstra 12b257f045 Make primop registration pluggable
This way we don't have to put all primops in one giant file.
2016-04-14 12:50:01 +02:00
Nikolay Amiantov f7f0116dd7 Propagate path context via builtins.readFile 2016-03-04 14:04:51 +03:00
Eelco Dolstra e9c50064b5 Add an HTTP binary cache store
Allowing stuff like

  NIX_REMOTE=https://cache.nixos.org nix-store -qR /nix/store/x1p1gl3a4kkz5ci0nfbayjqlqmczp1kq-geeqie-1.1

or

  NIX_REMOTE=https://cache.nixos.org nix-store --export /nix/store/x1p1gl3a4kkz5ci0nfbayjqlqmczp1kq-geeqie-1.1 | nix-store --import
2016-02-29 18:15:20 +01:00
Eelco Dolstra b3e8d72770 Merge pull request #762 from ctheune/ctheune-floats
Implement floats
2016-02-12 12:49:59 +01:00
Eelco Dolstra c10c61449f Eliminate the "store" global variable
Also, move a few free-standing functions into StoreAPI and Derivation.

Also, introduce a non-nullable smart pointer, ref<T>, which is just a
wrapper around std::shared_ptr ensuring that the pointer is never
null. (For reference-counted values, this is better than passing a
"T&", because the latter doesn't maintain the refcount. Usually, the
caller will have a shared_ptr keeping the value alive, but that's not
always the case, e.g., when passing a reference to a std::thread via
std::bind.)
2016-02-04 14:28:26 +01:00
Eelco Dolstra 9aac1861f7 Fix some signedness warnings 2016-01-07 14:37:39 +01:00
Fabian Schmitthenner 39d1da7b51 Better error message
Also show types when nix cannot compare values of different types.
This is also more consistent since types are already shown when comparing values of the same not comparable type.
2016-01-05 14:13:54 +01:00
Vladimír Čunát 29c0199d5c manual: document builtins.functionArgs
The text is just a conversion of comment from src/libexpr/primops.cc
2016-01-05 13:29:17 +01:00
Christian Theune 14ebde5289 First hit at providing support for floats in the language. 2016-01-05 00:40:40 +01:00
Eelco Dolstra 76cc8e97a2 Add sort primop 2015-07-28 18:39:39 +02:00
Eelco Dolstra 50807f3dd5 Add primop genList
This can be used to implement functions like ‘imap’ (or for that
matter, ‘map’) without the quadratic complexity incurred by calling
‘++’ repeatedly.
2015-07-28 17:28:35 +02:00
Eelco Dolstra d6d5885c15 Add replaceStrings primop
This is a generalisation of replaceChars in Nixpkgs.
2015-07-24 15:32:24 +02:00
Eelco Dolstra 2e8fd4c5cd Add concatStringsSep as a primop
This fixes the quadratic behaviour of concatStrings/concatStringsSep
in Nixpkgs.
2015-07-24 02:38:09 +02:00
Eelco Dolstra b83801f8b3 Optimize small lists
The value pointers of lists with 1 or 2 elements are now stored in the
list value itself. In particular, this makes the "concatMap (x: if
cond then [(f x)] else [])" idiom cheaper.
2015-07-23 22:05:09 +02:00
Eelco Dolstra 14be783676 Add primops all and any
These are used thousands of times during NixOS evaluation, so it's
useful to speed them up.
2015-07-23 19:23:11 +02:00
Shea Levy 39e27a04b8 Importing derivations: Add name attribute to make a valid drv 2015-07-23 17:04:07 +02:00
Shea Levy 1ed55234d9 Allow derivations-as-srcs in the context of builtins.toFile files 2015-07-23 17:03:47 +02:00
Eelco Dolstra 61af14a921 Add foldl' primop 2015-07-23 17:03:02 +02:00
Eelco Dolstra 6bd2c7bb38 OCD: foreach -> C++11 ranged for 2015-07-17 20:13:56 +02:00
Eelco Dolstra c1323b53e3 Fix fetchurl/fetchTarball 2015-06-01 15:08:09 +02:00
Eelco Dolstra 1c88e100e7 readFile: Check against nul bytes 2015-06-01 15:07:42 +02:00
Eelco Dolstra 9451ef3731 Allow URLs in the Nix search path
E.g. to install "hello" from the latest Nixpkgs:

  $ nix-build '<nixpkgs>' -A hello -I nixpkgs=https://nixos.org/channels/nixpkgs-unstable/nixexprs.tar.xz

Or to install a specific version of NixOS:

  $ nixos-rebuild switch -I nixpkgs=63def04891.tar.gz
2015-05-05 17:09:42 +02:00
Eelco Dolstra 4ed2187377 Use cached result if there is a network error 2015-04-09 12:49:13 +02:00
Eelco Dolstra 1fc905ad4c Move curl stuff into a separate file 2015-04-09 12:12:50 +02:00
Eelco Dolstra c1f04fae35 Implement a TTL on cached fetchurl/fetchTarball results
This is because we don't want to do HTTP requests on every evaluation,
even though we can prevent a full redownload via the cached ETag. The
default is one hour.
2015-04-09 11:55:36 +02:00
Eelco Dolstra 60340ce3e2 Implement caching of fetchurl/fetchTarball results
ETags are used to prevent redownloading unchanged files.
2015-04-09 11:42:04 +02:00
Eelco Dolstra 000b5a000f Add fetchTarball builtin
This function downloads and unpacks the given URL at evaluation
time. This is primarily intended to make it easier to deal with Nix
expressions that have external dependencies. For instance, to fetch
Nixpkgs 14.12:

  with import (fetchTarball https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz) {};

Or to fetch a specific revision:

  with import (fetchTarball 2766a4b44e.tar.gz) {};

This patch also adds a ‘fetchurl’ builtin that downloads but doesn't
unpack its argument. Not sure if it's useful though.
2015-03-25 17:29:09 +01:00