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Eelco Dolstra
parent
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46 changed files with 1770 additions and 1155 deletions
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@ -51,7 +51,9 @@ For instance, `derivation` is also available as `builtins.derivation`.
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You can use `builtins` to test for the availability of features in
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the Nix installation, e.g.,
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if builtins ? getEnv then builtins.getEnv "PATH" else ""
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```nix
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if builtins ? getEnv then builtins.getEnv "PATH" else ""
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```
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This allows a Nix expression to fall back gracefully on older Nix
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installations that don’t have the desired built-in function.
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@ -114,9 +116,11 @@ For instance, `derivation` is also available as `builtins.derivation`.
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function is to obtain external Nix expression dependencies, such as
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a particular version of Nixpkgs, e.g.
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with import (fetchTarball https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz) {};
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stdenv.mkDerivation { … }
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```nix
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with import (fetchTarball https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz) {};
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stdenv.mkDerivation { … }
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```
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The fetched tarball is cached for a certain amount of time (1 hour
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by default) in `~/.cache/nix/tarballs/`. You can change the cache
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@ -124,19 +128,21 @@ For instance, `derivation` is also available as `builtins.derivation`.
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of seconds` or in the Nix configuration file with this option: `
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number of seconds to cache `.
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Note that when obtaining the hash with ` nix-prefetch-url
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` the option `--unpack` is required.
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Note that when obtaining the hash with ` nix-prefetch-url ` the
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option `--unpack` is required.
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This function can also verify the contents against a hash. In that
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case, the function takes a set instead of a URL. The set requires
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the attribute `url` and the attribute `sha256`, e.g.
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with import (fetchTarball {
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url = "https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz";
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sha256 = "1jppksrfvbk5ypiqdz4cddxdl8z6zyzdb2srq8fcffr327ld5jj2";
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}) {};
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stdenv.mkDerivation { … }
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```nix
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with import (fetchTarball {
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url = "https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz";
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sha256 = "1jppksrfvbk5ypiqdz4cddxdl8z6zyzdb2srq8fcffr327ld5jj2";
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}) {};
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stdenv.mkDerivation { … }
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```
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This function is not available if [restricted evaluation
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mode](../command-ref/conf-file.md) is enabled.
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@ -172,18 +178,22 @@ For instance, `derivation` is also available as `builtins.derivation`.
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- To fetch a private repository over SSH:
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builtins.fetchGit {
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url = "git@github.com:my-secret/repository.git";
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ref = "master";
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rev = "adab8b916a45068c044658c4158d81878f9ed1c3";
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}
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```nix
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builtins.fetchGit {
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url = "git@github.com:my-secret/repository.git";
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ref = "master";
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rev = "adab8b916a45068c044658c4158d81878f9ed1c3";
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}
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```
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- To fetch an arbitrary reference:
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builtins.fetchGit {
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url = "https://github.com/NixOS/nix.git";
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ref = "refs/heads/0.5-release";
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}
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```nix
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builtins.fetchGit {
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url = "https://github.com/NixOS/nix.git";
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ref = "refs/heads/0.5-release";
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}
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```
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- If the revision you're looking for is in the default branch of
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the git repository you don't strictly need to specify the branch
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@ -193,11 +203,13 @@ For instance, `derivation` is also available as `builtins.derivation`.
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branch for the non-default branch you will need to specify the
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the `ref` attribute as well.
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
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ref = "1.11-maintenance";
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}
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```nix
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
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ref = "1.11-maintenance";
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}
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```
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> **Note**
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>
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@ -211,24 +223,30 @@ For instance, `derivation` is also available as `builtins.derivation`.
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- If the revision you're looking for is in the default branch of
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the git repository you may omit the `ref` attribute.
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
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}
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```nix
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
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}
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```
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- To fetch a specific tag:
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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ref = "refs/tags/1.9";
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}
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```nix
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builtins.fetchGit {
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url = "https://github.com/nixos/nix.git";
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ref = "refs/tags/1.9";
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}
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```
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- To fetch the latest version of a remote branch:
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builtins.fetchGit {
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url = "ssh://git@github.com/nixos/nix.git";
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ref = "master";
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}
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```nix
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builtins.fetchGit {
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url = "ssh://git@github.com/nixos/nix.git";
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ref = "master";
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}
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```
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> **Note**
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>
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@ -248,10 +266,12 @@ For instance, `derivation` is also available as `builtins.derivation`.
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filtering certain files. For instance, suppose that you want to use
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the directory `source-dir` as an input to a Nix expression, e.g.
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stdenv.mkDerivation {
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...
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src = ./source-dir;
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}
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```nix
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stdenv.mkDerivation {
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...
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src = ./source-dir;
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}
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```
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However, if `source-dir` is a Subversion working copy, then all
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those annoying `.svn` subdirectories will also be copied to the
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@ -259,10 +279,10 @@ For instance, `derivation` is also available as `builtins.derivation`.
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causing lots of spurious rebuilds. With `filterSource` you can
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filter out the `.svn` directories:
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```
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src = builtins.filterSource
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(path: type: type != "directory" || baseNameOf path != ".svn")
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./source-dir;
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```nix
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src = builtins.filterSource
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(path: type: type != "directory" || baseNameOf path != ".svn")
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./source-dir;
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```
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Thus, the first argument *e1* must be a predicate function that is
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@ -279,10 +299,10 @@ For instance, `derivation` is also available as `builtins.derivation`.
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- `builtins.foldl’` *op* *nul* *list*
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Reduce a list by applying a binary operator, from left to right,
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e.g. `foldl’ op nul [x0 x1 x2 ...] = op (op
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(op nul x0) x1) x2) ...`. The operator is applied strictly, i.e.,
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its arguments are evaluated first. For example, `foldl’ (x: y: x +
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y) 0 [1 2 3]` evaluates to 6.
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e.g. `foldl’ op nul [x0 x1 x2 ...] = op (op (op nul x0) x1) x2)
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...`. The operator is applied strictly, i.e., its arguments are
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evaluated first. For example, `foldl’ (x: y: x + y) 0 [1 2 3]`
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evaluates to 6.
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- `builtins.functionArgs` *f*
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Return a set containing the names of the formal arguments expected
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@ -298,16 +318,19 @@ For instance, `derivation` is also available as `builtins.derivation`.
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- `builtins.fromJSON` *e*
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Convert a JSON string to a Nix value. For example,
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builtins.fromJSON ''{"x": [1, 2, 3], "y": null}''
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```nix
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builtins.fromJSON ''{"x": [1, 2, 3], "y": null}''
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```
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returns the value `{ x = [ 1 2 3 ]; y = null;
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}`.
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returns the value `{ x = [ 1 2 3 ]; y = null; }`.
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- `builtins.genList` *generator* *length*
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Generate list of size *length*, with each element *i* equal to the
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value returned by *generator* `i`. For example,
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builtins.genList (x: x * x) 5
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```nix
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builtins.genList (x: x * x) 5
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```
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returns the list `[ 0 1 4 9 16 ]`.
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@ -369,26 +392,34 @@ For instance, `derivation` is also available as `builtins.derivation`.
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variables that are in scope at the call site. For instance, if you
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have a calling expression
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rec {
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x = 123;
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y = import ./foo.nix;
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}
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```nix
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rec {
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x = 123;
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y = import ./foo.nix;
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}
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```
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then the following `foo.nix` will give an error:
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x + 456
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```nix
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x + 456
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```
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since `x` is not in scope in `foo.nix`. If you want `x` to be
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available in `foo.nix`, you should pass it as a function argument:
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rec {
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x = 123;
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y = import ./foo.nix x;
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}
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```nix
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rec {
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x = 123;
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y = import ./foo.nix x;
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}
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```
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and
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x: x + 456
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```nix
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x: x + 456
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```
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(The function argument doesn’t have to be called `x` in `foo.nix`;
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any name would work.)
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@ -442,23 +473,28 @@ For instance, `derivation` is also available as `builtins.derivation`.
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string-valued attribute `name` specifying the name of the attribute,
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and an attribute `value` specifying its value. Example:
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builtins.listToAttrs
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[ { name = "foo"; value = 123; }
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{ name = "bar"; value = 456; }
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]
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```nix
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builtins.listToAttrs
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[ { name = "foo"; value = 123; }
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{ name = "bar"; value = 456; }
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]
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```
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evaluates to
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{ foo = 123; bar = 456; }
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```nix
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{ foo = 123; bar = 456; }
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```
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- `map` *f* *list*; `builtins.map` *f* *list*
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Apply the function *f* to each element in the list *list*. For
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example,
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map (x: "foo" + x) [ "bar" "bla" "abc" ]
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```nix
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map (x: "foo" + x) [ "bar" "bla" "abc" ]
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```
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evaluates to `[ "foobar" "foobla" "fooabc"
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]`.
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evaluates to `[ "foobar" "foobla" "fooabc" ]`.
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- `builtins.match` *regex* *str*
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Returns a list if the [extended POSIX regular
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@ -466,19 +502,27 @@ For instance, `derivation` is also available as `builtins.derivation`.
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*regex* matches *str* precisely, otherwise returns `null`. Each item
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in the list is a regex group.
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builtins.match "ab" "abc"
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```nix
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builtins.match "ab" "abc"
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```
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Evaluates to `null`.
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builtins.match "abc" "abc"
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```nix
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builtins.match "abc" "abc"
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```
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Evaluates to `[ ]`.
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builtins.match "a(b)(c)" "abc"
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```nix
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builtins.match "a(b)(c)" "abc"
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```
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Evaluates to `[ "b" "c" ]`.
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builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" " FOO "
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```nix
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builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" " FOO "
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```
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Evaluates to `[ "foo" ]`.
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@ -534,11 +578,12 @@ For instance, `derivation` is also available as `builtins.derivation`.
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- `builtins.readDir` *path*
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Return the contents of the directory *path* as a set mapping
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directory entries to the corresponding file type. For instance, if
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directory `A` contains a regular file `B` and another directory `C`,
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then `builtins.readDir
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./A` will return the set
|
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directory `A` contains a regular file `B` and another directory
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`C`, then `builtins.readDir ./A` will return the set
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{ B = "regular"; C = "directory"; }
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```nix
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{ B = "regular"; C = "directory"; }
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```
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The possible values for the file type are `"regular"`,
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`"directory"`, `"symlink"` and `"unknown"`.
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@ -550,7 +595,9 @@ For instance, `derivation` is also available as `builtins.derivation`.
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Remove the attributes listed in *list* from *set*. The attributes
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don’t have to exist in *set*. For instance,
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removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]
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```nix
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removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]
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||||
```
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evaluates to `{ y = 2; }`.
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@ -558,7 +605,9 @@ For instance, `derivation` is also available as `builtins.derivation`.
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|||
Given string *s*, replace every occurrence of the strings in *from*
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with the corresponding string in *to*. For example,
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builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar"
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```nix
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builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar"
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```
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evaluates to `"fabir"`.
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||||
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|
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@ -572,10 +621,11 @@ For instance, `derivation` is also available as `builtins.derivation`.
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if the first element is less than the second, and `false` otherwise.
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For example,
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builtins.sort builtins.lessThan [ 483 249 526 147 42 77 ]
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```nix
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builtins.sort builtins.lessThan [ 483 249 526 147 42 77 ]
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||||
```
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||||
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||||
produces the list `[ 42 77 147 249 483 526
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]`.
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||||
produces the list `[ 42 77 147 249 483 526 ]`.
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||||
|
||||
This is a stable sort: it preserves the relative order of elements
|
||||
deemed equal by the comparator.
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||||
|
|
@ -587,19 +637,27 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
*regex* matches of *str*. Each item in the lists of matched
|
||||
sequences is a regex group.
|
||||
|
||||
builtins.split "(a)b" "abc"
|
||||
```nix
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||||
builtins.split "(a)b" "abc"
|
||||
```
|
||||
|
||||
Evaluates to `[ "" [ "a" ] "c" ]`.
|
||||
|
||||
builtins.split "([ac])" "abc"
|
||||
```nix
|
||||
builtins.split "([ac])" "abc"
|
||||
```
|
||||
|
||||
Evaluates to `[ "" [ "a" ] "b" [ "c" ] "" ]`.
|
||||
|
||||
builtins.split "(a)|(c)" "abc"
|
||||
```nix
|
||||
builtins.split "(a)|(c)" "abc"
|
||||
```
|
||||
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||||
Evaluates to `[ "" [ "a" null ] "b" [ null "c" ] "" ]`.
|
||||
|
||||
builtins.split "([[:upper:]]+)" " FOO "
|
||||
```nix
|
||||
builtins.split "([[:upper:]]+)" " FOO "
|
||||
```
|
||||
|
||||
Evaluates to `[ " " [ "FOO" ] " " ]`.
|
||||
|
||||
|
|
@ -623,7 +681,9 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
substring up to the end of the string is returned. *start* must be
|
||||
non-negative. For example,
|
||||
|
||||
builtins.substring 0 3 "nixos"
|
||||
```nix
|
||||
builtins.substring 0 3 "nixos"
|
||||
```
|
||||
|
||||
evaluates to `"nix"`.
|
||||
|
||||
|
|
@ -645,45 +705,47 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
“inline”. For instance, the following Nix expression combines the
|
||||
[Nix expression for GNU Hello](expression-syntax.md) and its
|
||||
[build script](build-script.md) into one file:
|
||||
|
||||
{ stdenv, fetchurl, perl }:
|
||||
|
||||
stdenv.mkDerivation {
|
||||
name = "hello-2.1.1";
|
||||
|
||||
builder = builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
|
||||
PATH=$perl/bin:$PATH
|
||||
|
||||
tar xvfz $src
|
||||
cd hello-*
|
||||
./configure --prefix=$out
|
||||
make
|
||||
make install
|
||||
";
|
||||
|
||||
src = fetchurl {
|
||||
url = "http://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz";
|
||||
sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
|
||||
};
|
||||
inherit perl;
|
||||
}
|
||||
|
||||
```nix
|
||||
{ stdenv, fetchurl, perl }:
|
||||
|
||||
stdenv.mkDerivation {
|
||||
name = "hello-2.1.1";
|
||||
|
||||
builder = builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
|
||||
PATH=$perl/bin:$PATH
|
||||
|
||||
tar xvfz $src
|
||||
cd hello-*
|
||||
./configure --prefix=$out
|
||||
make
|
||||
make install
|
||||
";
|
||||
|
||||
src = fetchurl {
|
||||
url = "http://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz";
|
||||
sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
|
||||
};
|
||||
inherit perl;
|
||||
}
|
||||
```
|
||||
|
||||
It is even possible for one file to refer to another, e.g.,
|
||||
|
||||
```
|
||||
builder = let
|
||||
configFile = builtins.toFile "foo.conf" "
|
||||
# This is some dummy configuration file.
|
||||
...
|
||||
";
|
||||
in builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
```nix
|
||||
builder = let
|
||||
configFile = builtins.toFile "foo.conf" "
|
||||
# This is some dummy configuration file.
|
||||
...
|
||||
cp ${configFile} $out/etc/foo.conf
|
||||
";
|
||||
```
|
||||
in builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
...
|
||||
cp ${configFile} $out/etc/foo.conf
|
||||
";
|
||||
```
|
||||
|
||||
Note that `${configFile}` is an
|
||||
[antiquotation](language-values.md), so the result of the
|
||||
|
|
@ -694,10 +756,12 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
It is however *not* allowed to have files mutually referring to each
|
||||
other, like so:
|
||||
|
||||
let
|
||||
foo = builtins.toFile "foo" "...${bar}...";
|
||||
bar = builtins.toFile "bar" "...${foo}...";
|
||||
in foo
|
||||
```nix
|
||||
let
|
||||
foo = builtins.toFile "foo" "...${bar}...";
|
||||
bar = builtins.toFile "bar" "...${foo}...";
|
||||
in foo
|
||||
```
|
||||
|
||||
This is not allowed because it would cause a cyclic dependency in
|
||||
the computation of the cryptographic hashes for `foo` and `bar`.
|
||||
|
|
@ -744,40 +808,42 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
|
||||
Here is an example where this is the case:
|
||||
|
||||
{ stdenv, fetchurl, libxslt, jira, uberwiki }:
|
||||
|
||||
stdenv.mkDerivation (rec {
|
||||
name = "web-server";
|
||||
|
||||
buildInputs = [ libxslt ];
|
||||
|
||||
builder = builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
mkdir $out
|
||||
echo "$servlets" | xsltproc ${stylesheet} - > $out/server-conf.xml ①
|
||||
";
|
||||
|
||||
stylesheet = builtins.toFile "stylesheet.xsl" ②
|
||||
"<?xml version='1.0' encoding='UTF-8'?>
|
||||
<xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
|
||||
<xsl:template match='/'>
|
||||
<Configure>
|
||||
<xsl:for-each select='/expr/list/attrs'>
|
||||
<Call name='addWebApplication'>
|
||||
<Arg><xsl:value-of select=\"attr[@name = 'path']/string/@value\" /></Arg>
|
||||
<Arg><xsl:value-of select=\"attr[@name = 'war']/path/@value\" /></Arg>
|
||||
</Call>
|
||||
</xsl:for-each>
|
||||
</Configure>
|
||||
</xsl:template>
|
||||
</xsl:stylesheet>
|
||||
";
|
||||
|
||||
servlets = builtins.toXML [ ③
|
||||
{ path = "/bugtracker"; war = jira + "/lib/atlassian-jira.war"; }
|
||||
{ path = "/wiki"; war = uberwiki + "/uberwiki.war"; }
|
||||
];
|
||||
})
|
||||
```nix
|
||||
{ stdenv, fetchurl, libxslt, jira, uberwiki }:
|
||||
|
||||
stdenv.mkDerivation (rec {
|
||||
name = "web-server";
|
||||
|
||||
buildInputs = [ libxslt ];
|
||||
|
||||
builder = builtins.toFile "builder.sh" "
|
||||
source $stdenv/setup
|
||||
mkdir $out
|
||||
echo "$servlets" | xsltproc ${stylesheet} - > $out/server-conf.xml ①
|
||||
";
|
||||
|
||||
stylesheet = builtins.toFile "stylesheet.xsl" ②
|
||||
"<?xml version='1.0' encoding='UTF-8'?>
|
||||
<xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
|
||||
<xsl:template match='/'>
|
||||
<Configure>
|
||||
<xsl:for-each select='/expr/list/attrs'>
|
||||
<Call name='addWebApplication'>
|
||||
<Arg><xsl:value-of select=\"attr[@name = 'path']/string/@value\" /></Arg>
|
||||
<Arg><xsl:value-of select=\"attr[@name = 'war']/path/@value\" /></Arg>
|
||||
</Call>
|
||||
</xsl:for-each>
|
||||
</Configure>
|
||||
</xsl:template>
|
||||
</xsl:stylesheet>
|
||||
";
|
||||
|
||||
servlets = builtins.toXML [ ③
|
||||
{ path = "/bugtracker"; war = jira + "/lib/atlassian-jira.war"; }
|
||||
{ path = "/wiki"; war = uberwiki + "/uberwiki.war"; }
|
||||
];
|
||||
})
|
||||
```
|
||||
|
||||
The builder is supposed to generate the configuration file for a
|
||||
[Jetty servlet container](http://jetty.mortbay.org/). A servlet
|
||||
|
|
@ -796,27 +862,29 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
configuration file for the Jetty server. The XML representation
|
||||
produced at point ③ by `toXML` is as follows:
|
||||
|
||||
<?xml version='1.0' encoding='utf-8'?>
|
||||
<expr>
|
||||
<list>
|
||||
<attrs>
|
||||
<attr name="path">
|
||||
<string value="/bugtracker" />
|
||||
</attr>
|
||||
<attr name="war">
|
||||
<path value="/nix/store/d1jh9pasa7k2...-jira/lib/atlassian-jira.war" />
|
||||
</attr>
|
||||
</attrs>
|
||||
<attrs>
|
||||
<attr name="path">
|
||||
<string value="/wiki" />
|
||||
</attr>
|
||||
<attr name="war">
|
||||
<path value="/nix/store/y6423b1yi4sx...-uberwiki/uberwiki.war" />
|
||||
</attr>
|
||||
</attrs>
|
||||
</list>
|
||||
</expr>
|
||||
```xml
|
||||
<?xml version='1.0' encoding='utf-8'?>
|
||||
<expr>
|
||||
<list>
|
||||
<attrs>
|
||||
<attr name="path">
|
||||
<string value="/bugtracker" />
|
||||
</attr>
|
||||
<attr name="war">
|
||||
<path value="/nix/store/d1jh9pasa7k2...-jira/lib/atlassian-jira.war" />
|
||||
</attr>
|
||||
</attrs>
|
||||
<attrs>
|
||||
<attr name="path">
|
||||
<string value="/wiki" />
|
||||
</attr>
|
||||
<attr name="war">
|
||||
<path value="/nix/store/y6423b1yi4sx...-uberwiki/uberwiki.war" />
|
||||
</attr>
|
||||
</attrs>
|
||||
</list>
|
||||
</expr>
|
||||
```
|
||||
|
||||
Note that we used the `toFile` built-in to write the builder and
|
||||
the stylesheet “inline” in the Nix expression. The path of the
|
||||
|
|
@ -830,13 +898,13 @@ For instance, `derivation` is also available as `builtins.derivation`.
|
|||
|
||||
- `builtins.tryEval` *e*
|
||||
Try to shallowly evaluate *e*. Return a set containing the
|
||||
attributes `success` (`true` if *e* evaluated successfully, `false`
|
||||
if an error was thrown) and `value`, equalling *e* if successful and
|
||||
`false` otherwise. Note that this doesn't evaluate *e* deeply, so
|
||||
` let e = { x = throw ""; }; in (builtins.tryEval e).success
|
||||
` will be `true`. Using ` builtins.deepSeq
|
||||
` one can get the expected result: `let e = { x = throw "";
|
||||
}; in (builtins.tryEval (builtins.deepSeq e e)).success` will be
|
||||
attributes `success` (`true` if *e* evaluated successfully,
|
||||
`false` if an error was thrown) and `value`, equalling *e* if
|
||||
successful and `false` otherwise. Note that this doesn't evaluate
|
||||
*e* deeply, so ` let e = { x = throw ""; }; in (builtins.tryEval
|
||||
e).success ` will be `true`. Using ` builtins.deepSeq ` one can
|
||||
get the expected result: `let e = { x = throw ""; }; in
|
||||
(builtins.tryEval (builtins.deepSeq e e)).success` will be
|
||||
`false`.
|
||||
|
||||
- `builtins.typeOf` *e*
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue