Nix Language: Tips & Tricks: Difference between revisions
imported>Toraritte Moved from "Overview of Nix Expression Language" |
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== Finding the definition of a function or package == | == Finding the definition of a function or package == | ||
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</pre> | </pre> | ||
This doesn't work for non-functions or builtin functions, which show <code>«primop»</code>. It will always find the actual lambda, not an attribute that reexports a partial application, for example. | This doesn't work for non-functions or builtin functions, which show <code>«primop»</code>. It will always find the actual lambda, not an attribute that reexports a partial application, for example. | ||
Also in the REPL, you may use the <code>:edit</code> command (or its abbreviation <code>:e</code>) on an expression to open your editor (detected from the <code>$EDITOR</code> environment variable) at the location where an attribute was defined. | |||
<syntaxhighlight lang="bash"> | |||
$ nix repl --expr '{ pkgs = import <nixpkgs> { }; }' | |||
nix-repl> :e pkgs.lib.strings.makeBinPath | |||
</syntaxhighlight> | |||
The position information is not always perfectly accurate, but the above sequence of commands ''should'' open your editor to somewhere close to https://github.com/NixOS/nixpkgs/blob/b6ed1c5ee1470faf835024587c25fafb03693cbe/lib/strings.nix#L228. | |||
== Convert a string to an (<code>import</code>-able) path == | == Convert a string to an (<code>import</code>-able) path == | ||
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Note that this requires <code>./.</code> to refer to the current directory, but also importantly requires the leading slash on the quoted-string-path part. | Note that this requires <code>./.</code> to refer to the current directory, but also importantly requires the leading slash on the quoted-string-path part. | ||
== Writing update scripts / Referencing a relative path as string | == Writing update scripts / Referencing a relative path as string == | ||
Nix has relative path syntax that describes files relative to the current nix file, for example | Nix has relative path syntax that describes files relative to the current nix file, for example | ||
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in writeScript "update-foo.sh" '' | in writeScript "update-foo.sh" '' | ||
echo "updating foo.txt!" | echo "updating foo.txt!" | ||
echo "additional new data" >> ${lib.escapeShellArg textdata} | |||
'' | '' | ||
</syntaxHighlight> | </syntaxHighlight> | ||
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We can use this trick to update the sources of nix expressions (for example by generating a script which updates a json file with the software’s hashes). | We can use this trick to update the sources of nix expressions (for example by generating a script which updates a json file with the software’s hashes). | ||
[[Category: Nix | == Relevant pages == | ||
* [[Overview of the Nix Language]] | |||
* [[Editor Modes for Nix Files]] | |||
* [[Nix Expression Language: Learning resources|Learning resources]] | |||
[[Category: Nix Language]] | |||
[[Category: Cookbook]] | [[Category: Cookbook]] | ||