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5 commits

Author SHA1 Message Date
Valentin Gagarin
e0c4a95611 antiquotation -> string interpolation
as proposed by @mkaito[1] and @tazjin[2] and discussed with @edolstra
and Nix maintainers

[1]: https://github.com/NixOS/nix.dev/pull/267#issuecomment-1270076332
[2]: https://github.com/NixOS/nix.dev/pull/267#issuecomment-1270201979

Co-authored-by: John Ericson <git@JohnEricson.me>
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
2023-01-02 14:38:57 +01:00
Guillaume Maudoux
a474425425 Fix lexer to support $' in multiline strings. 2017-05-01 01:15:40 +02:00
Eelco Dolstra
e7bdde981f * Regression test. 2008-02-05 13:25:18 +00:00
Eelco Dolstra
b42ef9c054 * Syntax to escape '', ${. 2007-12-06 10:20:58 +00:00
Eelco Dolstra
6d6c68c0d2 * Added a new kind of multi-line string literal delimited by two
single quotes.  Example (from NixOS):

    job = ''
      start on network-interfaces

      start script

        rm -f /var/run/opengl-driver
        ${if videoDriver == "nvidia"        
          then "ln -sf ${nvidiaDrivers} /var/run/opengl-driver"
          else if cfg.driSupport
          then "ln -sf ${mesa} /var/run/opengl-driver"
          else ""
        }

        rm -f /var/log/slim.log

      end script
    '';

  This style has two big advantages:

  - \, ' and " aren't special, only '' and ${.  So you get a lot less
    escaping in shell scripts / configuration files in Nixpkgs/NixOS.
    The delimiter '' is rare in scripts (and can usually be written as
    "").  ${ is also fairly rare.

    Other delimiters such as <<...>>, {{...}} and <|...|> were also
    considered but this one appears to have the fewest drawbacks
    (thanks Martin).

  - Indentation is intelligently stripped so that multi-line strings
    can follow the nesting structure of the containing Nix
    expression.  E.g. in the example above 6 spaces are stripped from
    the start of each line.  This prevents unnecessary indentation in
    generated files (which sometimes even breaks things).

  See tests/lang/eval-okay-ind-string.nix for some examples.
2007-11-30 16:48:45 +00:00