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Merge "doc/manual: clarify documentation related to the $$ parser bug" into main

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alois31 2024-07-18 15:01:20 +00:00 committed by Gerrit Code Review
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doc/manual/src/language/values.md
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@ -7,13 +7,16 @@
*Strings* can be written in three ways.
The most common way is to enclose the string between double quotes,
e.g., `"foo bar"`. Strings can span multiple lines. The special
characters `"` and `\` and the character sequence `${` must be
escaped by prefixing them with a backslash (`\`). Newlines, carriage
returns and tabs can be written as `\n`, `\r` and `\t`,
respectively.
e.g., `"foo bar"`. Strings can span multiple lines. The backslash
(`\`) can be used to escape characters: newlines, carriage returns
and tabs may be written as `\n`, `\r` and `\t` respectively; any
other characters can be preceded by a backslash to remove any
special meaning they may have, like the special characters `"` and
`\` and the character sequence `${`.
You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation].
Due to a parser issue that has since come to be relied upon, the character sequence `$${` is interpreted literally and does not introduce an interpolation.
To express a `$` character immediately followed by an interpolation, the former must be escaped.
[string interpolation]: ./string-interpolation.md
@ -43,16 +46,16 @@
Note that the whitespace and newline following the opening `''` is
ignored if there is no non-whitespace text on the initial line.
Indented strings support [string interpolation].
Since `${` and `''` have special meaning in indented strings, you
need a way to quote them. `$` can be escaped by prefixing it with
`''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
by prefixing it with `'`, i.e., `'''`. `$` removes any special
meaning from the following `$`. Linefeed, carriage-return and tab
by prefixing it with `'`, i.e., `'''`. Linefeed, carriage-return and tab
characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
escapes any other character.
Indented strings support [string interpolation] using `${ }` the same way regular strings do.
`$${` is interpreted literally in indented strings as well, so the `$` character must be escaped if it is to be followed by an interpolation.
Indented strings are primarily useful in that they allow multi-line
string literals to follow the indentation of the enclosing Nix
expression, and that less escaping is typically necessary for