Merge "doc/manual: clarify documentation related to the $$
parser bug" into main
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commit
7b1abf8107
1 changed files with 12 additions and 9 deletions
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@ -7,13 +7,16 @@
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*Strings* can be written in three ways.
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*Strings* can be written in three ways.
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The most common way is to enclose the string between double quotes,
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The most common way is to enclose the string between double quotes,
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e.g., `"foo bar"`. Strings can span multiple lines. The special
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e.g., `"foo bar"`. Strings can span multiple lines. The backslash
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characters `"` and `\` and the character sequence `${` must be
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(`\`) can be used to escape characters: newlines, carriage returns
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escaped by prefixing them with a backslash (`\`). Newlines, carriage
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and tabs may be written as `\n`, `\r` and `\t` respectively; any
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returns and tabs can be written as `\n`, `\r` and `\t`,
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other characters can be preceded by a backslash to remove any
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respectively.
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special meaning they may have, like the special characters `"` and
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`\` and the character sequence `${`.
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You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation].
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You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation].
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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.
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To express a `$` character immediately followed by an interpolation, the former must be escaped.
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[string interpolation]: ./string-interpolation.md
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[string interpolation]: ./string-interpolation.md
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Note that the whitespace and newline following the opening `''` is
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Note that the whitespace and newline following the opening `''` is
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ignored if there is no non-whitespace text on the initial line.
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ignored if there is no non-whitespace text on the initial line.
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Indented strings support [string interpolation].
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Since `${` and `''` have special meaning in indented strings, you
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Since `${` and `''` have special meaning in indented strings, you
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need a way to quote them. `$` can be escaped by prefixing it with
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need a way to quote them. `$` can be escaped by prefixing it with
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`''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
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`''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
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by prefixing it with `'`, i.e., `'''`. `$` removes any special
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by prefixing it with `'`, i.e., `'''`. Linefeed, carriage-return and tab
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meaning from the following `$`. Linefeed, carriage-return and tab
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characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
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characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
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escapes any other character.
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escapes any other character.
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Indented strings support [string interpolation] using `${ }` the same way regular strings do.
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`$${` is interpreted literally in indented strings as well, so the `$` character must be escaped if it is to be followed by an interpolation.
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Indented strings are primarily useful in that they allow multi-line
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Indented strings are primarily useful in that they allow multi-line
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string literals to follow the indentation of the enclosing Nix
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string literals to follow the indentation of the enclosing Nix
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expression, and that less escaping is typically necessary for
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expression, and that less escaping is typically necessary for
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