diff --git a/doc/manual/src/language/values.md b/doc/manual/src/language/values.md index 4eb1887fa..ddd55a47e 100644 --- a/doc/manual/src/language/values.md +++ b/doc/manual/src/language/values.md @@ -6,19 +6,60 @@ *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 `${` must be - escaped by prefixing them with a backslash (`\`). Newlines, carriage - returns and tabs can be written as `\n`, `\r` and `\t`, - respectively. - - You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation]. + The most common way is to enclose the string between double quotes, e.g., `"foo bar"`. + Strings can span multiple lines. + The results of other expressions can be included into a string by enclosing them in `${ }`, a feature known as [string interpolation]. [string interpolation]: ./string-interpolation.md - The second way to write string literals is as an *indented string*, - which is enclosed between pairs of *double single-quotes*, like so: + The following must be escaped to represent them within a string, by prefixing with a backslash (`\`): + + - Double quote (`"`) + + > **Example** + > + > ```nix + > "\"" + > ``` + > + > "\"" + + - Backslash (`\`) + + > **Example** + > + > ```nix + > "\\" + > ``` + > + > "\\" + + - Dollar sign followed by an opening curly bracket (`${`) – "dollar-curly" + + > **Example** + > + > ```nix + > "\${" + > ``` + > + > "\${" + + The newline, carriage return, and tab characters can be written as `\n`, `\r` and `\t`, respectively. + + A "double-dollar-curly" (`$${`) can be written literally. + + > **Example** + > + > ```nix + > "$${" + > ``` + > + > "$\${" + + String values are output on the terminal with Nix-specific escaping. + Strings written to files will contain the characters encoded by the escaping. + + The second way to write string literals is as an *indented string*, which is enclosed between pairs of *double single-quotes* (`''`), like so: ```nix '' @@ -40,18 +81,71 @@ "This is the first line.\nThis is the second line.\n This is the third line.\n" ``` - Note that the whitespace and newline following the opening `''` is - ignored if there is no non-whitespace text on the initial line. + > **Note** + > + > Whitespace and newline following the opening `''` is ignored if there is no non-whitespace text on the initial line. + + > **Warning** + > + > Prefixed tab characters are not stripped. + > + > > **Example** + > > + > > The following indented string is prefixed with tabs: + > > + > > '' + > > all: + > > @echo hello + > > '' + > > + > > "\tall:\n\t\t@echo hello\n" Indented strings support [string interpolation]. - Since `${` 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 - characters can be written as `''\n`, `''\r`, `''\t`, and `''\` - escapes any other character. + The following must be escaped to represent them in an indented string: + + - `$` is escaped by prefixing it with two single quotes (`''`) + + > **Example** + > + > ```nix + > '' + > ''$ + > '' + > ``` + > + > "$\n" + + - `''` is escaped by prefixing it with one single quote (`'`) + + > **Example** + > + > ```nix + > '' + > ''' + > '' + > ``` + > + > "''\n" + + These special characters are escaped as follows: + - Linefeed (`\n`): `''\n` + - Carriage return (`\r`): `''\r` + - Tab (`\t`): `''\t` + + `''\` escapes any other character. + + A "double-dollar-curly" (`$${`) can be written literally. + + > **Example** + > + > ```nix + > '' + > $${ + > '' + > ``` + > + > "$\${\n" Indented strings are primarily useful in that they allow multi-line string literals to follow the indentation of the enclosing Nix @@ -167,7 +261,7 @@ function and the fifth being a set. Note that lists are only lazy in values, and they are strict in length. -Elements in a list can be accessed using [`builtins.elemAt`](./builtins.md#builtins-elemAt). +Elements in a list can be accessed using [`builtins.elemAt`](./builtins.md#builtins-elemAt). ## Attribute Set