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Diffstat (limited to 'doc/manual')
| -rw-r--r-- | doc/manual/src/language/index.md | 908 |
1 files changed, 542 insertions, 366 deletions
diff --git a/doc/manual/src/language/index.md b/doc/manual/src/language/index.md index 724484460..cc71c3143 100644 --- a/doc/manual/src/language/index.md +++ b/doc/manual/src/language/index.md @@ -20,370 +20,546 @@ manual](https://nixos.org/nix/manual/#chap-writing-nix-expressions) for the rest. <table> - <tr> - <th> - Example - </th> - <th> - Description - </th> - </tr> - <tr> - <td> - *Basic values* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `"hello world"` - </td> - <td> - A string - </td> - <td> - ``` - '' - multi - line - string - '' - ``` - </td> - <td> - A multi-line string. Strips common prefixed whitespace. Evaluates to `"multi\n line\n string"`. - </td> - </tr> - <tr> - <td> - `"hello ${ { a = "world" }.a }"` - - `"1 2 ${3}"` - - `"${pkgs.bash}/bin/sh"` - </td> - <td> - String interpolation (expands to `"hello world"`, `"1 2 3"`, `"/nix/store/<hash>-bash-<version>/bin/sh"`) - </td> - </tr> - <tr> - <td> - `true`, `false` - </td> - <td> - Booleans - </td> - </tr> - <tr> - <td> - `null` - </td> - <td> - Null value - </td> - </tr> - <tr> - <td> - `123` - </td> - <td> - An integer - </td> - </tr> - <tr> - <td> - `3.141` - </td> - <td> - A floating point number - </td> - </tr> - <tr> - <td> - `/etc` - </td> - <td> - An absolute path - </td> - </tr> - <tr> - <td> - `./foo.png` - </td> - <td> - A path relative to the file containing this Nix expression - </td> - </tr> - <tr> - <td> - `~/.config` - </td> - <td> - A home path. Evaluates to the `"<user's home directory>/.config"`. - </td> - </tr> - <tr> - <td> - <nixpkgs> - </td> - <td> - Search path. Value determined by [`$NIX_PATH` environment variable](../command-ref/env-common.md#env-NIX_PATH). - </td> - </tr> - <tr> - <td> - *Compound values* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `{ x = 1; y = 2; }` - </td> - <td> - A set with attributes named `x` and `y` - </td> - </tr> - <tr> - <td> - `{ foo.bar = 1; }` - </td> - <td> - A nested set, equivalent to `{ foo = { bar = 1; }; }` - </td> - </tr> - <tr> - <td> - `rec { x = "foo"; y = x + "bar"; }` - </td> - <td> - A recursive set, equivalent to `{ x = "foo"; y = "foobar"; }` - </td> - </tr> - <tr> - <td> - `[ "foo" "bar" "baz" ]` - - `[ 1 2 3 ]` - - `[ (f 1) { a = 1; b = 2; } [ "c" ] ]` - </td> - <td> - Lists with three elements. - </td> - </tr> - <tr> - <td> - *Operators* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `"foo" + "bar"` - </td> - <td> - String concatenation - </td> - </tr> - <tr> - <td> - `1 + 2` - </td> - <td> - Integer addition - </td> - </tr> - <tr> - <td> - `"foo" == "f" + "oo"` - </td> - <td> - Equality test (evaluates to `true`) - </td> - </tr> - <tr> - <td> - `"foo" != "bar"` - </td> - <td> - Inequality test (evaluates to `true`) - </td> - </tr> - <tr> - <td> - `!true` - </td> - <td> - Boolean negation - </td> - </tr> - <tr> - <td> - `{ x = 1; y = 2; }.x` - </td> - <td> - Attribute selection (evaluates to `1`) - </td> - </tr> - <tr> - <td> - `{ x = 1; y = 2; }.z or 3` - </td> - <td> - Attribute selection with default (evaluates to `3`) - </td> - </tr> - <tr> - <td> - `{ x = 1; y = 2; } // { z = 3; }` - </td> - <td> - Merge two sets (attributes in the right-hand set taking precedence) - </td> - </tr> - <tr> - <td> - *Control structures* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `if 1 + 1 == 2 then "yes!" else "no!"` - </td> - <td> - Conditional expression - </td> - </tr> - <tr> - <td> - `assert 1 + 1 == 2; "yes!"` - </td> - <td> - Assertion check (evaluates to `"yes!"`). - </td> - </tr> - <tr> - <td> - `let x = "foo"; y = "bar"; in x + y` - </td> - <td> - Variable definition - </td> - </tr> - <tr> - <td> - `with pkgs.lib; head [ 1 2 3 ]` - </td> - <td> - Add all attributes from the given set to the scope (evaluates to `1`) - </td> - </tr> - <tr> - <td> - *Functions (lambdas)* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `x: x + 1` - </td> - <td> - A function that expects an integer and returns it increased by 1 - </td> - </tr> - <tr> - <td> - `x: y: x + y` - </td> - <td> - Curried function, equivalent to `x: (y: x + y)`. Can be used like a function that takes two arguments and returns their sum. - </td> - </tr> - <tr> - <td> - `(x: x + 1) 100` - </td> - <td> - A function call (evaluates to 101) - </td> - </tr> - <tr> - <td> - `let inc = x: x + 1; in inc (inc (inc 100))` - </td> - <td> - A function bound to a variable and subsequently called by name (evaluates to 103) - </td> - </tr> - <tr> - <td> - `{ x, y }: x + y` - </td> - <td> - A function that expects a set with required attributes `x` and `y` and concatenates them - </td> - </tr> - <tr> - <td> - `{ x, y ? "bar" }: x + y` - </td> - <td> - A function that expects a set with required attribute `x` and optional `y`, using `"bar"` as default value for `y` - </td> - </tr> - <tr> - <td> - `{ x, y, ... }: x + y` - </td> - <td> - A function that expects a set with required attributes `x` and `y` and ignores any other attributes - </td> - </tr> - <tr> - <td> - `{ x, y } @ args: x + y` - - `args @ { x, y }: x + y` - </td> - <td> - A function that expects a set with required attributes `x` and `y`, and binds the whole set to `args` - </td> - </tr> - <tr> - <td> - *Built-in functions* - </td> - <td> - - </td> - </tr> - <tr> - <td> - `import ./foo.nix` - </td> - <td> - Load and return Nix expression in given file - </td> - </tr> - <tr> - <td> - `map (x: x + x) [ 1 2 3 ]` - </td> - <td> - Apply a function to every element of a list (evaluates to `[ 2 4 6 ]`) - </td> - </tr> + <tr> + <th> + Example + </th> + <th> + Description + </th> + </tr> + <tr> + <td> + + + *Basic values* + + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `"hello world"` + + </td> + <td> + + A string + + </td> + </tr> + <tr> + <td> + + ``` + '' + multi + line + string + '' + ``` + + </td> + <td> + + A multi-line string. Strips common prefixed whitespace. Evaluates to `"multi\n line\n string"`. + + </td> + </tr> + <tr> + <td> + + `"hello ${ { a = "world" }.a }"` + + `"1 2 ${3}"` + + `"${pkgs.bash}/bin/sh"` + + </td> + <td> + + String interpolation (expands to `"hello world"`, `"1 2 3"`, `"/nix/store/<hash>-bash-<version>/bin/sh"`) + + </td> + </tr> + <tr> + <td> + + `true`, `false` + + </td> + <td> + + Booleans + + </td> + </tr> + <tr> + <td> + + `null` + + </td> + <td> + + Null value + + </td> + </tr> + <tr> + <td> + + `123` + + </td> + <td> + + An integer + + </td> + </tr> + <tr> + <td> + + `3.141` + + </td> + <td> + + A floating point number + + </td> + </tr> + <tr> + <td> + + `/etc` + + </td> + <td> + + An absolute path + + </td> + </tr> + <tr> + <td> + + `./foo.png` + + </td> + <td> + + A path relative to the file containing this Nix expression + + </td> + </tr> + <tr> + <td> + + `~/.config` + + </td> + <td> + + A home path. Evaluates to the `"<user's home directory>/.config"`. + + </td> + </tr> + <tr> + <td> + + <nixpkgs> + + </td> + <td> + + Search path. Value determined by [`$NIX_PATH` environment variable](../command-ref/env-common.md#env-NIX_PATH). + + </td> + </tr> + <tr> + <td> + + *Compound values* + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `{ x = 1; y = 2; }` + + </td> + <td> + + A set with attributes named `x` and `y` + + </td> + </tr> + <tr> + <td> + + `{ foo.bar = 1; }` + + </td> + <td> + + A nested set, equivalent to `{ foo = { bar = 1; }; }` + + </td> + </tr> + <tr> + <td> + + `rec { x = "foo"; y = x + "bar"; }` + + </td> + <td> + + A recursive set, equivalent to `{ x = "foo"; y = "foobar"; }` + + </td> + </tr> + <tr> + <td> + + `[ "foo" "bar" "baz" ]` + + `[ 1 2 3 ]` + + `[ (f 1) { a = 1; b = 2; } [ "c" ] ]` + + </td> + <td> + + Lists with three elements. + + </td> + </tr> + <tr> + <td> + + *Operators* + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `"foo" + "bar"` + + </td> + <td> + + String concatenation + + </td> + </tr> + <tr> + <td> + + `1 + 2` + + </td> + <td> + + Integer addition + + </td> + </tr> + <tr> + <td> + + `"foo" == "f" + "oo"` + + </td> + <td> + + Equality test (evaluates to `true`) + + </td> + </tr> + <tr> + <td> + + `"foo" != "bar"` + + </td> + <td> + + Inequality test (evaluates to `true`) + + </td> + </tr> + <tr> + <td> + + `!true` + + </td> + <td> + + Boolean negation + + </td> + </tr> + <tr> + <td> + + `{ x = 1; y = 2; }.x` + + </td> + <td> + + Attribute selection (evaluates to `1`) + + </td> + </tr> + <tr> + <td> + + `{ x = 1; y = 2; }.z or 3` + + </td> + <td> + + Attribute selection with default (evaluates to `3`) + + </td> + </tr> + <tr> + <td> + + `{ x = 1; y = 2; } // { z = 3; }` + + </td> + <td> + + Merge two sets (attributes in the right-hand set taking precedence) + + </td> + </tr> + <tr> + <td> + + *Control structures* + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `if 1 + 1 == 2 then "yes!" else "no!"` + + </td> + <td> + + Conditional expression + + </td> + </tr> + <tr> + <td> + + `assert 1 + 1 == 2; "yes!"` + + </td> + <td> + + Assertion check (evaluates to `"yes!"`). + + </td> + </tr> + <tr> + <td> + + `let x = "foo"; y = "bar"; in x + y` + + </td> + <td> + + Variable definition + + </td> + </tr> + <tr> + <td> + + `with pkgs.lib; head [ 1 2 3 ]` + + </td> + <td> + + Add all attributes from the given set to the scope (evaluates to `1`) + + </td> + </tr> + <tr> + <td> + + *Functions (lambdas)* + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `x: x + 1` + + </td> + <td> + + A function that expects an integer and returns it increased by 1 + + </td> + </tr> + <tr> + <td> + + `x: y: x + y` + + </td> + <td> + + Curried function, equivalent to `x: (y: x + y)`. Can be used like a function that takes two arguments and returns their sum. + + </td> + </tr> + <tr> + <td> + + `(x: x + 1) 100` + + </td> + <td> + + A function call (evaluates to 101) + + </td> + </tr> + <tr> + <td> + + `let inc = x: x + 1; in inc (inc (inc 100))` + + </td> + <td> + + A function bound to a variable and subsequently called by name (evaluates to 103) + + </td> + </tr> + <tr> + <td> + + `{ x, y }: x + y` + + </td> + <td> + + A function that expects a set with required attributes `x` and `y` and concatenates them + + </td> + </tr> + <tr> + <td> + + `{ x, y ? "bar" }: x + y` + + </td> + <td> + + A function that expects a set with required attribute `x` and optional `y`, using `"bar"` as default value for `y` + + </td> + </tr> + <tr> + <td> + + `{ x, y, ... }: x + y` + + </td> + <td> + + A function that expects a set with required attributes `x` and `y` and ignores any other attributes + + </td> + </tr> + <tr> + <td> + + `{ x, y } @ args: x + y` + + `args @ { x, y }: x + y` + + </td> + <td> + + A function that expects a set with required attributes `x` and `y`, and binds the whole set to `args` + + </td> + </tr> + <tr> + <td> + + *Built-in functions* + + </td> + <td> + + + + </td> + </tr> + <tr> + <td> + + `import ./foo.nix` + + </td> + <td> + + Load and return Nix expression in given file + + </td> + </tr> + <tr> + <td> + + `map (x: x + x) [ 1 2 3 ]` + + </td> + <td> + + Apply a function to every element of a list (evaluates to `[ 2 4 6 ]`) + + </td> + </tr> </table> |