pkgs-lib: Implement settings format for Elixir

This commit is contained in:
Minijackson 2021-04-10 16:04:35 +02:00 committed by Yt
parent ea84cd6895
commit 6a96ddb675
3 changed files with 356 additions and 0 deletions

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@ -66,6 +66,45 @@ have a predefined type and string generator already declared under
and returning a set with TOML-specific attributes `type` and
`generate` as specified [below](#pkgs-formats-result).
`pkgs.formats.elixirConf { elixir ? pkgs.elixir }`
: A function taking an attribute set with values
`elixir`
: The Elixir package which will be used to format the generated output
It returns a set with Elixir-Config-specific attributes `type`, `lib`, and
`generate` as specified [below](#pkgs-formats-result).
The `lib` attribute contains functions to be used in settings, for
generating special Elixir values:
`mkRaw elixirCode`
: Outputs the given string as raw Elixir code
`mkGetEnv { envVariable, fallback ? null }`
: Makes the configuration fetch an environment variable at runtime
`mkAtom atom`
: Outputs the given string as an Elixir atom, instead of the default
Elixir binary string. Note: lowercase atoms still needs to be prefixed
with `:`
`mkTuple array`
: Outputs the given array as an Elixir tuple, instead of the default
Elixir list
`mkMap attrset`
: Outputs the given attribute set as an Elixir map, instead of the
default Elixir keyword list
::: {#pkgs-formats-result}
These functions all return an attribute set with these values:
:::
@ -74,6 +113,12 @@ These functions all return an attribute set with these values:
: A module system type representing a value of the format
`lib`
: Utility functions for convenience, or special interactions with the format.
This attribute is optional. It may contain inside a `types` attribute
containing types specific to this format.
`generate` *`filename jsonValue`*
: A function that can render a value of the format to a file. Returns

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@ -137,6 +137,97 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>pkgs.formats.elixirConf { elixir ? pkgs.elixir }</literal>
</term>
<listitem>
<para>
A function taking an attribute set with values
</para>
<variablelist>
<varlistentry>
<term>
<literal>elixir</literal>
</term>
<listitem>
<para>
The Elixir package which will be used to format the
generated output
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
It returns a set with Elixir-Config-specific attributes
<literal>type</literal>, <literal>lib</literal>, and
<literal>generate</literal> as specified
<link linkend="pkgs-formats-result">below</link>.
</para>
<para>
The <literal>lib</literal> attribute contains functions to
be used in settings, for generating special Elixir values:
</para>
<variablelist>
<varlistentry>
<term>
<literal>mkRaw elixirCode</literal>
</term>
<listitem>
<para>
Outputs the given string as raw Elixir code
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>mkGetEnv { envVariable, fallback ? null }</literal>
</term>
<listitem>
<para>
Makes the configuration fetch an environment variable
at runtime
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>mkAtom atom</literal>
</term>
<listitem>
<para>
Outputs the given string as an Elixir atom, instead of
the default Elixir binary string. Note: lowercase
atoms still needs to be prefixed with
<literal>:</literal>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>mkTuple array</literal>
</term>
<listitem>
<para>
Outputs the given array as an Elixir tuple, instead of
the default Elixir list
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>mkMap attrset</literal>
</term>
<listitem>
<para>
Outputs the given attribute set as an Elixir map,
instead of the default Elixir keyword list
</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
</variablelist>
<para xml:id="pkgs-formats-result">
These functions all return an attribute set with these values:
@ -152,6 +243,19 @@
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>lib</literal>
</term>
<listitem>
<para>
Utility functions for convenience, or special interactions
with the format. This attribute is optional. It may contain
inside a <literal>types</literal> attribute containing types
specific to this format.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>generate</literal>

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@ -14,6 +14,15 @@ rec {
# The description needs to be overwritten for recursive types
type = ...;
# Utility functions for convenience, or special interactions with the
# format (optional)
lib = {
exampleFunction = ...
# Types specific to the format (optional)
types = { ... };
...
};
# generate :: Name -> Value -> Path
# A function for generating a file with a value of such a type
generate = ...;
@ -147,4 +156,202 @@ rec {
'';
};
/* For configurations of Elixir project, like config.exs or runtime.exs
Most Elixir project are configured using the [Config] Elixir DSL
Since Elixir has more types than Nix, we need a way to map Nix types to
more than 1 Elixir type. To that end, this format provides its own library,
and its own set of types.
To be more detailed, a Nix attribute set could correspond in Elixir to a
[Keyword list] (the more common type), or it could correspond to a [Map].
A Nix string could correspond in Elixir to a [String] (also called
"binary"), an [Atom], or a list of chars (usually discouraged).
A Nix array could correspond in Elixir to a [List] or a [Tuple].
Some more types exists, like records, regexes, but since they are less used,
we can leave the `mkRaw` function as an escape hatch.
For more information on how to use this format in modules, please refer to
the Elixir section of the Nixos documentation.
TODO: special Elixir values doesn't show up nicely in the documentation
[Config]: <https://hexdocs.pm/elixir/Config.html>
[Keyword list]: <https://hexdocs.pm/elixir/Keyword.html>
[Map]: <https://hexdocs.pm/elixir/Map.html>
[String]: <https://hexdocs.pm/elixir/String.html>
[Atom]: <https://hexdocs.pm/elixir/Atom.html>
[List]: <https://hexdocs.pm/elixir/List.html>
[Tuple]: <https://hexdocs.pm/elixir/Tuple.html>
*/
elixirConf = { elixir ? pkgs.elixir }:
with lib; let
toElixir = value: with builtins;
if value == null then "nil" else
if value == true then "true" else
if value == false then "false" else
if isInt value || isFloat value then toString value else
if isString value then string value else
if isAttrs value then attrs value else
if isList value then list value else
abort "formats.elixirConf: should never happen (value = ${value})";
escapeElixir = escape [ "\\" "#" "\"" ];
string = value: "\"${escapeElixir value}\"";
attrs = set:
if set ? _elixirType then specialType set
else
let
toKeyword = name: value: "${name}: ${toElixir value}";
keywordList = concatStringsSep ", " (mapAttrsToList toKeyword set);
in
"[" + keywordList + "]";
listContent = values: concatStringsSep ", " (map toElixir values);
list = values: "[" + (listContent values) + "]";
specialType = { value, _elixirType }:
if _elixirType == "raw" then value else
if _elixirType == "atom" then value else
if _elixirType == "map" then elixirMap value else
if _elixirType == "tuple" then tuple value else
abort "formats.elixirConf: should never happen (_elixirType = ${_elixirType})";
elixirMap = set:
let
toEntry = name: value: "${toElixir name} => ${toElixir value}";
entries = concatStringsSep ", " (mapAttrsToList toEntry set);
in
"%{${entries}}";
tuple = values: "{${listContent values}}";
toConf = values:
let
keyConfig = rootKey: key: value:
"config ${rootKey}, ${key}, ${toElixir value}";
keyConfigs = rootKey: values: mapAttrsToList (keyConfig rootKey) values;
rootConfigs = flatten (mapAttrsToList keyConfigs values);
in
''
import Config
${concatStringsSep "\n" rootConfigs}
'';
in
{
type = with lib.types; let
valueType = nullOr
(oneOf [
bool
int
float
str
(attrsOf valueType)
(listOf valueType)
]) // {
description = "Elixir value";
};
in
attrsOf (attrsOf (valueType));
lib =
let
mkRaw = value: {
inherit value;
_elixirType = "raw";
};
in
{
inherit mkRaw;
/* Fetch an environment variable at runtime, with optional fallback
*/
mkGetEnv = { envVariable, fallback ? null }:
mkRaw "System.get_env(${toElixir envVariable}, ${toElixir fallback})";
/* Make an Elixir atom.
Note: lowercase atoms still need to be prefixed by ':'
*/
mkAtom = value: {
inherit value;
_elixirType = "atom";
};
/* Make an Elixir tuple out of a list.
*/
mkTuple = value: {
inherit value;
_elixirType = "tuple";
};
/* Make an Elixir map out of an attribute set.
*/
mkMap = value: {
inherit value;
_elixirType = "map";
};
/* Contains Elixir types. Every type it exports can also be replaced
by raw Elixir code (i.e. every type is `either type rawElixir`).
It also reexports standard types, wrapping them so that they can
also be raw Elixir.
*/
types = with lib.types; let
isElixirType = type: x: (x._elixirType or "") == type;
rawElixir = mkOptionType {
name = "rawElixir";
description = "raw elixir";
check = isElixirType "raw";
};
elixirOr = other: either other rawElixir;
in
{
inherit rawElixir elixirOr;
atom = elixirOr (mkOptionType {
name = "elixirAtom";
description = "elixir atom";
check = isElixirType "atom";
});
tuple = elixirOr (mkOptionType {
name = "elixirTuple";
description = "elixir tuple";
check = isElixirType "tuple";
});
map = elixirOr (mkOptionType {
name = "elixirMap";
description = "elixir map";
check = isElixirType "map";
});
# Wrap standard types, since anything in the Elixir configuration
# can be raw Elixir
} // lib.mapAttrs (_name: type: elixirOr type) lib.types;
};
generate = name: value: pkgs.runCommandNoCC name
{
value = toConf value;
passAsFile = [ "value" ];
nativeBuildInputs = [ elixir ];
} ''
cp "$valuePath" "$out"
mix format "$out"
'';
};
}