# Generators

Generators are functions that create file formats from nix data structures, e. g. for configuration files. There are generators available for: `INI`, `JSON` and `YAML`

All generators follow a similar call interface: `generatorName configFunctions data`, where `configFunctions` is an attrset of user-defined functions that format nested parts of the content. They each have common defaults, so often they do not need to be set manually. An example is `mkSectionName ? (name: libStr.escape [ "[" "]" ] name)` from the `INI` generator. It receives the name of a section and sanitizes it. The default `mkSectionName` escapes `[` and `]` with a backslash.

Generators can be fine-tuned to produce exactly the file format required by your application/service. One example is an INI-file format which uses `:` as separator, the strings `"yes"`/`"no"` as boolean values and requires all string values to be quoted:

    with lib;
    let
      customToINI = generators.toINI {
        # specifies how to format a key/value pair
        mkKeyValue = generators.mkKeyValueDefault {
          # specifies the generated string for a subset of nix values
          mkValueString = v:
                 if v == true then ''"yes"''
            else if v == false then ''"no"''
            else if isString v then ''"${v}"''
            # and delegats all other values to the default generator
            else generators.mkValueStringDefault {} v;
        } ":";
      };

    # the INI file can now be given as plain old nix values
    in customToINI {
      main = {
        pushinfo = true;
        autopush = false;
        host = "localhost";
        port = 42;
      };
      mergetool = {
        merge = "diff3";
      };
    }

This will produce the following INI file as nix string:

    [main]
    autopush:"no"
    host:"localhost"
    port:42
    pushinfo:"yes"
    str\:ange:"very::strange"

    [mergetool]
    merge:"diff3"

Nix store paths can be converted to strings by enclosing a derivation attribute like so: `"${drv}"`.

Detailed documentation for each generator can be found in `lib/generators.nix`.