# Generators {#sec-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: ```nix 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 ''"${v}"'' # and delegats all other values to the default generator else generators.mkValueStringDefault {} v; } ":"; }; # the INI file can now be given as plain old nix values in customToINI { main = { pushinfo = true; autopush = false; host = "localhost"; port = 42; }; mergetool = { merge = "diff3"; }; } ``` This will produce the following INI file as nix string: ```INI [main] autopush:"no" host:"localhost" port:42 pushinfo:"yes" str\:ange:"very::strange" [mergetool] merge:"diff3" ``` ::: {.note} Nix store paths can be converted to strings by enclosing a derivation attribute like so: `"${drv}"`. ::: Detailed documentation for each generator can be found in `lib/generators.nix`.