GroupBy list method

The groupBy (or group_by) method is used to group the items in a list to a list of groups.

The method takes a single argument that is the function of the condition. The format is <list>.groupBy($<name> <action_with_$name>).

The returned list of items will be a class with :key as the result of the action and :values as the list of items that answer that value.

For example:

findit  -w 'IS DIR' -d 'name: `name` - `files.groupBy($file $file.extension).map($group {:extension $group::key, :count $group::values.length()})`'

will list the directory with the number of files per extensions.