Concatenate arrays that are parameters of resources in puppet without the use of ruby code

foo.pp

class foo ($concatenate = []) { 
  class simple_resource {
    exec { 'env':
      command => 'env | sort',
      path => '/usr/bin',
      environment => ['FOO=bar'],
      logoutput => true,
    }
  }

  class complex_resource($extraenv) inherits simple_resource {
    Exec['env'] {
      environment +> $extraenv,
    }
  }

  if $concatenate {
    class { 'complex_resource': extraenv => $concatenate }
  } else {
    include simple_resource
  }
}

class { 'foo': concatenate => ['FOO2=bar', 'FOO3=sadad'] }