Converting Puppet Erb Template to Epp

As Dominic Cleal mentions in the comment, select() is not a Puppet function, however filter() is and is the equivalent of select in Ruby.

Therefore:

Given a class:

class foo () {

  # Some test data.
  $filter = {
    'filtertype' => 'foo',
    'apples'     => 1,
    'bananas'    => 2,
  }

  # How to declare the ERB template for comparison:
  file { '/foo':
    ensure  => file,
    content => template('foo/mytemplate.erb'),
  }

  # How to declare the EPP template for comparison:
  file { '/bar':
    ensure  => file,
    content => epp('foo/mytemplate.epp', {'filter' => $filter}),
  }
}

Content of the ERB file exactly as given in the question:

<% @filter.select{|x| x != 'filtertype'}.sort.each do |key, element| -%>
<%= key %>: '<%= element %>'
<% end -%>

Content of an equivalent EPP file:

<% | Hash $filter | -%>
<% include stdlib -%>
<% $filter.keys.sort.filter |$k| {$k != 'filtertype'}.each |$k| { -%>
<%= $k %>: '<%= $filter[$k] %>'
<% } -%>

Things to note:

1) You need include stdlib to access the keys and sort functions.

2) The variable name $filter now clashes with the built-in Puppet function filter(), which is syntactically fine, but confusing, so you would consider renaming the $filter variable to something else for clarity.

Also, if you don't care about sorting the keys, then I could make what you tried work using:

<% | Hash $filter | -%>
<% $filter.filter |$k| {$k[0] != 'filtertype'}.each |$k, $v| { -%>
<%= $k %>: '<%= $v %>'
<% } -%>

See also here where I just answered a similar question.