title: Space character in regex is not recognised
body: <p>I'm writing a simple program - please see below for my code with comments. Does anyone know why the space character is not recognised in line 10? When I run the code, it finds the :: but does not replace it with a space.</p>
  
  <pre><code>1  #!/usr/bin/perl
  2
  3  # This program replaces :: with a space
  4  # but ignores a single :
  5
  6  $string = 'this::is::a:string';
  7
  8  print "Current: $string\n";
  9 
  10 $string =~ s/::/\s/g;
  11 print "New: $string\n";
  </code></pre>