my %map =
  ( 'a' => '4'
  , 'e' => '3'
  , 'h' => '|-|'
  , 'i' => '1'
  , 'l' => '1'
  , 'o' => '0'
  , 's' => '5'
  , 't' => '7'
  ) ;

#  $reverse is set by some other means
@map{ values %map } = keys %map if $reverse ;

while ( <DATA> )
{ foreach my $k ( keys %map )
  { s/ $k / $map{$k} /giex;
  }
  print;
}