Brainfuck minifier

Input

+++++ +++++        initialize counter (cell #0) to 10
[ use loop to set the next four cells to 70/100/30/10
    > +++++ ++                      add  7 to cell #1
    > +++++ +++++                   add 10 to cell #2
    > +++                           add  3 to cell #3
    > +                             add  1 to cell #4
    <<<< -                decrement counter (cell #0)
]
> ++ .                                      print 'H'
> + .                                       print 'e'
+++++ ++ .                                  print 'l'
.                                           print 'l'
+++ .                                       print 'o'
> ++ .                                      print ' '
<< +++++ +++++ +++++ .                      print 'W'
> .                                         print 'o'
+++ .                                       print 'r'
----- - .                                   print 'l'
----- --- .                                 print 'd'
> + .                                       print '!'
> .                                         print '\n'

Minified result (permalink)

lol

Before: 1,082 bytes
After: 111 bytes
Compression ratio: 89.74%

About brainfuck

Brainfuck (not capitalized except at the start of a sentence) is an esoteric programming language. It has eight commands — +-<>[],. — and ignores all other characters. As a result, no special syntax for comments is needed, as long as the comments don’t contain the command characters.