Brainfuck converter

Yes, it exists. Brainfuck is programming language made of only the following chars: +, -, <, >, [, ].
But you can do every function you need, see: http://en.wikipedia.org/wiki/Brainfuck 
This is the source:


REBOL [
    Title:   "Brainfuck"
    Author: "John Niclasen"
    Date:   21-Mar-2009
    File:   %bf.r
    Purpose: {
        REBOL implementation of this language: http://en.wikipedia.org/wiki/Brainfuck
        bf is 232 bytes compressed (see end of script).
    }
]
bf: func [s] [
    p: make string! 3e4
    insert/dup p #{00} 3e4
    while [not tail? s] [
        switch s/1 [
            #">"     [p: next p s: next s]
            #"<"     [p: back p s: next s]
            #"+"     [p/1: either p/1 = 255 [#{00}][p/1 + 1] s: next s]
            #"-"     [p/1: either p/1 = 0 [#{ff}][p/1 - 1] s: next s]
            #"."     [prin p/1 s: next s]
            #","     [change p input s: next s]
            #"["     [
                if p/1 = 0 [
                    c: 1
                    until [
                        switch first s: next s [
                            #"["     [c: c + 1]
                            #"]"     [c: c - 1]
                        ]
                        c = 0
                    ]
                ]
                s: next s
            ]
            #"]"     [
                c: 1
                until [
                    switch first s: back s [
                        #"]"     [c: c + 1]
                        #"["     [c: c - 1]
                    ]
                    c = 0
                ]
            ]
        ]
    ]
]

or the same script compressed:

Rebol []
bf: do decompress #{
789C7590DD6E83300C855FC50B97FD01D6F506F5E741AC5CB02C2956698A8851
2B4D7BF739199BA0EA72E5F8F83B398E1BBCC1A0B1ABE0529F2D04EEC99F5E60
63DF807CB03DE71F43071D649F45F195DAB7865A8BFECAC035B547103ADC884D
03212F31530715DDBCBDB36061AC82CED42E09EFB5393F080B11F2B2024BDCD8
1EA4863DBC6EB7981ED5518405947ACAAC9E318510CE8DC4EA81580B21CBA5D1
697FA9D034B53F594945BE1B78A6A242727FF6A6821206CFD4FEEEECA80F1302
1321632625CE941E6F318D36D144CF52FDE8FF99A6CF8AA67A668A4F4CE57C03
F00D8B8FCD010000
}


And this is what you can do with the bf function:

bf {++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.}

Hello World!