BF em 23 linhas (legível)

bf.red

Red []
bf: function [prog][
    size: 30000
    cells: make string! size
    append/dup cells null size
    parse prog [
        some [
              ">" (cells: next cells)
            | "<" (cells: back cells)
            | "+" (cells/1: cells/1 + 1)
            | "-" (cells/1: cells/1 - 1)
            | "." (prin cells/1)
            | "," (cells/1: first input "")
            | "[" [if (cells/1 = null) thru "]" | none]
            | "]" [
               pos: if (cells/1 <> null)
               (pos: find/reverse pos #"[") :pos
               | none
              ]
            | skip
        ]
    ]
]