Talk:*brainfuck
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Two things:
- I am probably not fully comprehending how *brainfuck pointers work, but when you say "start the program with >+ so that cell 0 initially points to cell 1", you're sure you don't you mean "start the program with +>"?
- I am not convinced that this belongs in the "Brainfuck equivalents" category. Most of the languages in that category are equivalent to brainfuck in a very narrow sense -- like, you make a simple transformation of the input, and you end up with a program with the 8 brainfuck commands, and you run that. If anything much more than that is involved, in my opinion, it shouldn't be in that category. BitChanger is a good example (and I think *brainfuck is more different from brainfuck than BitChanger is.) (I might also argue that Pure BF doesn't belong in that category for that reason.) Chris Pressey (talk) 00:14, 28 September 2012 (UTC)
- > and < are just 0 and 1 (I just thought it would not be completely absurd to use the remaining two brainfuck commands as numbers, that "sounded" confusing and esoteric), so >+ is "0+", which means "increment cell 0". A program cannot start with +>, as the first + wouldn't have an argument (though my interpreter sets the argument to 0 by default). It is supposed to be simple, so if you did not understand something please do tell what because it means that I probably need to rewrite the explanation. Imagine if it were a C program:
- 0+ means "ptr++;"
- 1+ means "(*ptr)++;"
- 2+ means "(*(*ptr))++;"
- 3+ means "(*(*(*ptr)))++;"
- and so on (if ptr is cell 0). Thus the translated program starts with 0+ which sets ptr (cell 0) to cell 1; brainfuck >and < translate as 0+ and 0- (increment cell 0), and brainfuck + and - translate as 1+ and 1-" (increment the cell pointed to by cell 0). An instruction should always be preceded by its argument, except that "
n++m-.," for instance is strictly equivalent to "n+n+m-m.m," (with n and m being numbers, which in *brainfuck are written as strings of > and <).
- As for the categories I honestly don't know. I put it there because the translation to brainfuck was so simple (brainfuck uses 1 pointer and an infinity of memory tapes, and *brainfuck can use any memory cell as a pointer, so the translation is basically doing "use cell 0 as the data pointer, and all cells starting with cell 1 as regular memory cells". Strictly speaking it means that *brainfuck is "more powerful" than brainfuck (for instance, a brainfuck derivative with 2 data pointers and 16 instructions, the additional 8 being copies of the first 8 but operating with the second data pointer, would be as easy to translate to *brainfuck than the regular brainfuck was). But I thought that being "more powerful" was technically the same as being "equivalent", because the added possibilities are not really relevant, neither theoretically (because brainfuck is already Turing-complete) nor in practice (because nobody is gonna write programs in *brainfuck anyway). --Koen (talk) 12:22, 28 September 2012 (UTC)
- Oh, OK. Thanks for the elaboration. I was confused about several things, one of which was where the argument is supposed to be, relative to the instruction (reading comprehension fail on my part.) As for the category -- I will probably take the discussion over to Category talk:Brainfuck equivalents. Chris Pressey (talk) 14:15, 28 September 2012 (UTC)