I decided that for today, I’d show the most thoroughly evil programming language ever
devised. This is a language so thoroughly evil that it’s named Malbolge after a circle
of hell. It’s so evil that it’s own designer was not able to write a hello world program! In
fact, the only way that anyone managed to write a “Hello World” was by designing a genetic algorithm
to create one. This monstrosity is so thoroughly twisted that I decided to put it in the “Brain and Behavior” category on ScienceBlogs, because it’s a demonstration of what happens when you take a brain, and twist it until it breaks.

What makes it so thoroughly evil?

1. It’s based on trinary.
2. All programs consist of nothing but a sequence of numbers.
3. Opcodes are not allowed in the source code. All opcodes must
   be encrypted using a very silly encryption scheme.

The Malbolge interpreter has three registers, named “C” (code),
“D” (data), and “A” (accumulator). It’s also got a memory – each address in memory can store a value that is 10 trinary digits wide.

The way that code works is that it loads the value in the memory cell addressed by C. That value is added to the current contents of “C”,
and then it takes the remainder of dividing that sum by 94. The result
is an opcode. Oh, and just for the sake of annoyingness, if the value of
the cell referenced by “C” is not in the range 33-126 (base 10),
then the program terminates with an error.

The opcodes that can be used in a Malbolge program are:

For opcode 62, what you do is take each trinary digit d of the cell referenced by D, and each trinary digit a of the contents of A, and then look
in the following table for the result for that trinary digit.

Once the opcode is complete, if the opcode modified A, then the resulting
value of A is stored into the memory cell referenced by D. If the opcode did not modify
C, then C is incremented by 1. Finally, if the contents of
the cell pointed at by C are in the range 33-126 (the range of ASCII printable characters), then
they’re translated up in the following table, and exchanged for the value of
the ASCII code of the character in the same position in the other row:

5z]&gqtyfr$(we4{WP)H-Zn,[%3dL+Q;>U!pJS72FhOA1C
B6v^=I_0/8|jsb9m<.TVac`uY*MK'X~xDl}REokN:#?G"i@

(In the original version of this post, in the above paragraph, I accidentally omitted the
clause about how/when the value of A is stored to memory; I also originally forgot to mention the wy that C is incremented.)

Now, finally, the first hello world program in Malbolge:

(=<`$9]7<5YXz7wT.3,
+O/o'K%$H"'~D|#z@b=
`{^Lx8%$Xmrkpohm-kN
i;gsedcba`_^][ZYXW
VUTSRQPONMLKJIHGFED
CBA@?>=<;:9876543s+
O<oLm

Don’t ask me to explain how it works. I don’t understand it either.

For an example of a kinda-sorta-realish program in Malbolge, here’s an
implementation of a program that prints the lyrics of the “99 Bottles of Beer” song:

b'`;$9!=IlXFiVwwvtPO0)pon%IHGFDV|dd@Q=+^:('&Y$#m!1S|.QOO=v('98$65aCB}0i.Tw+QPU'7qK#I20jiDVgG
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So. Pointless? Yes. Evil? Absolutely.