# polysplit.py

input_ = raw_input("Please enter the vertex coords in the format \"x,y\".\n")
coords = []
while input_:
    for xy in input_.split():
        coords.append(map(lambda x: int(x), xy.split(',')))
    input_ = raw_input()

# Calculate which vertexes to link
splits = []
for i in range(2,len(coords)):
    splitindex = 2;
    while 1:
        if i % splitindex:
            break
        splits.append((i - splitindex, i)) 
        splitindex *= 2;

print "Splits:"
for line in splits:
    print "%d,%d -> %d,%d" % tuple(coords[line[0]] + coords[line[1]])

 # poly.py

 def spdp(p1, p2, p3):
     """ return signum of perp dot product of edges p1..p2 and p2..p3 """
     x1, y1 = p1
     x2, y2 = p2
     x3, y3 = p3
     pdp = (y1 - y2)*(x3 - x2) + (x2 - x1)*(y3 - y2)
     if pdp < 0:
         return -1
     if pdp > 0:
         return 1
     return 0
 
 def isstrictlyconvex(pgon):
     N = len(pgon)
     if N < 3:
         return False
     signum1 = spdp(pgon[0], pgon[1], pgon[2])
     if signum1 == 0:
         return False
     if N == 3:
         return True
     for i in range(1, N):
         signum = spdp(pgon[i], pgon[(i + 1) % N], pgon[(i + 2) % N])
         if signum != signum1:
             return False
     return True
 
 input_ = raw_input('Enter vertices: ').split()
 pgon = []
 try:
     for pair in input_:
         x, y = pair.split(',')
         pgon.append((int(x), int(y)))
 except ValueError:
     print "No, no, no. You're supposed to enter the vertices as comma'ed pairs of integers."
     print "The pairs should be separated by whitespace. Example: -1,0 0,2 1,0 0,-2"
 else:
     if not isstrictlyconvex(pgon):
         print "What you supplied is not a (strictly) convex polygon."
         print "Maybe Faxmachinen has a better solution for you?"
     elif len(pgon) < 5:
         print "That's optimal as it is."
     else:
         x0, y0 = pgon[0]
         for i, (x, y) in enumerate(pgon[3:-1:2]):
             print '%d. Draw a line from %d,%d to %d,%d.' % (i + 1, x0, y0, x, y)
         print "That's it, well done!" 

You're lucky: in this challenge, you have the chance to dream up your very own programming language. But, before you go overboard to create the language that makes Python look ugly, you also have to write a program that can 1) translate programs in your new language into brainfuck, and 2) translate brainfuck programs into your new language.

For example, I've just invented BabyTalk. It is as trivially isomorphic (well, nearly) with brainfuck as Ook! is. Here's an example:

Ma! Ma? Ma. Ma. Ma. Ma! Ma? Ma? Ma? Ma? Ma ma ma ma ma. Ma ma ma ma. Ma? Ma. Ma. Ma. Ma! Ma? Ma! Ma ma ma ma. Ma. Ma! Ma? Ma! Ma? Ma! Ma! Ma? Ma! Ma? Ma ma ma ma? Ma. Ma. Ma! Ma ma ma ma. Ma! Ma ma ma? Ma ma ma! Ma ma ma! Ma ma ma? Ma ma! Ma ma ma ma ma ma! Ma ma ma ma. Ma? Ma! Ma ma ma ma ma ma ma ma! Ma ma ma ma? Ma! Ma ma ma ma ma ma ma ma. Ma? Ma? Ma! Ma? Ma! Ma? Ma. Ma ma ma ma ma ma ma ma! Ma ma ma ma ma ma ma ma? Ma. Ma! Ma? Ma ma ma ma ma ma ma ma. Ma ma ma ma? Ma. Ma! Ma ma ma ma ma ma ma ma? Ma ma ma! Ma ma ma. Ma. Ma! Ma? Ma? Ma? Ma! Ma. Ma! Ma! Ma. Ma! Ma? Ma. Ma. Ma! Ma ma ma ma ma ma ma ma! Ma ma ma ma. Ma ma ma ma ma ma ma ma! Ma! Ma? Ma. Ma ma ma ma ma ma ma ma! Ma ma? Ma ma? Ma ma! Ma ma? Ma ma? Ma ma? Ma ma ma ma ma ma ma ma. Ma ma. Ma ma. Ma ma! Ma ma! Ma ma! Ma ma! Ma ma? Ma ma? Ma ma ma ma ma ma ma ma! Ma ma ma ma? Ma. Ma ma ma ma ma ma ma ma? Ma ma ma ma? Ma ma ma ma ma ma ma ma.

(The above prints 'Hello World!', a reasonable thing for a baby to say. Full stops, exclamation marks and question marks are interchangeable, to give the programmer that extra bit of poetic freedom.)

The deadline is 24 hours from this post.

Evil pyramid schemes included:

# pdcompiler.py

# MUAHAHA!
def opValue(script):
    if script and script[0] == "two":
        script.pop(0)
        if script and script[0] == "three":
            script.pop(0)
            if script and script[0] == "four":
                script.pop(0)
                return 8
            return 4
        return 2
    return 1

def popTo(token, script):
    while script.pop(0) != token:
        if not script:
            print 'Error: Expected "%s", found EOF instead.' % token
            return False
    return True


# Open files and read
fname = raw_input("Please enter the Puppet Dance file to compile.\n")
infile = open(fname, 'r')
outfile = open(fname + '.b', 'w')
script = infile.read().lower().split()
infile.close()

# Compile
output = []
token_num = 0
error = False
while script:
    token = script.pop(0)
    token_num += 1

    # Wishing Python had switch() right about now
    if token == "\o":
        if not popTo("o/", script):
            error = True
            break
    elif token == "o/":
        print 'Warning: Unexpected "o/" at token %d.' % token_num
    elif token == "one":
        opValue(script)  # Do nothing
    elif token == "up":
        output.append("+" * opValue(script))
    elif token == "down":
        output.append("-" * opValue(script))
    elif token == "left":
        output.append("<" * opValue(script))
    elif token == "right":
        output.append(">" * opValue(script))
    elif token == "go":
        output.append("[")
    elif token == "repeat":
        output.append("]")
    elif token == "jump":
        output.append(",>" * opValue(script))
    elif token == "spin":
        output.append(".>" * opValue(script))
    elif token == "two" or token == "three" or token == "four":
        print 'Error: Did not expect "%s" at %d.' % (token, token_num)
        error = True
        break
    else:
        print 'Error: Unknown token "%s" at %d.' % (token, token_num)
        error = True
        break

if not error:
    # Optimize a little
    outstr = "".join(output).replace("><", "").replace("<>", "")

    # Write to output file
    outfile.write(outstr)
    print 'Compiled successfully to "%s.b"' % fname

----------------------------

# pddecomp.py

def repeat_count(element, array, index):
    result = 0
    while index < len(array) and array[index] == element:
        result += 1
        index += 1
    return result

# Okay beating a dead horse here
def multiop(num, op):
    result = []
    while num > 0:
        result.append(op)
        if num > 1:
            result.append("two")
            if num > 3:
                result.append("three")
                if num > 7:
                    result.append("four")
                    num -= 8
                else:
                    num -= 4
            else:
                num -= 2
        else:
            num -= 1
    return result

# Open files and read
fname = raw_input("Please enter the brainfuck file to decompile.\n")
infile = open(fname, 'r')
outfile = open(fname + '.pd', 'w')
data = infile.read()
infile.close()

output = []
i = 0
while i < len(data):
    ch = data[i]
    rc = repeat_count(ch, data, i)
    if ch == '>':
        output += multiop(rc, "right")
        i += rc
    elif ch == '<':
        output += multiop(rc, "left")
        i += rc
    elif ch == '+':
        output += multiop(rc, "up")
        i += rc
    elif ch == '-':
        output += multiop(rc, "down")
        i += rc
    elif ch == ',':
        output += multiop(rc, "jump")
        i += rc
    elif ch == '.':
        output += multiop(rc, "spin")
        i += rc
    elif ch == '[':
        output.append("go")
        i += 1
    elif ch == ']':
        output.append("repeat")
        i += 1
outfile.write(" ".join(output))
outfile.close()
print "Done."

----------------------------

\o	hello.pd
	Hello World in Puppet Dance	o/

Right one two three  \o Note the cosmetic no-op o/
Up two three four
Go
	Down left up two three four up
	Right one two repeat
Right two three
Up two three four up two
Go
	Down left one two
	Up two three four up two left
	Up two three four up two left
	Up two three four up two left
	Up two three four up two left
	Right two three right repeat

Right one two three
Up two three
Go
	Down left up two three four
	Right one two repeat
Right one two three
Up two three up
Go
	Down left
	Up two three four
	Up two three four
	Up one two
	Right one two repeat
Right two three
Up two three four up two
Go
	Down left one two
	Up two three four up two left
	Up two three four up two left
	Up two three four up two left
	Up two three four up two left
	Right two three right repeat

Left one two three
Left up two three four
Left up two three four up two three up two
Left up two three four up two up
Left up two left
Left up two three four up two up
Left up two three four
Left up two three four
Left up left one two

Go
	Spin one two three repeat

Behold the horror of switch: the language with nothing but switch-case statements...

to_switch.c

#include 
#include 
#include 

void parse_bf( int, int, int, char* );
void indent( const char * );
void indent_output( int );

void fwd( int* );
void rwd( int* );

char code[2000];
char output[1000];

int id = 0;

int main( int argc, char **argv )
{
	FILE * f;
	int c;

	int numi = 0;
	int numo = 0;

	int i = 0;
	char data[1000] = {0};
	
	if( argc != 2 )
	{
		printf("Usage: %s filename\n", argv[0] );
		exit(0);
	}

	f = fopen( argv[1], "r" );
	while( !feof(f) )
	{
		c = getc( f );
		code[i] = c;
		if( c == '.' ) numo++;
		i++;
	}
	fclose(f);
	code[i] = 0;

	if( numo == 0 )
	{
		exit(0);	// if there's no output, no need for any code
	}

	parse_bf( 0, 0, 0, data );
}

void parse_bf( int ip, int dp, int op, char *data )
{
	char *newdata = malloc( 1000 );
	char c;
	char s[20];
	memcpy( newdata, data, 1000 );	// new copy of the data space

	for(;code[ip];ip++)				// continue until end of code
	{
		switch(code[ip])			// normal brain fuck operators
		{
			case '+' :
				newdata[dp]++;
				break;
			case '-' :
				newdata[dp]--;
				break;
			case '>' :
				dp = (dp+1) % 1000;
				break;
			case '<' :
				dp--;
				if( dp<0 ) dp+=1000;
				break;
			case '[' :
				if( newdata[dp] == 0 )
					fwd(&ip);			// branch foward
				break;
			case ']' :
				if( newdata[dp] != 0 )
					rwd(&ip);			// branch backward
				break;
			case '.' :
				output[op] = newdata[dp];	// add to output buffer
				op++;
				break;
			case ',' :
				indent("switch {");		// possible change in execution here
				id++;
				// limited to kb chars
				for(c=0x20;c<0x7F;c++)	// try all input chars
				{
					sprintf(s,"case %d",c);
					indent(s);
					newdata[dp] = c;
					id++;
					parse_bf( ip+1, dp, op, newdata );
					indent("break");
					id--;
				}
				id--;
				indent("}");
				free(newdata);
				return;
		}
	}
	indent_output(op);	// print output
	free(newdata);		// clean up
}

void indent( const char *s )	// pretty up output
{
	int i;
	for(i=0;i<id;i++)
		printf("\t");
	printf("%s\n",s );
}

void indent_output( int lim )
{
	int i,j;
	for(i=0;i<lim;i++)
	{
		for(j=0;j<id;j++)
			printf("\t");
		printf("putc");
		printf(" %d\n", output[i] );
	}
}

void fwd( int *p )
{
	int cnt;
	int q;

	for(q=*p+1,cnt=1; cnt > 0; q++ )
	{
		if( code[q] == ']' )
			cnt--;
		if( code[q] == '[' )
			cnt++;
	}
	*p = q;
}

void rwd( int *p )
{
	int cnt;
	int q;

	for(q=*p-1,cnt=1; cnt > 0; q-- )
	{
		if( code[q] == '[' )
			cnt--;
		if( code[q] == ']' )
			cnt++;
	}
	*p = q;
}

from_switch.pl

open( FILE, " )
{
	$line = $_;

	if( $line =~ /putc (\d+)/ )
	{
		$char = $1;
		print ">";							# get a clean cell
		for($i=0;$i<$char;$i++)
		{
			print "+";						# generate the character
		}
		print ".[-]<\n";					# output and clear cell
	}
	elsif( $line =~ /switch/ )
	{
		print ",>\n";						# read in char
	}
	elsif( $line =~ /case (\d+)/ )
	{
		$num = $1;
		print "<[->+>+<<]>>[-<<+>>]<\n";	# copy input to next cell
		for($i=0;$i<$num;$i++)
		{
			print "-";						# will be zero if eqal
		}
		print "\n>+<[>-<[-]]>[-\n"			# branch if not equal
	}
	elsif( $line =~ /break/ )
	{
		print "]<\n";						# end branch
	}
}

Switch behaves as follows:
switch-case-break works similar to C, but switch uses the next char from stdin as its condition. putc outputs the following number as a char

For example, Hello World is implemented via this switch code: putc 72 putc 101 putc 108 putc 108 putc 111 putc 32 putc 87 putc 111 putc 114 putc 108 putc 100 putc 33 putc 10 (Just in case I missed an < to escape, the source files are also: http://omega0.xepher.net/stuff/to_switch.c http://omega0.xepher.net/stuff/from_switch.pl )

Thank you both for your submissions.

Faxmachinen: Puppet Dance has much to recommend it - the cosmetic no-op, the comment markers and the pyramid scheme. I also like how easy it is to re-use code, e.g. to entertain a children's birthday party.

omega0: now that's purely evil. I especially like how you emulate a brainfuck program in order to compile it. Your turn.

And so it continues...