joyrexus/demo.txt

## demo.txt
% marko.coffee -x try.python.md > try.py
% python try.py
hello world!
yes!
% marko.coffee -x try.python.md | python -s
hello world!
yes!

## marko.coffee
#!/usr/bin/env coffee

help = '''

  marko [options] FILES

  options:

    -h, --help        show help
    -r, --run         run code blocks
    -x, --extract     extract code blocks

'''

fs = require 'fs'
coffee = require 'coffee-script'
marked = require 'marked'
argv = require('optimist')
  .boolean(['h', 'r', 'x'])
  .alias('h', 'help')
  .alias('r', 'run')
  .alias('x', 'extract')
  .argv

print = console.log
print help if argv.help

head = '''
       <!DOCTYPE html>
       <meta charset="utf-8">
       <link rel="stylesheet" href="style.css">
       <body>

       '''

codeFrom = (source) ->
  (t.text for t in marked.lexer(source) when t.type == 'code').join "\n"

for file in argv._ when file.match /\.(litcoffee|md)/i
  source = fs.readFileSync file, 'utf8'
  if argv.run and /coffee/.test file
      coffee.eval codeFrom source
  else if argv.extract
      print codeFrom source
  else
    print head, marked source

## try.python.md

      
    Raw
  

              try.python.md
            
          
    Demo

Note that Marked's lexer makes it easy to extract code blocks from markdown files:
# codeFrom = (source) ->
#  (t.text for t in marked.lexer(source) when t.type == 'code').join "\n"
Hence, it's not hard to use this to extract and run, say, python code blocks.
print "hello world!"
A bit more.
from collections import defaultdict as dd

def autodict(): return dd(autodict)

d = autodict()
d['an']['arbitrarily']['deep']['dictionary'] = "yes!"
print d['an']['arbitrarily']['deep']['dictionary']
To dump to a file: marko.coffee -x try.python.md > try.py
To extract and run: marko.coffee -x try.python.md | python -s
	% marko.coffee -x try.python.md > try.py
	% python try.py
	hello world!
	yes!
	% marko.coffee -x try.python.md \| python -s
	hello world!
	yes!
	#!/usr/bin/env coffee

	help = '''

	marko [options] FILES

	options:

	-h, --help show help
	-r, --run run code blocks
	-x, --extract extract code blocks

	'''

	fs = require 'fs'
	coffee = require 'coffee-script'
	marked = require 'marked'
	argv = require('optimist')
	.boolean(['h', 'r', 'x'])
	.alias('h', 'help')
	.alias('r', 'run')
	.alias('x', 'extract')
	.argv

	print = console.log
	print help if argv.help

	head = '''
	<!DOCTYPE html>
	<meta charset="utf-8">
	<link rel="stylesheet" href="style.css">
	<body>

	'''

	codeFrom = (source) ->
	(t.text for t in marked.lexer(source) when t.type == 'code').join "\n"

	for file in argv._ when file.match /\.(litcoffee\|md)/i
	source = fs.readFileSync file, 'utf8'
	if argv.run and /coffee/.test file
	coffee.eval codeFrom source
	else if argv.extract
	print codeFrom source
	else
	print head, marked source