Create a DSL in Python

dsl.py

import types
import re

buffer_regex = re.compile(r'^([\t\s]*)\w')

def dedent(code):
    replace_chunk = ''
    for line in code.split('\n'):
        matches = buffer_regex.search(line)
        if matches:
            replace_chunk = matches.group(1)
            break

    dedented_lines = []
    for line in code.split('\n'):
        dedented_lines.append(line.replace(replace_chunk, ''))
    return '\n'.join(dedented_lines)

def do(code):
    return compile(dedent(code), __file__, 'exec')

def it(name, code, data):
    for arg in data:
        types.FunctionType(code, arg, name)()

def data(*args):
    for arg in args:
        yield arg

output.txt

> python run_dsl.py
Greater
ZERO!
Less

run_dsl.py

#!/usr/bin/python
from dsl import it, do, data

if __name__ == '__main__':

    it('matthew', do("""
        if x > 0:
            print "Greater"
        elif x < 0:
            print "Less"
        else:
            print "ZERO!"
    """), data(
        dict(x=1),
        dict(x=0),
        dict(x=-1),
    ))