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lightweight contracts for python
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Simple, type-of-value based contracts for Python, as decorators.

For example, here's a method that takes a string, and returns a string.

@contract(str, str)
def exclaim(s):
    return s + '!'

exclaim('hello') # prints 'hello!'
exclaim(5)       # raises FailedContract

Here's a method that takes a string, and returns a method that takes a string and returns a string.

@contract(str, contract(str, str))
def prepender(s):
    @contract('(str,) -> str')
    def wrapper(s2):
        return s + s2
    return wrapper

prepender('hello, ')('dave') # prints 'hello, dave'
prepender(5)                 # raises FailedContract
prepender('hi')(5)           # raises FailedContract
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