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July 26, 2008, at 12:12 PM by hodge - Fixed fatal flaw.

Added lines 6-7:

Update: The initial version (see history) had a fatal flaw—the argument list was shared between all versions of the curried function. The new version fixes this (and adds better testing :).

Changed lines 9-10 from:

An attempt at implementing currying in Python.

to:

"""An attempt at implementing currying in Python."""

Changed lines 14-24 from:

    def __init__(self, f):
        args, varargs, varkw, defaults = inspect.getargspec(f)

        self._f = f
        self._n = len(args)
        self._arg_values = []

    def __call__(self, *args):
        self._arg_values.extend(args)
        if len(self._arg_values) >= self._n:
            return self._f(*self._arg_values)

to:

    def __init__(self, func, arg_names=None, arg_values=None):
        self.func = func

        if arg_names is None:
            args, varargs, varkw, defaults = inspect.getargspec(self.func)
            self.arg_names = args

Changed lines 21-32 from:

            return self

def f(x,y):

    return x + y

cf = Curry(f) print cf(5)(6)

def g(x,y,z,w):

    return (x - y) + (z - w)

cg = Curry(g) print cg(6)(5)(4)(3)

to:

            self.arg_names = arg_names

        if arg_values is None:
            self.arg_values = ()
        else:
            self.arg_values = arg_values

    def __call__(self, *params):
        new_params = self.arg_values + params
        if len(new_params) >= len(self.arg_names):
            return self.func(*new_params)
        else:
            return Curry(self.func, arg_names=self.arg_names,
                         arg_values=new_params)

if __name__ == "__main__":

    print "Running some basic tests ..."

    def f(x,y):
        return x + y
    cf = Curry(f)

    cf_5 = cf(5)
    cf_10 = cf(10)

    assert cf(5)(6) == 11
    assert cf_5(7) == 12
    assert cf_10(12) == 22

    def g(x,y,z,w):
        return (x - y) + (z - w)
    cg = Curry(g)

    cg_2_1 = cg(2)(1)
    cg_3_4_5 = cg(3)(4)(5)
    cg_12 = cg(12)

    assert cg(4)(3)(2)(1) == 2
    assert cg_2_1(7)(5) == 3
    assert cg_3_4_5(12) == -8
    assert cg_12(2)(8)(4) == 14

Restore

July 24, 2008, at 03:30 PM by hodge - Curry?

Added lines 1-36:

Python Curry

24 July 2008

See the wikipedia article on Currying for an explanation of the basic concept.

=python # An attempt at implementing currying in Python. import inspect class Curry(object): def __init__(self, f): args, varargs, varkw, defaults = inspect.getargspec(f) self._f = f self._n = len(args) self._arg_values = [] def __call__(self, *args): self._arg_values.extend(args) if len(self._arg_values) >= self._n: return self._f(*self._arg_values) else: return self def f(x,y): return x + y cf = Curry(f) print cf(5)(6) def g(x,y,z,w): return (x - y) + (z - w) cg = Curry(g) print cg(6)(5)(4)(3)

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