[Python-ideas] Symbolic expressions (or: partials and closures from the inside out)

[Carl M. Johnson]

You guys know this can more or less be done in Python today, right?

>>> class Symbolic:
...     def __init__(self, func=lambda x: x):
...         self.func = func
...     
...     def __call__(self, arg):
...         return self.func(arg)
...     
...     def __add__(self, other):
...         func = lambda x: self.func(x) + other
...         return Symbolic(func)
...     
...     __radd__ = __add__
...     
...     def __mul__(self, other):
...         func = lambda x: self.func(x) * other
...         return Symbolic(func)
...     
...     __rmul__ = __mul__
... 
>>> 
>>> X = Symbolic()
>>> Y = (2 * X) + 10
>>> Y(20)
50

I leave further extensions as an exercise for the reader, but it's not especially tricky to add various boolean tests and whatnot.

I don't claim any originality here. I'm fairly sure I read about this idea in blog post somewhere years ago.