Why doesn't this simple Curry-like implemention work?

[Eyal Lotem]

Michael R. Head wrote:

> # for some reason this function doesn't work in python 1.5.2.
> def curry(f, p):
> return lambda x: apply(f, p, x)

apply(f, p, x) is in the context of an internal function.  Without 
nested_scopes (optionally introduced in Python 2.1, and in by default in 
Python 2.2), internal functions cannot use containing-function's scopes.

Python 1.5 code:

def curry(f, p):
        return lambda x,f=f,p=p: apply(f, p, x)

or in Python 2.1:

from __future__ import nested_scopes

def curry(f, p):
        return lambda x: apply(f, p, x)

will work.
I would suggest considering moving to Python 2.1, as nested_scopes seem to 
be safer, at least for this case.  With the default-argument trick, you 
allow more arguments than you really want to allow, which could cause 
trouble.