HW--Church numerals

The logician Alonzo Church invented a system of representing non-negative integers entirely using functions. Here are the definitions of 0, and a function that returns 1 more than its argument:

def zero(f):
    return lambda x: x

def successor(n):
    return lambda f: lambda x: f(n(f)(x))

This representation is known as  Church numerals . Define  one  and  two  directly, which are also functions. To get started, apply  successor  to  zero . Then, give a direct definition of the  add  function (not in terms of repeated application of  successor ) over Church numerals. Finally, implement a function  church_to_int  that converts a church numeral argument to a regular Python int.


Solution:

def one(f):
    return successor(zero)(f)
def two(f):
    return successor(one)(f)

def add(m,n,f):
    return lambda x: m(f)(n(f)(x))

def church_to_int(m,f,x):
    tmp=zero
    n=0
    while tmp(f)(x)!=m(f)(x):
        tmp=successor(tmp)
        n=n+1
    return n


Not so sure whether I can code like this.









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