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## Data Abstraction
 
# Variable Naming
# The key idea behind data abstraction is that we want to give meaning to data types. We already have 
# seen how the naming your variables more meaninfully would help us give meaning to primitive data. 
# For instance,

x = 24                # Not exactly clear what x refers to, and what does 24 mean

# Consider:

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# For this question, you are suppose to create a poly generator function, that would create
# a *function* that when passed in a value x, calculate the polynomial of using the coefficient
# that was used when the function is created.

# In short, we are given this function has already been defined for us:
def poly(coefficient, x):
  # returns the following:
  # (coeff[0] * x^0) + (coeff[1] * x^1) + (coeff[2] * x^2) + ...
  
# and we want to create a function which would create a function that looks like the above, but has fixed

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# GCD HOF Question

# For the filtered accumulate function, notice that the filtered function takes in 1 parameter, the
# term number, and returns True/False, depending on whether we want to accept the term or not.
# For the prime question, we can directly use the same is_prime function, because it takes in 
# a number, and returns True if it is prime, and False otherwise. Since we want to sum the square
# of the prime numbers between a and b, is_prime works well as the filtered function.

# For the GCD question, it is not that straightforward. The function that is provided to us, gcd, 
# takes in 2 values, and worse, it returns an integer which describes the GCD of the 2 numbers.

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def bank_account(balance):
    # Inner functions are created in the scope of the
    # outer function, and as such have 'knowledge' of
    # the scope.
    #
    # In this case, it knows about the balance.
    # This function returns a string telling us
    # whether the owner is rich or poor
    def are_you_rich():
        # The inner function can access/read the variables

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    NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString* documentsDirectory = [paths objectAtIndex:0];
    
    NSString *plistfile = [documentsDirectory stringByAppendingString:@"Global.plist"];
    
    
    NSDictionary *dictionaryToSerialize = @{@"Hello": @"World", @"Dictionary": @{@"InnerHello": @"InnerWorld"}};
    [dictionaryToSerialize writeToFile:plistfile atomically:YES];