The exercise is to implement various functions for use with rational numbers. One of the functions is named ‘abs’ and should return the absolute value of a rational number.

I’m not trying to use the Kernel.abs function. When the code is interpreted it gets to the ‘abs’ function definition that is supposed to be implemented as a part of the solution to the exercise and it raises the error for the conflict.

I am not importing Kernel, so I have to assume that it gets imported behind the scenes when the tests are ran for this exercise

defmodule RationalNumbers do
@type rational :: {integer, integer}
@doc """
Add two rational numbers
"""
@spec add(a :: rational, b :: rational) :: rational
def add(a, b) do
{a_num, a_den} = a
{b_num, b_den} = b
x = a_num * b_den + b_num * a_den
y = a_den * b_den
reduce({x, y})
end
@doc """
Subtract two rational numbers
"""
@spec subtract(a :: rational, b :: rational) :: rational
def subtract(a, b) do
{a_num, a_den} = a
{b_num, b_den} = b
x = a_num * b_den - b_num * a_den
y = a_den * b_den
reduce({x, y})
end
@doc """
Multiply two rational numbers
"""
@spec multiply(a :: rational, b :: rational) :: rational
def multiply(a, b) do
{a_num, a_den} = a
{b_num, b_den} = b
x = (a_num * a_den)
y = (b_num * b_den)
reduce({x, y})
end
@doc """
Divide two rational numbers
"""
@spec divide_by(num :: rational, den :: rational) :: rational
def divide_by(num, den) do
{num_a, num_b} = num
{den_a, den_b} = den
x = num_a * den_b
y = num_b * den_a
reduce({x, y})
end
@doc """
Absolute value of a rational number
"""
@spec abs(a :: rational) :: rational
def abs(a) do
IO.puts(a)
end
@doc """
Exponentiation of a rational number by an integer
"""
@spec pow_rational(a :: rational, n :: integer) :: rational
def pow_rational(a, n) do
{a, n}
end
@doc """
Exponentiation of a real number by a rational number
"""
@spec pow_real(x :: integer, n :: rational) :: float
def pow_real(x, n) do
{x, n}
end
@doc """
Reduce a rational number to its lowest terms
"""
@spec reduce(a :: rational) :: rational
def reduce(a) do
{a1, a2} = a
gcd = Integer.gcd(abs(a1), abs(a2))
{div(a1, gcd), div(a2, gcd)}
end
end