until transducer: reduce_sum_reduce

sum_of_every_element.test.ts

import { sum_of_every_element } from './sum_of_every_element'

test('calculate the sum of all elements using reduce', () => {

  expect(sum_of_every_element([1, 2, 3])).toEqual(6)

})

sum_of_every_element.ts

import { reduce } from 'ramda'

export const sum_of_every_element =
  reduce(
    (previous: number, current: number) => previous + current,
    0
  )