main.ts

import { one, two, pipe } from './utils';

class Main {
  public sentence() {
    return pipe<string>('word', 
      addPeriod, 
      capitalize);
  }
}

utils.ts

export function pipe<T>(state: T, ...fns): T {
  return fns.reduce(function (state: T, fn: (T) => T) {
    return fn(state)
  }, state);
}

export function addPeriod(value: string) {
  return value + '.';
}

export function capitalize(value: string) {
  return value.charAt(0).toUpperCase() + value.substr(1);
}