text: 'use strict';
  
  const S = require ('..');
  
  const eq = require ('./internal/eq');
  
  
  test ('sub', () => {
  
    eq (typeof S.sub) ('function');
    eq (S.sub.length) (1);
    eq (S.show (S.sub)) ('sub :: FiniteNumber -> FiniteNumber -> FiniteNumber');
  
    eq (S.map (S.sub (1)) ([1, 2, 3])) ([0, 1, 2]);
  
  });
  