Take a function as arguement, and the function only return true of false.
If the function ‘f‘ return ture, when complement(f) will return false.
var isEven = n => n % 2 === 0; var isOdd = R.complement(isEven); isOdd(21); //=> true isOdd(42); //=> false
[Ramda] Complement: Logic opposite function
原文：http://www.cnblogs.com/Answer1215/p/5944386.html