Remove rest parameters from equals

[johannes-lindgren]

equals accept rest parameters:

equals('red', 'green', 'blue')

The question is: should we limit the number of arguments to exactly 1? For the example above, this would mean:

oneOf(
  equals('red'),
  equals('green'),
  equals('blue'),
)

It's more repetitive, but equals is mostly meant to be used for discriminated unions. Having exactly one argument would add simplicity and constitency.