This goes so far that the phrase "nobody knows" is described by grammarians as having a zero pronoun, ie. "nobody knows (it)". "it" doesn't need to be specified

This goes so far that the phrase "nobody knows" is described by grammarians as having a zero pronoun, ie. "nobody knows (it)". "it" doesn't need to be specified, because nobody would know what it is, and so nobody cares. Correspondingly, functional programmers use to write "f(_)" and in prolog for example that acts as a catch all glob operator, if I recall correctly, not sure about Haskell.