Pretty instances for 4-tuples etc.

[vmchale]

I ran into this recently:

run/Main.hs:347:53: error: [GHC-39999]
    • No instance for ‘Prettyprinter.Internal.Pretty
                         (Apple Double, Apple Double, Apple Double, Double)’
        arising from a use of ‘pretty’
    • In the second argument of ‘($)’, namely ‘pretty (a0, a1, a2, f)’
      In the second argument of ‘($)’, namely
        ‘(<> hardline) $ pretty (a0, a1, a2, f)’
      In a stmt of a 'do' block:
        putDoc $ (<> hardline) $ pretty (a0, a1, a2, f)
    |
347 |                                 putDoc$(<>hardline)$pretty (a0, a1, a2, f)
    |                                                     ^^^^^^

Having more Pretty instances for tuples would be useful to me.

[sjakobi]

These instances have actually been written before: b52e320

Seems like there's an actual need for them!