Add inline documentation to types:

fifo
  :: Clock dom
  -> Reset dom
  -> SNat addrSize
  -> "read request" ::: Signal dom Bool
  -> "write request" ::: Signal dom (Maybe (BitVector dataSize))
  -> ( "q"     ::: Signal dom (BitVector dataSize)
     , "full"  ::: Signal dom Bool
     , "empty" ::: Signal dom Bool
     )

which can subsequently be inspected in the interactive environment:

>>> import Clash.Explicit.Prelude
>>> :t fifo @System
fifo @System
  :: Clock System
     -> Reset System
     -> SNat addrSize
     -> ("read request" ::: Signal System Bool)
     -> ("write request" ::: Signal System (Maybe (BitVector dataSize)))
     -> ("q" ::: Signal System (BitVector dataSize),
         "full" ::: Signal System Bool, "empty" ::: Signal System Bool)