(b: Block) doc := Pretty clone join: b

Pretty needs-parens?: Block := False
Pretty needs-parens?: Boolean := False
Pretty needs-parens?: Character := False
Pretty needs-parens?: Continuation := False
Pretty needs-parens?: Double := False
Pretty needs-parens?: Expression := False
Pretty needs-parens?: Haskell := False
Pretty needs-parens?: Integer := False
Pretty needs-parens?: List := False
Pretty needs-parens?: Message := False
Pretty needs-parens?: Method := False
Pretty needs-parens?: Particle := False
Pretty needs-parens?: Pattern := False
Pretty needs-parens?: Process := False
Pretty needs-parens?: Rational := False
Pretty needs-parens?: Regexp := False
Pretty needs-parens?: String := False
Pretty needs-parens?: Tuple := False
Pretty needs-parens?: _  := True

x pretty-parens :=
  { if: (needs-parens?: x)
      then: { parens: x pretty }
      else: { x pretty }
  } doc