View difference between Paste ID: TZ1REKUZ and 7CdZ5VPc

 (* Pretty-printing. *)
 local
   fun toStringh TRUE = "TRUE"
   |   toStringh FALSE = "FALSE"
   |   toStringh Var e = e
   |   toStringh Not e = "~" ^ noth e
   |   toStringh Or (e1, e2) = orh e1 ^ " | " ^ orh e2
   |   toStringh And (e1, e2) = andh e1 ^ " & " ^ andh e2
   |   toStringh Implies (e1, e2) = toStringh e1 ^ " -> " ^ toStringh e2
 
   and noth Or (e1, e2) = toStringh e1 ^ toStringh e2
   |   noth And (e1, e2) = toStringh e1 ^ toStringh e2
   |   noth Implies (e1, e2) = toStringh e1 ^ toStringh e2
 
   and andh Or (e1, e2) = toStringh e1 ^ toStringh e2
   |   andh Implies (e1, e2) = toStringh e1 ^ toStringh e2
 
   and orh Implies (e1, e2) = "(" ^ toStringh e1 ^ toStringh e2 ^ ")"
 
 in
   fun toString e = toStringh e
 end