CurryInfo: icurry-3.2.0 / ICurry.Graph.showGraphExp

showGraphExp :: Graph -> NodeID -> String
showGraphExp g nid = showExp [] 10 nid
 where
  showExp lets d ni | d == 0    = "..."
                    | otherwise = showNExp (lookupNode ni g)
   where
    showNExp FreeNode             = "_x" ++ show ni
    showNExp (ConsNode f args)    = showNExp (FuncNode f args)
    showNExp (PartNode f _ args)  = showNExp (FuncNode f args)
    showNExp (ChoiceNode c n1 n2) = showNExp (FuncNode ('?' : show c) [n1,n2])
    showNExp (FuncNode f args)
      | null args = f
      | otherwise
      = "(" ++
        (if null arglets
           then ""
           else "let {" ++
                intercalate " ; " (map showLetDecl arglets) ++ "} in ") ++
        showCall (map (\a -> if a `elem` alllets
                               then showVar a
                               else showExp alllets (d-1) a) args) ++
        ")"
     where
      showCall cargs =
        if isInfixOp f
          then case cargs of
                 [a1,a2] -> unwords [a1,f,a2]
                 _       -> unwords (('(' : f ++ ")") : cargs)
          else unwords (f : cargs)
       where
        isInfixOp = all (`elem` "!@#$%^&*+-=<>?./|\\:")

      arglets = nub (concatMap
                       (\a -> let occs = occursInGraphExp d a ni
                              in if occs < 2 || isConst a then [] else [a])
                       (filter (`notElem` lets) args))

      alllets = arglets ++ lets

      showLetDecl a = showVar a ++ " = " ++ showExp alllets (d-1) a

  showVar ni = 'x' : show ni

  isConst ni = case lookupNode ni g of
        ConsNode _ [] -> True
        _             -> False

  -- count occurrences of a node `ni` in graph rooted by `nr`
  occursInGraphExp d ni nr
    | d == 0 = 0
    | otherwise
    = (if ni==nr then 1 else 0) +
      case lookupNode nr g of
        FuncNode _   args  -> foldr (+) 0 (map (occursInGraphExp (d-1) ni) args)
        ConsNode _   args  -> foldr (+) 0 (map (occursInGraphExp (d-1) ni) args)
        PartNode _ _ args  -> foldr (+) 0 (map (occursInGraphExp (d-1) ni) args)
        ChoiceNode _ a1 a2 -> occursInGraphExp (d-1) ni a1 +
                              occursInGraphExp (d-1) ni a2
        FreeNode           -> 0

arguments 1 2

deterministic operation

-- Shows the expression represented by the graph starting with a given node.
-- In order to visualize sharing, shared subexpressions are shown
-- as let expressions.

(_, _)

referentially transparent operation

no fixity defined

{(_,_) |-> _}

showGraphExp

no precedence defined

_

Graph -> Prelude.Int -> String

operation might suspend on free variables

possibly non-terminating

possibly non-reducible on same data term