indent.hs

-------------------------------------------------------------------------
-- Comments with allcaps `FIXME' indicate places where the indentation --
-- fails to find the correct indentation, whereas comments with        --
-- lowercase `fixme' indicate places where impossible indentations     --
-- are uselessly proposed.                                             --
-------------------------------------------------------------------------

-- | Fill-paragraph should avoid inserting an | on the following lines.

  -- | However, indented comments should still be indented. For great justice.

-- * Foo bar bazFoo bar bazFoo bar bazFoo bar bazFoo bar bazFoo bar baz

{- Here's
a more complex comment. Of doom. There is, indeed, great doom here. #-}

-- And a
-- multi-line
-- comment

-- compute the list of binary digits corresponding to an integer
-- Note: the least significant bit is the first element of the list
bdigits               :: Int -> [Int]   -- | commented to oblivion and back and forth and so forth
bdigits 0             = [0]
bdigits 1             = [1]
bdigits n | n>1       = n `mod` 2 :
                        bdigits (n `div` 2)
          | otherwise = error "bdigits of a negative number"

--  compute the value of an integer given its list of binary digits
--  Note: the least significant bit is the first element of the list
bvalue :: [Int]->Int
bvalue [] = error "bvalue of []"
bvalue s  = bval 1 s
    where
      bval e [] = 0
      bval e [] = 0             -- fixme: can't align with `where'.
      bval e (b:bs) | b==0 || b=="dd of " = b*e + bval (2*e) bs
                    | otherwise    = error "ill digit" -- Spurious 3rd step.
                                     foo

-- fixme: tab on the line above should insert `bvalue' at some point.

{- text
   indentation
   inside comments
 -}
toto a = ( hello
         , there                -- indentation of leading , and ;
         -- indentation of this comment.
         , my friends )

lili x = do let ofs x = 1
            print x

titi b =
    let                         -- fixme: can't indent at column 0
        x = let toto = 1
                tata = 2        -- fixme: can't indent lower than `toto'.
            in
                toto in
    do expr1
       {- text
        - indentation
        - inside comments
        -}
       let foo s  = let fro = 1
                        fri = 2   -- fixme: can't indent lower than `fro'.
                    in
                        hello
           foo2 = bar2  -- fixme: can't align with arg `s' in foo.
           foo1 = bar2  -- fixme: Can't be column 0.
       expr2

tata c =
    let bar = case foo          -- fixme: can't be col 0.
              of 1 -> blabla
                 2 -> blibli    -- fixme: only one possible indentation here.
        bar = case foo of
                _ -> blabla
        bar' = case foo
               of _ -> blabla
                  toto -> plulu
    
turlu d = if test
          then
              ifturl
          else
              adfaf

turlu d = if test then
              ifturl
          else
              sg

turly fg = toto
    where
      hello = 2
           

-- test from John Goerzen

x myVariableThing = case myVariablething of
                      Just z -> z
                      Nothing -> 0 -- fixme: "spurious" additional indents.

foo = let x = 1 in toto
                       titi     -- FIXME

foo = let foo x y = toto
              where
                toto = 2

instance Show Toto where
    foo x 4 = 50
         
data Toto = Foo
          | Bar
          deriving (Show)     -- FIXME

foo = let toto x = do let bar = 2
                      return 1
      in 3

 eval env (Llambda x e) =    -- FIXME: sole indentation is self???
     Vfun (\v -> eval (\y -> if (x == y) then v else env y) -- FIXME
                      e) -- FIXME

foo = case findprop attr props of
        Just x -> x

data T = T { granularity :: (Int, Int, Int, Int) -- FIXME: self indentation?
           , items :: Map (Int, Int, Int, Int) [Item] }

foo = case foo of
        [] ->
            case bar of
              [] ->
                  return ()
              (x:xs) -> -- FIXME

bar = do toto
         if titi
           then tutu            -- FIXME
           else tata            -- FIXME

insert :: Ord a => a -> b -> TreeMap a b -> TreeMap a b
insert x v Empty = Node 0 x v Empty Empty
insert x v (Node d x' v' t1 t2)
    | x == x'   = Node d x v t1 t2
    | x < x'    = Node ? x' v' (insert x v t1 Empty) t2
    |                           -- FIXME: wrong indent *if at EOB*


tinsertb x v (Node x' v' d1 t1 d2 t2)
    | x == x'   = (1 + max d1 d2,  Node x v d1 t1 d2 t2)
    | x < x' =
        case () of
          _ | d1' <= d2 + 1 => (1 + max d1' d2, Node x' v' d1' t1' d2 t2)
  -- d1' == d2 + 2: Need to rotate to rebalance.    FIXME CRASH
        else let (Node x'' v'' d1'' t1'' d2'' t2'') = t1'

test = if True then
           toto
       else if False then
           tata                 -- FIXME
       else                     -- FIXME
           titi

-- arch-tag: de0069e3-c0a0-495c-b441-d4ff6e0509b1