packages feed

blunt (empty) → 0.0.1

raw patch · 12 files changed

+1545/−0 lines, 12 filesdep +arraydep +basedep +bluntsetup-changed

Dependencies added: array, base, blunt, bytestring, containers, haskell-src-exts, http-types, transformers, wai, warp

Files

+ LICENSE.md view
@@ -0,0 +1,21 @@+The MIT License (MIT)++Copyright (c) 2015 Taylor Fausak <taylor@fausak.me>++Permission is hereby granted, free of charge, to any person obtaining a copy+of this software and associated documentation files (the "Software"), to deal+in the Software without restriction, including without limitation the rights+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell+copies of the Software, and to permit persons to whom the Software is+furnished to do so, subject to the following conditions:++The above copyright notice and this permission notice shall be included in+all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN+THE SOFTWARE.
+ Setup.hs view
@@ -0,0 +1,6 @@+module Main (main) where++import Distribution.Simple (defaultMain)++main :: IO ()+main = defaultMain
+ blunt.cabal view
@@ -0,0 +1,52 @@+name: blunt+version: 0.0.1+cabal-version: >=1.10+build-type: Simple+license: MIT+license-file: LICENSE.md+maintainer: Taylor Fausak <taylor@fausak.me>+synopsis: Point-free Haskell as a service.+description:+    TODO+category: Web++source-repository head+    type: git+    location: https://bitbucket.org/taylorfausak/blunt++library+    exposed-modules:+        Blunt+    build-depends:+        base ==4.*,+        bytestring -any,+        http-types -any,+        wai -any,+        warp ==3.*+    default-language: Haskell2010+    hs-source-dirs: library+    ghc-options: -Wall++    -- pointfree+    build-depends:+        array,+        containers,+        haskell-src-exts,+        transformers+    other-modules:+        Pointfree+        Plugin.Pl.Common+        Plugin.Pl.Parser+        Plugin.Pl.PrettyPrinter+        Plugin.Pl.Optimize+        Plugin.Pl.Rules+        Plugin.Pl.Transform++executable blunt+    main-is: Main.hs+    build-depends:+        base ==4.*,+        blunt -any+    default-language: Haskell2010+    hs-source-dirs: executable+    ghc-options: -Wall
+ executable/Main.hs view
@@ -0,0 +1,3 @@+module Main (main) where++import Blunt (main)
+ library/Blunt.hs view
@@ -0,0 +1,63 @@+{-# LANGUAGE OverloadedStrings #-}++module Blunt where++import Data.ByteString.Char8 (unpack)+import Data.ByteString.Lazy (fromStrict)+import Data.ByteString.Lazy.Char8 (pack)+import Network.HTTP.Types (notFound404, ok200)+import Network.Wai (queryString, pathInfo, requestMethod, responseLBS)+import Network.Wai.Handler.Warp (run)+import Pointfree (pointfree')++main :: IO ()+main = run 8080 $ \ request respond -> do+    let method = requestMethod request+        path = pathInfo request+        response = case (method, path) of+            ("GET", []) -> responseLBS ok200 [("Content-Type", "text/html; charset=utf-8")] $ pack $ unlines+                [ "<!doctype html>"+                , ""+                , "<html>"+                , "  <head>"+                , "    <title>Pointfree</title>"+                , "  </head>"+                , ""+                , "  <body>"+                , "    <input id='input' autofocus>"+                , "    <input id='output' readonly>"+                , ""+                , "    <script>"+                , "      'use strict';"+                , ""+                , "      (function () {"+                , "        var input = document.getElementById('input');"+                , "        var output = document.getElementById('output');"+                , ""+                , "        input.oninput = function (event) {"+                , "          var request = new XMLHttpRequest();"+                , "          request.onreadystatechange = function () {"+                , "            if (request.readyState === 4 && request.status === 200) {"+                , "              output.value = request.response;"+                , "            }"+                , "          };"+                , "          request.open('GET', '/pointfree?input=' + encodeURIComponent(input.value));"+                , "          request.send();"+                , "        };"+                , "      }());"+                , "    </script>"+                , "  </body>"+                , "</html>"+                ]+            ("GET", ["pointfree"]) ->+                let params = queryString request+                    input = case lookup "input" params of+                        Just (Just param) -> param+                        _ -> ""+                    maybeOutput = pointfree' (unpack input)+                    body = case maybeOutput of+                        Just output -> pack output+                        Nothing -> fromStrict input+                in  responseLBS ok200 [("Content-Type", "text/plain; charset=utf-8")] body+            _ -> responseLBS notFound404 [] ""+    respond response
+ library/Plugin/Pl/Common.hs view
@@ -0,0 +1,144 @@+module Plugin.Pl.Common (+        Fixity(..), Expr(..), Pattern(..), Decl(..), TopLevel(..),+        bt, sizeExpr, mapTopLevel, mapTopLevel', getExpr,+        operators, reservedOps, lookupOp, lookupFix, minPrec, maxPrec,+        comp, flip', id', const', scomb, cons, nil, fix', if', readM,+        makeList, getList,+        Assoc(..),+        module Data.Maybe,+        module Control.Arrow,+        module Data.List,+        module Control.Monad,+        module GHC.Base+    ) where++import Data.Maybe (isJust, fromJust)+import Data.List (intersperse, minimumBy)+import qualified Data.Map as M++import Control.Monad+import Control.Arrow (first, second, (***), (&&&), (|||), (+++))++import Language.Haskell.Exts (Assoc(..))++import GHC.Base (assert)+++-- The rewrite rules can be found at the end of the file Rules.hs++-- Not sure if passing the information if it was used as infix or prefix+-- is worth threading through the whole thing is worth the effort,+-- but it stays that way until the prettyprinting algorithm gets more+-- sophisticated.+data Fixity = Pref | Inf deriving Show++instance Eq Fixity where+  _ == _ = True++instance Ord Fixity where+  compare _ _ = EQ++data Expr+  = Var Fixity String+  | Lambda Pattern Expr+  | App Expr Expr+  | Let [Decl] Expr+  deriving (Eq, Ord, Show)++data Pattern+  = PVar String +  | PCons Pattern Pattern+  | PTuple Pattern Pattern+  deriving (Eq, Ord, Show)++data Decl = Define { +  declName :: String, +  declExpr :: Expr+} deriving (Eq, Ord, Show)++data TopLevel = TLD Bool Decl | TLE Expr deriving (Eq, Ord, Show)++mapTopLevel :: (Expr -> Expr) -> TopLevel -> TopLevel+mapTopLevel f tl = case getExpr tl of (e, c) -> c $ f e++mapTopLevel' :: Functor f => (Expr -> f Expr) -> TopLevel -> f TopLevel+mapTopLevel' f tl = case getExpr tl of (e, c) -> fmap c $ f e++getExpr :: TopLevel -> (Expr, Expr -> TopLevel)+getExpr (TLD True (Define foo e)) = (Let [Define foo e] (Var Pref foo), +                                     \e' -> TLD False $ Define foo e')+getExpr (TLD False (Define foo e)) = (e, \e' -> TLD False $ Define foo e')+getExpr (TLE e)      = (e, TLE)++sizeExpr :: Expr -> Int+sizeExpr (Var _ _) = 1+sizeExpr (App e1 e2) = sizeExpr e1 + sizeExpr e2 + 1+sizeExpr (Lambda _ e) = 1 + sizeExpr e+sizeExpr (Let ds e) = 1 + sum (map sizeDecl ds) + sizeExpr e where+  sizeDecl (Define _ e') = 1 + sizeExpr e'++comp, flip', id', const', scomb, cons, nil, fix', if' :: Expr+comp   = Var Inf  "."+flip'  = Var Pref "flip"+id'    = Var Pref "id"+const' = Var Pref "const"+scomb  = Var Pref "ap"+cons   = Var Inf  ":"+nil    = Var Pref "[]"+fix'   = Var Pref "fix"+if'    = Var Pref "if'"++makeList :: [Expr] -> Expr+makeList = foldr (\e1 e2 -> cons `App` e1 `App` e2) nil++-- Modularity is a drag+getList :: Expr -> ([Expr], Expr)+getList (c `App` x `App` tl) | c == cons = first (x:) $ getList tl+getList e = ([],e)++bt :: a+bt = undefined++shift, minPrec, maxPrec :: Int+shift = 0+maxPrec = shift + 10+minPrec = 0++-- operator precedences are needed both for parsing and prettyprinting+operators :: [[(String, (Assoc, Int))]]+operators = (map . map . second . second $ (+shift))+  [[inf "." AssocRight 9, inf "!!" AssocLeft 9],+   [inf name AssocRight 8 | name <- ["^", "^^", "**"]],+   [inf name AssocLeft 7+     | name <- ["*", "/", "`quot`", "`rem`", "`div`", "`mod`", ":%", "%"]],+   [inf name AssocLeft 6  | name <- ["+", "-"]],+   [inf name AssocRight 5 | name <- [":", "++"]],+   [inf name AssocNone 4 +     | name <- ["==", "/=", "<", "<=", ">=", ">", "`elem`", "`notElem`"]],+   [inf "&&" AssocRight 3],+   [inf "||" AssocRight 2],+   [inf ">>" AssocLeft 1, inf ">>=" AssocLeft 1, inf "=<<" AssocRight 1],+   [inf name AssocRight 0 | name <- ["$", "$!", "`seq`"]]+  ] where+  inf name assoc fx = (name, (assoc, fx))++reservedOps :: [String]+reservedOps = ["->", "..", "="]++opFM :: M.Map String (Assoc, Int)+opFM = (M.fromList $ concat operators)++lookupOp :: String -> Maybe (Assoc, Int)+lookupOp k = M.lookup k opFM++lookupFix :: String -> (Assoc, Int)+lookupFix str = case lookupOp $ str of+  Nothing -> (AssocLeft, 9 + shift)+  Just x  -> x++readM :: (Monad m, Read a) => String -> m a+readM s = case [x | (x,t) <- reads s, ("","")  <- lex t] of+            [x] -> return x+            []  -> fail "readM: No parse."+            _   -> fail "readM: Ambiguous parse."+
+ library/Plugin/Pl/Optimize.hs view
@@ -0,0 +1,104 @@+{-# LANGUAGE ImplicitParams #-}+module Plugin.Pl.Optimize (+    optimize,+  ) where++import Plugin.Pl.Common+import Plugin.Pl.Rules+import Plugin.Pl.PrettyPrinter (prettyExpr)++import Data.List (nub)++cut :: [a] -> [a]+cut = take 1++toMonadPlus :: MonadPlus m => Maybe a -> m a+toMonadPlus Nothing = mzero+toMonadPlus (Just x)= return x++type Size = Integer+-- This seems to be a better size for our purposes,+-- despite being "a little" slower because of the wasteful uglyprinting+sizeExpr' :: Expr -> Size +sizeExpr' e = 100 * fromIntegral (length $ prettyExpr e) + adjust e where+  -- hackish thing to favor some expressions if the length is the same:+  -- (+ x) --> (x +)+  -- x >>= f --> f =<< x+  -- f $ g x --> f (g x)+  adjust :: Expr -> Size+  adjust (Var _ str) -- Just n <- readM str = log (n*n+1) / 4+                     | str == "uncurry"    = -400+--                     | str == "s"          = 500+                     | str == "flip"       = 10+                     | str == ">>="        = 5+                     | str == "$"          = 1+                     | str == "subtract"   = 1+                     | str == "ap"         = 200+                     | str == "liftM2"     = 101+                     | str == "return"     = -200+                     | str == "zipWith"    = -400+                     | str == "const"      = 0 -- -200+                     | str == "fmap"       = -100+  adjust (Lambda _ e') = adjust e'+  adjust (App e1 e2)  = adjust e1 + adjust e2+  adjust _ = 0++optimize :: Expr -> [Expr]+optimize e = result where+  result :: [Expr]+  result = map (snd . fromJust) . takeWhile isJust . +    iterate ((=<<) simpleStep) $ Just (sizeExpr' e, e)++  simpleStep :: (Size, Expr) -> Maybe (Size, Expr)+  simpleStep t = do +    let chn = let ?first = True in step (snd t)+        chnn = let ?first = False in step =<< chn+        new = filter (\(x,_) -> x < fst t) . map (sizeExpr' &&& id) $ +                snd t: chn ++ chnn+    case new of+      [] -> Nothing+      (new':_) -> return new'++step :: (?first :: Bool) => Expr -> [Expr]+step e = nub $ rewrite rules e+ +rewrite :: (?first :: Bool) => RewriteRule -> Expr -> [Expr]+rewrite rl e = case rl of+    Up r1 r2     -> let e'  = cut $ rewrite r1 e+                        e'' = rewrite r2 =<< e'+                    in if null e'' then e' else e''+    OrElse r1 r2 -> let e'  = rewrite r1 e+                    in if null e' then rewrite r2 e else e' +    Then r1 r2   -> rewrite r2 =<< nub (rewrite r1 e)+    Opt  r       -> e: rewrite r e+    If   p  r    -> if null (rewrite p e) then mzero else rewrite r e+    Hard r       -> if ?first then rewrite r e else mzero+    Or rs        -> (\x -> rewrite x e) =<< rs+    RR {}        -> rewDeep rl e+    CRR {}       -> rewDeep rl e+    Down {}      -> rewDeep rl e+    +  where -- rew = ...; rewDeep = ...++rewDeep :: (?first :: Bool) => RewriteRule -> Expr -> [Expr]+rewDeep rule e = rew rule e `mplus` case e of+    Var _ _    -> mzero+    Lambda _ _ -> error "lambda: optimizer only works for closed expressions"+    Let _ _    -> error "let: optimizer only works for closed expressions"+    App e1 e2  -> ((`App` e2) `map` rewDeep rule e1) `mplus`+                  ((e1 `App`) `map` rewDeep rule e2)++rew :: (?first :: Bool) => RewriteRule -> Expr -> [Expr]+rew (RR r1 r2) e = toMonadPlus $ fire r1 r2 e +rew (CRR r) e = toMonadPlus $ r e+rew (Or rs) e = (\x -> rew x e) =<< rs+rew (Down r1 r2) e+  = if null e'' then e' else e'' where+    e'  = cut $ rew r1 e+    e'' = rewDeep r2 =<< e'+rew r@(Then   {}) e = rewrite r e+rew r@(OrElse {}) e = rewrite r e+rew r@(Up     {}) e = rewrite r e+rew r@(Opt    {}) e = rewrite r e+rew r@(If     {}) e = rewrite r e+rew r@(Hard   {}) e = rewrite r e
+ library/Plugin/Pl/Parser.hs view
@@ -0,0 +1,91 @@+module Plugin.Pl.Parser (parsePF) where++import Plugin.Pl.Common++import qualified Language.Haskell.Exts as HSE++todo :: (Show e) => e -> a+todo thing = error ("pointfree: not supported: " ++ show thing)++nameString :: HSE.Name -> (Fixity, String)+nameString (HSE.Ident s) = (Pref, s)+nameString (HSE.Symbol s) = (Inf, s)++qnameString :: HSE.QName -> (Fixity, String)+qnameString (HSE.Qual m n) = fmap (HSE.prettyPrint m ++) (nameString n)+qnameString (HSE.UnQual n) = nameString n+qnameString (HSE.Special sc) = case sc of+  HSE.UnitCon -> (Pref, "()")+  HSE.ListCon -> (Pref, "[]")+  HSE.FunCon -> (Inf, "->")+  HSE.TupleCon HSE.Boxed n -> (Inf, replicate (n-1) ',')+  HSE.TupleCon{} -> todo sc+  HSE.Cons -> (Inf, ":")+  HSE.UnboxedSingleCon -> todo sc++opString :: HSE.QOp -> (Fixity, String)+opString (HSE.QVarOp qn) = qnameString qn+opString (HSE.QConOp qn) = qnameString qn++list :: [Expr] -> Expr+list = foldr (\y ys -> cons `App` y `App` ys) nil++hseToExpr :: HSE.Exp -> Expr+hseToExpr expr = case expr of+  HSE.Var qn -> uncurry Var (qnameString qn)+  HSE.IPVar{} -> todo expr+  HSE.Con qn -> uncurry Var (qnameString qn)+  HSE.Lit l -> case l of+    HSE.String s -> list (map (Var Pref . show) s)+    _ -> Var Pref (HSE.prettyPrint l)+  HSE.InfixApp p op q -> apps (Var Inf (snd (opString op))) [p,q]+  HSE.App f x -> hseToExpr f `App` hseToExpr x+  HSE.NegApp e -> Var Pref "negate" `App` hseToExpr e+  HSE.Lambda _ ps e -> foldr (Lambda . hseToPattern) (hseToExpr e) ps+  HSE.Let bs e -> case bs of+    HSE.BDecls ds -> Let (map hseToDecl ds) (hseToExpr e)+    HSE.IPBinds ips -> todo ips+  HSE.If b t f -> apps if' [b,t,f]+  HSE.Case{} -> todo expr+  HSE.Do{} -> todo expr+  HSE.MDo{} -> todo expr+  HSE.Tuple HSE.Boxed es -> apps (Var Inf (replicate (length es - 1) ','))  es+  HSE.TupleSection{} -> todo expr+  HSE.List xs -> list (map hseToExpr xs)+  HSE.Paren e -> hseToExpr e+  HSE.LeftSection l op -> Var Inf (snd (opString op)) `App` hseToExpr l+  HSE.RightSection op r -> flip' `App` Var Inf (snd (opString op)) `App` hseToExpr r+  HSE.RecConstr{} -> todo expr+  HSE.RecUpdate{} -> todo expr+  HSE.EnumFrom x -> apps (Var Pref "enumFrom") [x]+  HSE.EnumFromTo x y -> apps (Var Pref "enumFromTo") [x,y]+  HSE.EnumFromThen x y -> apps (Var Pref "enumFromThen") [x,y]+  HSE.EnumFromThenTo x y z -> apps (Var Pref "enumFromThenTo") [x,y,z]+  _ -> todo expr++apps :: Expr -> [HSE.Exp] -> Expr+apps f xs = foldl (\a x -> a `App` hseToExpr x) f xs ++hseToDecl :: HSE.Decl -> Decl+hseToDecl dec = case dec of+  HSE.PatBind _ (HSE.PVar n) (HSE.UnGuardedRhs e) (HSE.BDecls []) ->+    Define (snd (nameString n)) (hseToExpr e)+  HSE.FunBind [HSE.Match _ n ps Nothing (HSE.UnGuardedRhs e) (HSE.BDecls [])] ->+    Define (snd (nameString n)) (foldr (\p x -> Lambda (hseToPattern p) x) (hseToExpr e) ps)+  _ -> todo dec++hseToPattern :: HSE.Pat -> Pattern+hseToPattern pat = case pat of+  HSE.PVar n -> PVar (snd (nameString n))+  HSE.PInfixApp l (HSE.Special HSE.Cons) r -> PCons (hseToPattern l) (hseToPattern r)+  HSE.PTuple HSE.Boxed [p,q] -> PTuple (hseToPattern p) (hseToPattern q)+  HSE.PParen p -> hseToPattern p+  HSE.PWildCard -> PVar "_"+  _ -> todo pat++parsePF :: String -> Either String TopLevel+parsePF inp = case HSE.parseExp inp of+  HSE.ParseOk e -> Right (TLE (hseToExpr e))+  HSE.ParseFailed _ _ -> case HSE.parseDecl inp of+    HSE.ParseOk d -> Right (TLD True (hseToDecl d))+    HSE.ParseFailed _ err -> Left err
+ library/Plugin/Pl/PrettyPrinter.hs view
@@ -0,0 +1,150 @@+{-# LANGUAGE PatternGuards #-}+module Plugin.Pl.PrettyPrinter (+  prettyDecl,+  prettyExpr,+  prettyTopLevel,+ ) where++import Plugin.Pl.Common++import Data.Char+import Data.List (intercalate)++prettyDecl :: Decl -> String+prettyDecl (Define f e) = f ++ " = " ++ prettyExpr e++prettyDecls :: [Decl] -> String+prettyDecls = intercalate "; " . map prettyDecl++prettyExpr :: Expr -> String+prettyExpr = show . toSExpr++prettyTopLevel :: TopLevel -> String+prettyTopLevel (TLE e) = prettyExpr e+prettyTopLevel (TLD _ d) = prettyDecl d++data SExpr+  = SVar !String+  | SLambda ![Pattern] !SExpr+  | SLet ![Decl] !SExpr+  | SApp !SExpr !SExpr+  | SInfix !String !SExpr !SExpr+  | LeftSection !String !SExpr  -- (x +)+  | RightSection !String !SExpr -- (+ x)+  | List ![SExpr]+  | Tuple ![SExpr]+  | Enum !Expr !(Maybe Expr) !(Maybe Expr)++{-# INLINE toSExprHead #-}+toSExprHead :: String -> [Expr] -> Maybe SExpr+toSExprHead hd tl+  | all (==',') hd, length hd+1 == length tl +  = Just . Tuple . reverse $ map toSExpr tl+  | otherwise = case (hd,reverse tl) of+      ("enumFrom", [e])              -> Just $ Enum e Nothing   Nothing+      ("enumFromThen", [e,e'])       -> Just $ Enum e (Just e') Nothing+      ("enumFromTo", [e,e'])         -> Just $ Enum e Nothing   (Just e')+      ("enumFromThenTo", [e,e',e'']) -> Just $ Enum e (Just e') (Just e'')+      _                              -> Nothing++toSExpr :: Expr -> SExpr+toSExpr (Var _ v) = SVar v+toSExpr (Lambda v e) = case toSExpr e of+  (SLambda vs e') -> SLambda (v:vs) e'+  e'              -> SLambda [v] e'+toSExpr (Let ds e) = SLet ds $ toSExpr e+toSExpr e | Just (hd,tl) <- getHead e, Just se <- toSExprHead hd tl = se+toSExpr e | (ls, tl) <- getList e, tl == nil+  = List $ map toSExpr ls+toSExpr (App e1 e2) = case e1 of+  App (Var Inf v) e0 +    -> SInfix v (toSExpr e0) (toSExpr e2)+  Var Inf v | v /= "-"+    -> LeftSection v (toSExpr e2)++  Var _ "flip" | Var Inf v <- e2, v == "-" -> toSExpr $ Var Pref "subtract"+    +  App (Var _ "flip") (Var pr v)+    | v == "-"  -> toSExpr $ Var Pref "subtract" `App` e2+    | v == "id" -> RightSection "$" (toSExpr e2)+    | Inf <- pr, any (/= ',') v -> RightSection v (toSExpr e2)+  _ -> SApp (toSExpr e1) (toSExpr e2)++getHead :: Expr -> Maybe (String, [Expr])+getHead (Var _ v) = Just (v, [])+getHead (App e1 e2) = second (e2:) `fmap` getHead e1+getHead _ = Nothing++instance Show SExpr where+  showsPrec _ (SVar v) = (getPrefName v ++)+  showsPrec p (SLambda vs e) = showParen (p > minPrec) $ ('\\':) . +    foldr (.) id (intersperse (' ':) (map (prettyPrecPattern $ maxPrec+1) vs)) .+    (" -> "++) . showsPrec minPrec e+  showsPrec p (SApp e1 e2) = showParen (p > maxPrec) $+    showsPrec maxPrec e1 . (' ':) . showsPrec (maxPrec+1) e2+  showsPrec _ (LeftSection fx e) = showParen True $ +    showsPrec (snd (lookupFix fx) + 1) e . (' ':) . (getInfName fx++)+  showsPrec _ (RightSection fx e) = showParen True $ +    (getInfName fx++) . (' ':) . showsPrec (snd (lookupFix fx) + 1) e+  showsPrec _ (Tuple es) = showParen True $+    (concat `id` intersperse ", " (map show es) ++)+  +  showsPrec _ (List es) +    | Just cs <- mapM ((=<<) readM . fromSVar) es = shows (cs::String)+    | otherwise = ('[':) . +      (concat `id` intersperse ", " (map show es) ++) . (']':)+    where fromSVar (SVar str) = Just str+          fromSVar _          = Nothing+  showsPrec _ (Enum fr tn to) = ('[':) . showString (prettyExpr fr) . +    showsMaybe (((',':) . prettyExpr) `fmap` tn) . (".."++) . +    showsMaybe (prettyExpr `fmap` to) . (']':)+      where showsMaybe = maybe id (++)+  showsPrec _ (SLet ds e) = ("let "++) . showString (prettyDecls ds ++ " in ") . shows e+++  showsPrec p (SInfix fx e1 e2) = showParen (p > fixity) $+    showsPrec f1 e1 . (' ':) . (getInfName fx++) . (' ':) . +    showsPrec f2 e2 where+      fixity = snd $ lookupFix fx+      (f1, f2) = case fst $ lookupFix fx of+        AssocRight -> (fixity+1, fixity + infixSafe e2 AssocLeft fixity)+        AssocLeft  -> (fixity + infixSafe e1 AssocRight fixity, fixity+1)+        AssocNone  -> (fixity+1, fixity+1)++      -- This is a little bit awkward, but at least seems to produce no false+      -- results anymore+      infixSafe :: SExpr -> Assoc -> Int -> Int+      infixSafe (SInfix fx'' _ _) assoc fx'+        | lookupFix fx'' == (assoc, fx') = 1+        | otherwise = 0+      infixSafe _ _ _ = 0 -- doesn't matter++prettyPrecPattern :: Int -> Pattern -> ShowS+prettyPrecPattern _ (PVar v) = showString v+prettyPrecPattern _ (PTuple p1 p2) = showParen True $+  prettyPrecPattern 0 p1 . (", "++) . prettyPrecPattern 0 p2+prettyPrecPattern p (PCons p1 p2) = showParen (p>5) $+  prettyPrecPattern 6 p1 . (':':) . prettyPrecPattern 5 p2+  +isOperator :: String -> Bool+isOperator s = s /= "()" && all (\c -> isSymbol c || isPunctuation c) s++getInfName :: String -> String+getInfName str = if isOperator str then str else "`"++str++"`"++getPrefName :: String -> String+getPrefName str = if isOperator str || ',' `elem` str then "("++str++")" else str++{-+instance Show Assoc where+  show AssocLeft  = "AssocLeft"+  show AssocRight = "AssocRight"+  show AssocNone  = "AssocNone"++instance Ord Assoc where+  AssocNone <= _ = True+  _ <= AssocNone = False+  AssocLeft <= _ = True+  _ <= AssocLeft = False+  _ <= _ = True+-}
+ library/Plugin/Pl/Rules.hs view
@@ -0,0 +1,761 @@+{-# LANGUAGE ExistentialQuantification #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE ScopedTypeVariables #-}+--+-- | This marvellous module contributed by Thomas J\344ger+--+module Plugin.Pl.Rules (RewriteRule(..), rules, fire) where++import Plugin.Pl.Common++import Data.Array+import qualified Data.Set as S++import Control.Monad.Fix (fix)++--import PlModule.PrettyPrinter++-- Next time I do somthing like this, I'll actually think about the combinator+-- language before, instead of producing something ad-hoc like this:+data RewriteRule +  = RR Rewrite Rewrite+  | CRR (Expr -> Maybe Expr)+  | Down RewriteRule RewriteRule+  | Up RewriteRule RewriteRule+  | Or [RewriteRule]+  | OrElse RewriteRule RewriteRule+  | Then RewriteRule RewriteRule+  | Opt RewriteRule+  | If RewriteRule RewriteRule+  | Hard RewriteRule++-- No MLambda here because we only consider closed Terms (no alpha-renaming!).+data MExpr+  = MApp !MExpr !MExpr+  | Hole !Int+  | Quote !Expr+  deriving Eq++--instance Show MExpr where+--  show = show . fromMExpr++data Rewrite = Rewrite {+  holes :: MExpr,+  rid :: Int -- rlength - 1+} --deriving Show++-- What are you gonna do when no recursive modules are possible?+class RewriteC a where+  getRewrite :: a -> Rewrite ++instance RewriteC MExpr where+  getRewrite rule = Rewrite {+    holes   = rule,+    rid = 0+  }++type ExprArr = Array Int Expr++myFire :: ExprArr -> MExpr -> MExpr+myFire xs (MApp e1 e2) = MApp (myFire xs e1) (myFire xs e2)+myFire xs (Hole h) = Quote $ xs ! h+myFire _ me = me++nub' :: Ord a => [a] -> [a]+nub' = S.toList . S.fromList++uniqueArray :: Ord v => Int -> [(Int, v)] -> Maybe (Array Int v)+uniqueArray n lst +  | length (nub' lst) == n = Just $ array (0,n-1) lst+  | otherwise = Nothing              ++match :: Rewrite -> Expr -> Maybe ExprArr+match (Rewrite hl rid') e  = uniqueArray rid' =<< matchWith hl e++fire' :: Rewrite -> ExprArr -> MExpr+fire' (Rewrite hl _)   = (`myFire` hl)++fire :: Rewrite -> Rewrite -> Expr -> Maybe Expr+fire r1 r2 e = (fromMExpr . fire' r2) `fmap` match r1 e++matchWith :: MExpr -> Expr -> Maybe [(Int, Expr)]+matchWith (MApp e1 e2) (App e1' e2') = +  liftM2 (++) (matchWith e1 e1') (matchWith e2 e2')+matchWith (Quote e) e' = if e == e' then Just [] else Nothing+matchWith (Hole k) e = Just [(k,e)]+matchWith _ _ = Nothing++fromMExpr :: MExpr -> Expr+fromMExpr (MApp e1 e2)  = App (fromMExpr e1) (fromMExpr e2)+fromMExpr (Hole _)      = Var Pref "Hole" -- error "Hole in MExpr"+fromMExpr (Quote e)     = e++instance RewriteC a => RewriteC (MExpr -> a) where+  getRewrite rule = Rewrite {+    holes = holes . getRewrite . rule . Hole $ pid,+    rid   = pid + 1+  } where +    pid = rid $ getRewrite (bt :: a)++-- Yet another pointless transformation+transformM :: Int -> MExpr -> MExpr+transformM _ (Quote e) = constE `a` Quote e+transformM n (Hole n') = if n == n' then idE else constE `a` Hole n'+transformM n (Quote (Var _ ".") `MApp` e1 `MApp` e2)+  | e1 `hasHole` n && not (e2 `hasHole` n) +  = flipE `a` compE `a` e2 `c` transformM n e1+transformM n e@(MApp e1 e2) +  | fr1 && fr2 = sE `a` transformM n e1 `a` transformM n e2+  | fr1        = flipE `a` transformM n e1 `a` e2+  | fr2, Hole n' <- e2, n' == n = e1+  | fr2        = e1 `c` transformM n e2+  | otherwise  = constE `a` e+  where+    fr1 = e1 `hasHole` n+    fr2 = e2 `hasHole` n++hasHole :: MExpr -> Int -> Bool+hasHole (MApp e1 e2) n = e1 `hasHole` n || e2 `hasHole` n+hasHole (Quote _)   _ = False+hasHole (Hole n')   n = n == n'++--+-- haddock doesn't like n+k patterns, so rewrite them+--+getVariants, getVariants' :: Rewrite -> [Rewrite]+getVariants' r@(Rewrite _ 0)  = [r]+getVariants' r@(Rewrite e nk)+    | nk >= 1    = r : getVariants (Rewrite e' (nk-1))+    | otherwise  = error "getVariants' : nk went negative"+    where+        e' = decHoles $ transformM 0 e++        decHoles (Hole n')    = Hole (n'-1)+        decHoles (MApp e1 e2) = decHoles e1 `MApp` decHoles e2+        decHoles me           = me++getVariants = getVariants' -- r = trace (show vs) vs where vs = getVariants' r++rr, rr0, rr1, rr2 :: RewriteC a => a -> a -> RewriteRule+-- use this rewrite rule and rewrite rules derived from it by iterated+-- pointless transformation+rrList :: RewriteC a => a -> a -> [RewriteRule]+rrList r1 r2 = zipWith RR (getVariants r1') (getVariants r2') where+  r1' = getRewrite r1+  r2' = getRewrite r2++rr  r1 r2 = Or          $ rrList r1 r2+rr1 r1 r2 = Or . take 2 $ rrList r1 r2+rr2 r1 r2 = Or . take 3 $ rrList r1 r2++-- use only this rewrite rule+rr0 r1 r2 = RR r1' r2' where+  r1' = getRewrite r1+  r2' = getRewrite r2+  +down, up :: RewriteRule -> RewriteRule+down = fix . Down+up   = fix . Up+++idE, flipE, bindE, extE, returnE, consE, appendE, nilE, foldrE, foldlE, fstE,+  sndE, dollarE, constE, uncurryE, curryE, compE, headE, tailE, sE, commaE, +  fixE, foldl1E, notE, equalsE, nequalsE, plusE, multE, zeroE, oneE, lengthE, +  sumE, productE, concatE, concatMapE, joinE, mapE, fmapE, fmapIE, subtractE, +  minusE, liftME, apE, liftM2E, seqME, zipE, zipWithE, +  crossE, firstE, secondE, andE, orE, allE, anyE :: MExpr+idE        = Quote $ Var Pref "id"+flipE      = Quote $ Var Pref "flip"+constE     = Quote $ Var Pref "const"+compE      = Quote $ Var Inf "."+sE         = Quote $ Var Pref "ap"+fixE       = Quote $ Var Pref "fix"+bindE      = Quote $ Var Inf  ">>="+extE       = Quote $ Var Inf  "=<<"+returnE    = Quote $ Var Pref "return"+consE      = Quote $ Var Inf  ":"+nilE       = Quote $ Var Pref "[]"+appendE    = Quote $ Var Inf  "++"+foldrE     = Quote $ Var Pref "foldr"+foldlE     = Quote $ Var Pref "foldl"+fstE       = Quote $ Var Pref "fst"+sndE       = Quote $ Var Pref "snd"+dollarE    = Quote $ Var Inf  "$"+uncurryE   = Quote $ Var Pref "uncurry"+curryE     = Quote $ Var Pref "curry"+headE      = Quote $ Var Pref "head"+tailE      = Quote $ Var Pref "tail"+commaE     = Quote $ Var Inf  ","+foldl1E    = Quote $ Var Pref "foldl1"+equalsE    = Quote $ Var Inf  "=="+nequalsE   = Quote $ Var Inf  "/="+notE       = Quote $ Var Pref "not"+plusE      = Quote $ Var Inf  "+"+multE      = Quote $ Var Inf  "*"+zeroE      = Quote $ Var Pref "0"+oneE       = Quote $ Var Pref "1"+lengthE    = Quote $ Var Pref "length"+sumE       = Quote $ Var Pref "sum"+productE   = Quote $ Var Pref "product"+concatE    = Quote $ Var Pref "concat"+concatMapE = Quote $ Var Pref "concatMap"+joinE      = Quote $ Var Pref "join"+mapE       = Quote $ Var Pref "map"+fmapE      = Quote $ Var Pref "fmap"+fmapIE     = Quote $ Var Inf  "fmap"+subtractE  = Quote $ Var Pref "subtract"+minusE     = Quote $ Var Inf  "-"+liftME     = Quote $ Var Pref "liftM"+liftM2E    = Quote $ Var Pref "liftM2"+apE        = Quote $ Var Inf  "ap"+seqME      = Quote $ Var Inf  ">>"+zipE       = Quote $ Var Pref "zip"+zipWithE   = Quote $ Var Pref "zipWith"+crossE     = Quote $ Var Inf  "***"+firstE     = Quote $ Var Pref "first"+secondE    = Quote $ Var Pref "second"+andE       = Quote $ Var Pref "and"+orE        = Quote $ Var Pref "or"+allE       = Quote $ Var Pref "all"+anyE       = Quote $ Var Pref "any"++++a, c :: MExpr -> MExpr -> MExpr+a       = MApp+c e1 e2 = compE `a` e1 `a` e2+infixl 9 `a`+infixr 8 `c`+++collapseLists :: Expr -> Maybe Expr+collapseLists (Var _ "++" `App` e1 `App` e2)+  | (xs,x) <- getList e1, x==nil,+    (ys,y) <- getList e2, y==nil = Just $ makeList $ xs ++ ys+collapseLists _ = Nothing++data Binary = forall a b c. (Read a, Show a, Read b, Show b, Read c, Show c) => BA (a -> b -> c)++evalBinary :: [(String, Binary)] -> Expr -> Maybe Expr+evalBinary fs (Var _ f' `App` Var _ x' `App` Var _ y')+  | Just (BA f) <- lookup f' fs = (Var Pref . show) `fmap` liftM2 f (readM x') (readM y')+evalBinary _ _ = Nothing++data Unary = forall a b. (Read a, Show a, Read b, Show b) => UA (a -> b)++evalUnary :: [(String, Unary)] -> Expr -> Maybe Expr+evalUnary fs (Var _ f' `App` Var _ x')+  | Just (UA f) <- lookup f' fs = (Var Pref . show . f) `fmap` readM x'+evalUnary _ _ = Nothing++assocR, assocL, assoc :: [String] -> Expr -> Maybe Expr+-- (f `op` g) `op` h --> f `op` (g `op` h)+assocR ops (Var f1 op1 `App` (Var f2 op2 `App` e1 `App` e2) `App` e3)+  | op1 == op2 && op1 `elem` ops +  = Just (Var f1 op1 `App` e1 `App` (Var f2 op2 `App` e2 `App` e3))+assocR _ _ = Nothing++-- f `op` (g `op` h) --> (f `op` g) `op` h+assocL ops (Var f1 op1 `App` e1 `App` (Var f2 op2 `App` e2 `App` e3))+  | op1 == op2 && op1 `elem` ops +  = Just (Var f1 op1 `App` (Var f2 op2 `App` e1 `App` e2) `App` e3)+assocL _ _ = Nothing++-- op f . op g --> op (f `op` g)+assoc ops (Var _ "." `App` (Var f1 op1 `App` e1) `App` (Var f2 op2 `App` e2))+  | op1 == op2 && op1 `elem` ops+  = Just (Var f1 op1 `App` (Var f2 op2 `App` e1 `App` e2))+assoc _ _ = Nothing++commutative :: [String] -> Expr -> Maybe Expr+commutative ops (Var f op `App` e1 `App` e2) +  | op `elem` ops = Just (Var f op `App` e2 `App` e1)+commutative ops (Var _ "flip" `App` e@(Var _ op)) | op `elem` ops = Just e+commutative _ _ = Nothing++-- TODO: Move rules into a file.+{-# INLINE simplifies #-}+simplifies :: RewriteRule+simplifies = Or [+  -- (f . g) x --> f (g x)+  rr0 (\f g x -> (f `c` g) `a` x)+      (\f g x -> f `a` (g `a` x)),+  -- id x --> x+  rr0 (\x -> idE `a` x)+      (\x -> x),+  -- flip (flip x) --> x+  rr  (\x -> flipE `a` (flipE `a` x))+      (\x -> x),+  -- flip id x . f --> flip f x+  rr0 (\f x -> (flipE `a` idE `a` x) `c` f)+      (\f x -> flipE `a` f `a` x),+  -- id . f --> f+  rr0 (\f -> idE `c` f)+      (\f -> f),+  -- f . id --> f+  rr0 (\f -> f `c` idE)+      (\f -> f),+  -- const x y --> x+  rr0 (\x y -> constE `a` x `a` y)+      (\x _ -> x),+  -- not (not x) --> x+  rr  (\x -> notE `a` (notE `a` x))+      (\x -> x),+  -- fst (x,y) --> x+  rr  (\x y -> fstE `a` (commaE `a` x `a` y))+      (\x _ -> x),+  -- snd (x,y) --> y+  rr  (\x y -> sndE `a` (commaE `a` x `a` y))+      (\_ y -> y),+  -- head (x:xs) --> x+  rr  (\x xs -> headE `a` (consE `a` x `a` xs))+      (\x _  -> x),+  -- tail (x:xs) --> xs+  rr  (\x xs -> tailE `a` (consE `a` x `a` xs))+      (\_ xs -> xs),+  -- uncurry f (x,y) --> f x y+  rr1 (\f x y -> uncurryE `a` f `a` (commaE `a` x `a` y))+      (\f x y -> f `a` x `a` y),+  -- uncurry (,) --> id+  rr  (uncurryE `a` commaE)+      (idE),+  -- uncurry f . s (,) g --> s f g+  rr1 (\f g -> (uncurryE `a` f) `c` (sE `a` commaE `a` g))+      (\f g -> sE `a` f `a` g),+  -- curry fst --> const+  rr (curryE `a` fstE) (constE),+  -- curry snd --> const id+  rr (curryE `a` sndE) (constE `a` idE),+  -- s f g x --> f x (g x)+  rr0 (\f g x -> sE `a` f `a` g `a` x)+      (\f g x -> f `a` x `a` (g `a` x)),+  -- flip f x y --> f y x+  rr0 (\f x y -> flipE `a` f `a` x `a` y)+      (\f x y -> f `a` y `a` x),+  -- flip (=<<) --> (>>=)+  rr0 (flipE `a` extE)+      bindE,++  -- TODO: Think about map/fmap+  -- fmap id --> id+  rr (fmapE `a` idE)+     (idE),+  -- map id --> id+  rr (mapE `a` idE)+     (idE),+  -- (f . g) . h --> f . (g . h)+  rr0 (\f g h -> (f `c` g) `c` h)+      (\f g h -> f `c` (g `c` h)),+  -- fmap f . fmap g -> fmap (f . g)+  rr0 (\f g -> fmapE `a` f `c` fmapE `a` g)+      (\f g -> fmapE `a` (f `c` g)),+  -- map f . map g -> map (f . g)+  rr0 (\f g -> mapE `a` f `c` mapE `a` g)+      (\f g -> mapE `a` (f `c` g))+  +  ]++onceRewrites :: RewriteRule+onceRewrites = Hard $ Or [+  -- ($) --> id+  rr0 (dollarE)+      idE,+  -- concatMap --> (=<<)+  rr concatMapE extE,+  -- concat    --> join+  rr concatE joinE,+  -- liftM --> fmap+  rr liftME fmapE,+  -- map --> fmap+  rr mapE fmapE,+  -- subtract -> flip (-)+  rr  subtractE+      (flipE `a` minusE)+  ]++-- Now we can state rewrite rules in a nice high level way+-- Rewrite rules should be as pointful as possible since the pointless variants+-- will be derived automatically.+rules :: RewriteRule+rules = Or [+  -- f (g x) --> (f . g) x+  Hard $+  rr  (\f g x -> f `a` (g `a` x)) +      (\f g x -> (f `c` g) `a` x),+  -- (>>=) --> flip (=<<)+  Hard $+  rr  bindE+      (flipE `a` extE),+  -- (.) id --> id+  rr (compE `a` idE)+     idE,+  -- (++) [x] --> (:) x+  rr  (\x -> appendE `a` (consE `a` x `a` nilE))+      (\x -> consE `a` x),+  -- (=<<) return --> id+  rr  (extE `a` returnE)+      idE,+  -- (=<<) f (return x) -> f x+  rr  (\f x -> extE `a` f `a` (returnE `a` x))+      (\f x -> f `a` x),+  -- (=<<) ((=<<) f . g) --> (=<<) f . (=<<) g+  rr  (\f g -> extE `a` ((extE `a` f) `c` g))+      (\f g -> (extE `a` f) `c` (extE `a` g)),+  -- flip (f . g) --> flip (.) g . flip f+  Hard $+  rr  (\f g -> flipE `a` (f `c` g))+      (\f g -> (flipE `a` compE `a` g) `c` (flipE `a` f)),+  -- flip (.) f . flip id --> flip f +  rr  (\f -> (flipE `a` compE `a` f) `c` (flipE `a` idE))+      (\f -> flipE `a` f),+  -- flip (.) f . flip flip --> flip (flip . f)+  rr  (\f -> (flipE `a` compE `a` f) `c` (flipE `a` flipE))+      (\f -> flipE `a` (flipE `c` f)),+  -- flip (flip (flip . f) g) --> flip (flip . flip f) g+  rr1 (\f g -> flipE `a` (flipE `a` (flipE `c` f) `a` g))+      (\f g -> flipE `a` (flipE `c` flipE `a` f) `a` g),+  +  -- flip (.) id --> id+  rr (flipE `a` compE `a` idE)+     idE,+  -- (.) . flip id --> flip flip+  rr  (compE `c` (flipE `a` idE))+      (flipE `a` flipE),+  -- s const x y --> y+  rr  (\x y -> sE `a` constE `a` x `a` y)+      (\_ y -> y),+  -- s (const . f) g --> f+  rr1 (\f g -> sE `a` (constE `c` f) `a` g)+      (\f _ -> f),+  -- s (const f) --> (.) f+  rr  (\f -> sE `a` (constE `a` f))+      (\f -> compE `a` f),+  -- s (f . fst) snd --> uncurry f+  rr  (\f -> sE `a` (f `c` fstE) `a` sndE)+      (\f -> uncurryE `a` f),+  -- fst (join (,) x) --> x+  rr (\x -> fstE `a` (joinE `a` commaE `a` x))+     (\x -> x),+  -- snd (join (,) x) --> x+  rr (\x -> sndE `a` (joinE `a` commaE `a` x))+     (\x -> x),+  -- The next two are `simplifies', strictly speaking, but invoked rarely.+  -- uncurry f (x,y) --> f x y+--  rr  (\f x y -> uncurryE `a` f `a` (commaE `a` x `a` y))+--      (\f x y -> f `a` x `a` y),+  -- curry (uncurry f) --> f+  rr (\f -> curryE `a` (uncurryE `a` f))+     (\f -> f),+  -- uncurry (curry f) --> f+  rr (\f -> uncurryE `a` (curryE `a` f))+     (\f -> f),+  -- (const id . f) --> const id+  rr  (\f -> (constE `a` idE) `c` f)+      (\_ -> constE `a` idE),+  -- const x . f --> const x+  rr (\x f -> constE `a` x `c` f)+     (\x _ -> constE `a` x),+  -- fix f --> f (fix x)+  Hard $+  rr0 (\f -> fixE `a` f)+      (\f -> f `a` (fixE `a` f)),+  -- f (fix f) --> fix x+  Hard $+  rr0 (\f -> f `a` (fixE `a` f))+      (\f -> fixE `a` f),+  -- fix f --> f (f (fix x))+  Hard $ +  rr0 (\f -> fixE `a` f)+      (\f -> f `a` (f `a` (fixE `a` f))),+  -- fix (const f) --> f+  rr (\f -> fixE `a` (constE `a` f)) +     (\f -> f),+  -- flip const x --> id+  rr  (\x -> flipE `a` constE `a` x)+      (\_ -> idE),+  -- const . f --> flip (const f)+  Hard $ +  rr  (\f -> constE `c` f)+      (\f -> flipE `a` (constE `a` f)),+  -- not (x == y) -> x /= y+  rr2 (\x y -> notE `a` (equalsE `a` x `a` y))+      (\x y -> nequalsE `a` x `a` y),+  -- not (x /= y) -> x == y+  rr2 (\x y -> notE `a` (nequalsE `a` x `a` y))+      (\x y -> equalsE `a` x `a` y),+  If (Or [rr plusE plusE, rr minusE minusE, rr multE multE]) $ down $ Or [+    -- 0 + x --> x+    rr  (\x -> plusE `a` zeroE `a` x)+        (\x -> x),+    -- 0 * x --> 0+    rr  (\x -> multE `a` zeroE `a` x)+        (\_ -> zeroE),+    -- 1 * x --> x+    rr  (\x -> multE `a` oneE `a` x)+        (\x -> x),+    -- x - x --> 0+    rr  (\x -> minusE `a` x `a` x)+        (\_ -> zeroE),+    -- x - y + y --> x+    rr  (\y x -> plusE `a` (minusE `a` x `a` y) `a` y)+        (\_ x -> x),+    -- x + y - y --> x+    rr  (\y x -> minusE `a` (plusE `a` x `a` y) `a` y)+        (\_ x -> x),+    -- x + (y - z) --> x + y - z+    rr  (\x y z -> plusE `a` x `a` (minusE `a` y `a` z))+        (\x y z -> minusE `a` (plusE `a` x `a` y) `a` z),+    -- x - (y + z) --> x - y - z+    rr  (\x y z -> minusE `a` x `a` (plusE `a` y `a` z))+        (\x y z -> minusE `a` (minusE `a` x `a` y) `a` z),+    -- x - (y - z) --> x + y - z+    rr  (\x y z -> minusE `a` x `a` (minusE `a` y `a` z))+        (\x y z -> minusE `a` (plusE `a` x `a` y) `a` z)+  ],++  Hard onceRewrites,+  -- join (fmap f x) --> f =<< x+  rr (\f x -> joinE `a` (fmapE `a` f `a` x))+     (\f x -> extE `a` f `a` x),+  -- (=<<) id --> join+  rr (extE `a` idE) joinE,+  -- join --> (=<<) id+  Hard $+  rr joinE (extE `a` idE),+  -- join (return x) --> x+  rr (\x -> joinE `a` (returnE `a` x))+     (\x -> x),+  -- (return . f) =<< m --> fmap f m+  rr (\f m -> extE `a` (returnE `c` f) `a` m)+     (\f m -> fmapIE `a` f `a` m),+  -- (x >>=) . (return .) . f  --> flip (fmap . f) x+  rr (\f x -> bindE `a` x `c` (compE `a` returnE) `c` f)+     (\f x -> flipE `a` (fmapIE `c` f) `a` x),+  -- (>>=) (return f) --> flip id f+  rr (\f -> bindE `a` (returnE `a` f))+     (\f -> flipE `a` idE `a` f),+  -- liftM2 f x --> ap (f `fmap` x)+  Hard $+  rr (\f x -> liftM2E `a` f `a` x)+     (\f x -> apE `a` (fmapIE `a` f `a` x)),+  -- liftM2 f (return x) --> fmap (f x)+  rr (\f x -> liftM2E `a` f `a` (returnE `a` x))+     (\f x -> fmapIE `a` (f `a` x)),+  -- f `fmap` return x --> return (f x)+  rr (\f x -> fmapE `a` f `a` (returnE `a` x))+     (\f x -> returnE `a` (f `a` x)),+  -- (=<<) . flip (fmap . f) --> flip liftM2 f+  Hard $+  rr (\f -> extE `c` flipE `a` (fmapE `c` f))+     (\f -> flipE `a` liftM2E `a` f),+  +  -- (.) -> fmap+  Hard $ +  rr compE fmapE,++  -- map f (zip xs ys) --> zipWith (curry f) xs ys+  Hard $+  rr (\f xs ys -> mapE `a` f `a` (zipE `a` xs `a` ys))+     (\f xs ys -> zipWithE `a` (curryE `a` f) `a` xs `a` ys),+  -- zipWith (,) --> zip (,)+  rr (zipWithE `a` commaE) zipE,++  -- all f --> and . map f+  Hard $+  rr (\f -> allE `a` f)+     (\f -> andE `c` mapE `a` f),+  -- and . map f --> all f+  rr (\f -> andE `c` mapE `a` f)+     (\f -> allE `a` f),+  -- any f --> or . map f+  Hard $+  rr (\f -> anyE `a` f)+     (\f -> orE `c` mapE `a` f),+  -- or . map f --> any f+  rr (\f -> orE `c` mapE `a` f)+     (\f -> anyE `a` f),++  -- return f `ap` x --> fmap f x+  rr (\f x -> apE `a` (returnE `a` f) `a` x)+     (\f x -> fmapIE `a` f `a` x),+  -- ap (f `fmap` x) --> liftM2 f x+  rr (\f x -> apE `a` (fmapIE `a` f `a` x))+     (\f x -> liftM2E `a` f `a` x),+  -- f `ap` x --> (`fmap` x) =<< f+  Hard $+  rr (\f x -> apE `a` f `a` x)+     (\f x -> extE `a` (flipE `a` fmapIE `a` x) `a` f),+  -- (`fmap` x) =<< f --> f `ap` x+  rr (\f x -> extE `a` (flipE `a` fmapIE `a` x) `a` f)+     (\f x -> apE `a` f `a` x),+  -- (x >>=) . flip (fmap . f) -> liftM2 f x+  rr (\f x -> bindE `a` x `c` flipE `a` (fmapE `c` f))+     (\f x -> liftM2E `a` f `a` x),++  -- (f =<< m) x --> f (m x) x+  rr0 (\f m x -> extE `a` f `a` m `a` x)+      (\f m x -> f `a` (m `a` x) `a` x),+  -- (fmap f g x) --> f (g x)+  rr0 (\f g x -> fmapE `a` f `a` g `a` x)+      (\f g x -> f `a` (g `a` x)),+  -- return x y --> y+  rr  (\y x -> returnE `a` x `a` y)+      (\y _ -> y),+  -- liftM2 f g h x --> g x `h` h x+  rr0 (\f g h x -> liftM2E `a` f `a` g `a` h `a` x)+      (\f g h x -> f `a` (g `a` x) `a` (h `a` x)),+  -- ap f id --> join f+  rr  (\f -> apE `a` f `a` idE)+      (\f -> joinE `a` f),++  -- (=<<) const q --> flip (>>) q+  Hard $ -- ??+  rr (\q p -> extE `a` (constE `a` q) `a` p)+     (\q p -> seqME `a` p `a` q),+  -- p >> q --> const q =<< p+  Hard $+  rr (\p q -> seqME `a` p `a` q)+     (\p q -> extE `a` (constE `a` q) `a` p),++  -- experimental support for Control.Arrow stuff +  -- (costs quite a bit of performace)+  -- uncurry ((. g) . (,) . f) --> f *** g+  rr (\f g -> uncurryE `a` ((flipE `a` compE `a` g) `c` commaE `c` f))+     (\f g -> crossE `a` f `a` g),+  -- uncurry ((,) . f) --> first f+  rr (\f -> uncurryE `a` (commaE `c` f))+     (\f -> firstE `a` f),+  -- uncurry ((. g) . (,)) --> second g+  rr (\g -> uncurryE `a` ((flipE `a` compE `a` g) `c` commaE))+     (\g -> secondE `a` g),+  -- I think we need all three of them:+  -- uncurry (const f) --> f . snd+  rr (\f -> uncurryE `a` (constE `a` f))+     (\f -> f `c` sndE),+  -- uncurry const --> fst+  rr (uncurryE `a` constE)+     (fstE),+  -- uncurry (const . f) --> f . fst+  rr (\f -> uncurryE `a` (constE `c` f))+     (\f -> f `c` fstE),++  -- TODO is this the right place?+  -- [x] --> return x+  Hard $+  rr (\x -> consE `a` x `a` nilE)+     (\x -> returnE `a` x),+  -- list destructors+  Hard $ +  If (Or [rr consE consE, rr nilE nilE]) $ Or [+    down $ Or [+      -- length [] --> 0+      rr (lengthE `a` nilE)+         zeroE,+      -- length (x:xs) --> 1 + length xs+      rr (\x xs -> lengthE `a` (consE `a` x `a` xs))+         (\_ xs -> plusE `a` oneE `a` (lengthE `a` xs))+    ],+    -- map/fmap elimination+    down $ Or [+      -- map f (x:xs) --> f x: map f xs+      rr (\f x xs -> mapE `a` f `a` (consE `a` x `a` xs))+         (\f x xs -> consE `a` (f `a` x) `a` (mapE `a` f `a` xs)),+      -- fmap f (x:xs) --> f x: Fmap f xs+      rr (\f x xs -> fmapE `a` f `a` (consE `a` x `a` xs))+         (\f x xs -> consE `a` (f `a` x) `a` (fmapE `a` f `a` xs)),+      -- map f []     --> []+      rr (\f -> mapE `a` f `a` nilE)+         (\_ -> nilE),+      -- fmap f []     --> []+      rr (\f -> fmapE `a` f `a` nilE)+         (\_ -> nilE)+    ],+    -- foldr elimination+    down $ Or [+      -- foldr f z (x:xs) --> f x (foldr f z xs)+      rr (\f x xs z -> (foldrE `a` f `a` z) `a` (consE `a` x `a` xs))+         (\f x xs z -> (f `a` x) `a` (foldrE `a` f `a` z `a` xs)),+      -- foldr f z [] --> z+      rr (\f z -> foldrE `a` f `a` z `a` nilE)+         (\_ z -> z)+    ],+    -- foldl elimination+    down $ Opt (CRR $ assocL ["."]) `Then` Or [+      -- sum xs --> foldl (+) 0 xs+      rr (\xs -> sumE `a` xs)+         (\xs -> foldlE `a` plusE `a` zeroE `a` xs),+      -- product xs --> foldl (*) 1 xs+      rr (\xs -> productE `a` xs)+         (\xs -> foldlE `a` multE `a` oneE `a` xs),+      -- foldl1 f (x:xs) --> foldl f x xs+      rr (\f x xs -> foldl1E `a` f `a` (consE `a` x `a` xs))+         (\f x xs -> foldlE `a` f `a` x `a` xs),+      -- foldl f z (x:xs) --> foldl f (f z x) xs+      rr (\f z x xs -> (foldlE `a` f `a` z) `a` (consE `a` x `a` xs))+         (\f z x xs -> foldlE `a` f `a` (f `a` z `a` x) `a` xs),+      -- foldl f z [] --> z+      rr (\f z -> foldlE `a` f `a` z `a` nilE)+         (\_ z -> z),+      -- special rule:+      -- foldl f z [x] --> f z x+      rr (\f z x -> foldlE `a` f `a` z `a` (returnE `a` x))+         (\f z x -> f `a` z `a` x),+      rr (\f z x -> foldlE `a` f `a` z `a` (consE `a` x `a` nilE))+         (\f z x -> f `a` z `a` x)+    ] `OrElse` (+      -- (:) x --> (++) [x]+      Opt (rr0 (\x -> consE `a` x)+         (\x -> appendE `a` (consE `a` x `a` nilE))) `Then`+      -- More special rule: (:) x . (++) ys --> (++) (x:ys)+      up (rr0 (\x ys -> (consE `a` x) `c` (appendE `a` ys))+         (\x ys -> appendE `a` (consE `a` x `a` ys)))+      )+  ],++  -- Complicated Transformations+  CRR (collapseLists),+  up $ Or [CRR (evalUnary unaryBuiltins), CRR (evalBinary binaryBuiltins)],+  up $ CRR (assoc assocOps),+  up $ CRR (assocL assocOps),+  up $ CRR (assocR assocOps),+  Up (CRR (commutative commutativeOps)) $ down $ Or [CRR $ assocL assocLOps,+                                                     CRR $ assocR assocROps],++  Hard $ simplifies+  ] `Then` Opt (up simplifies)+assocLOps, assocROps, assocOps :: [String]+assocLOps = ["+", "*", "&&", "||", "max", "min"]+assocROps = [".", "++"]+assocOps  = assocLOps ++ assocROps++commutativeOps :: [String]+commutativeOps = ["*", "+", "==", "/=", "max", "min"]++unaryBuiltins :: [(String,Unary)]+unaryBuiltins = [+    ("not",    UA (not    :: Bool -> Bool)),+    ("negate", UA (negate :: Integer -> Integer)),+    ("signum", UA (signum :: Integer -> Integer)),+    ("abs",    UA (abs    :: Integer -> Integer))+  ]++binaryBuiltins :: [(String,Binary)]+binaryBuiltins = [+    ("+",    BA ((+)  :: Integer -> Integer -> Integer)),+    ("-",    BA ((-)  :: Integer -> Integer -> Integer)),+    ("*",    BA ((*)  :: Integer -> Integer -> Integer)),+    ("^",    BA ((^)  :: Integer -> Integer -> Integer)),+    ("<",    BA ((<)  :: Integer -> Integer -> Bool)),+    (">",    BA ((>)  :: Integer -> Integer -> Bool)),+    ("==",   BA ((==) :: Integer -> Integer -> Bool)),+    ("/=",   BA ((/=) :: Integer -> Integer -> Bool)),+    ("<=",   BA ((<=) :: Integer -> Integer -> Bool)),+    (">=",   BA ((>=) :: Integer -> Integer -> Bool)),+    ("div",  BA (div  :: Integer -> Integer -> Integer)),+    ("mod",  BA (mod  :: Integer -> Integer -> Integer)),+    ("max",  BA (max  :: Integer -> Integer -> Integer)),+    ("min",  BA (min  :: Integer -> Integer -> Integer)),+    ("&&",   BA ((&&) :: Bool -> Bool -> Bool)),+    ("||",   BA ((||) :: Bool -> Bool -> Bool))+  ]+
+ library/Plugin/Pl/Transform.hs view
@@ -0,0 +1,119 @@+{-# LANGUAGE FlexibleInstances #-}+module Plugin.Pl.Transform (+    transform,+  ) where++import Plugin.Pl.Common+import Plugin.Pl.PrettyPrinter ()++import qualified Data.Map as M++import Data.Graph (stronglyConnComp, flattenSCC, flattenSCCs)+import Control.Monad.Trans.State++{-+nub :: Ord a => [a] -> [a]+nub = nub' S.empty where+  nub' _ [] = []+  nub' set (x:xs)+    | x `S.member` set = nub' set xs+    | otherwise = x: nub' (x `S.insert` set) xs+-}++occursP :: String -> Pattern -> Bool+occursP v (PVar v') = v == v'+occursP v (PTuple p1 p2) = v `occursP` p1 || v `occursP` p2+occursP v (PCons  p1 p2) = v `occursP` p1 || v `occursP` p2++freeIn :: String -> Expr -> Int+freeIn v (Var _ v') = fromEnum $ v == v'+freeIn v (Lambda pat e) = if v `occursP` pat then 0 else freeIn v e+freeIn v (App e1 e2) = freeIn v e1 + freeIn v e2+freeIn v (Let ds e') = if v `elem` map declName ds then 0 +  else freeIn v e' + sum [freeIn v e | Define _ e <- ds]++isFreeIn :: String -> Expr -> Bool+isFreeIn v e = freeIn v e > 0++tuple :: [Expr] -> Expr+tuple es  = foldr1 (\x y -> Var Inf "," `App` x `App` y) es++tupleP :: [String] -> Pattern+tupleP vs = foldr1 PTuple $ PVar `map` vs++dependsOn :: [Decl] -> Decl -> [Decl]+dependsOn ds d = [d' | d' <- ds, declName d' `isFreeIn` declExpr d]+  +unLet :: Expr -> Expr+unLet (App e1 e2) = App (unLet e1) (unLet e2)+unLet (Let [] e) = unLet e+unLet (Let ds e) = unLet $+  (Lambda (tupleP $ declName `map` dsYes) (Let dsNo e)) `App`+    (fix' `App` (Lambda (tupleP $ declName `map` dsYes)+                        (tuple  $ declExpr `map` dsYes)))+    where+  comps = stronglyConnComp [(d',d',dependsOn ds d') | d' <- ds]+  dsYes = flattenSCC $ head comps+  dsNo = flattenSCCs $ tail comps+  +unLet (Lambda v e) = Lambda v (unLet e)+unLet (Var f x) = Var f x++type Env = M.Map String String++-- It's a pity we still need that for the pointless transformation.+-- Otherwise a newly created id/const/... could be bound by a lambda+-- e.g. transform' (\id x -> x) ==> transform' (\id -> id) ==> id+alphaRename :: Expr -> Expr+alphaRename e = alpha e `evalState` M.empty where+  alpha :: Expr -> State Env Expr+  alpha (Var f v) = do fm <- get; return $ Var f $ maybe v id (M.lookup v fm)+  alpha (App e1 e2) = liftM2 App (alpha e1) (alpha e2)+  alpha (Let _ _) = assert False bt+  alpha (Lambda v e') = inEnv $ liftM2 Lambda (alphaPat v) (alpha e')++  -- act like a reader monad+  inEnv :: State s a -> State s a+  inEnv f = gets $ evalState f++  alphaPat (PVar v) = do+    fm <- get+    let v' = "$" ++ show (M.size fm)+    put $ M.insert v v' fm+    return $ PVar v'+  alphaPat (PTuple p1 p2) = liftM2 PTuple (alphaPat p1) (alphaPat p2)+  alphaPat (PCons p1 p2) = liftM2 PCons (alphaPat p1) (alphaPat p2)+++transform :: Expr -> Expr+transform = transform' . alphaRename . unLet++transform' :: Expr -> Expr+transform' (Let {}) = assert False bt+transform' (Var f v) = Var f v+transform' (App e1 e2) = App (transform' e1) (transform' e2)+transform' (Lambda (PTuple p1 p2) e) +  = transform' $ Lambda (PVar "z") $ +      (Lambda p1 $ Lambda p2 $ e) `App` f `App` s where+    f = Var Pref "fst" `App` Var Pref "z"+    s = Var Pref "snd" `App` Var Pref "z"+transform' (Lambda (PCons p1 p2) e) +  = transform' $ Lambda (PVar "z") $ +      (Lambda p1 $ Lambda p2 $ e) `App` f `App` s where+    f = Var Pref "head" `App` Var Pref "z"+    s = Var Pref "tail" `App` Var Pref "z"+transform' (Lambda (PVar v) e) = transform' $ getRidOfV e where+  getRidOfV (Var f v') | v == v'   = id'+                       | otherwise = const' `App` Var f v'+  getRidOfV l@(Lambda pat _) = assert (not $ v `occursP` pat) $ +    getRidOfV $ transform' l+  getRidOfV (Let {}) = assert False bt+  getRidOfV e'@(App e1 e2) +    | fr1 && fr2 = scomb `App` getRidOfV e1 `App` getRidOfV e2+    | fr1 = flip' `App` getRidOfV e1 `App` e2+    | Var _ v' <- e2, v' == v = e1+    | fr2 = comp `App` e1 `App` getRidOfV e2+    | True = const' `App` e'+    where+      fr1 = v `isFreeIn` e1+      fr2 = v `isFreeIn` e2
+ library/Pointfree.hs view
@@ -0,0 +1,31 @@+module Pointfree where++import Plugin.Pl.Common (mapTopLevel, mapTopLevel')+import Plugin.Pl.Optimize (optimize)+import Plugin.Pl.Parser (parsePF)+import Plugin.Pl.PrettyPrinter (prettyTopLevel)+import Plugin.Pl.Transform (transform)++import Data.Maybe (listToMaybe)++{- |+  >>> pointfree "I'm not a valid Haskell expression!"+  []+  >>> pointfree "sum xs = foldr (+) 0 xs"+  ["sum = id (fix (const (foldr (+) 0)))","sum = fix (const (foldr (+) 0))","sum = foldr (+) 0"]+-}+pointfree :: String -> [String]+pointfree+  = either+    (const [])+    (map prettyTopLevel . mapTopLevel' optimize . mapTopLevel transform)+  . parsePF++{- |+  >>> pointfree' "I'm not a valid Haskell expression!"+  Nothing+  >>> pointfree' "sum xs = foldr (+) 0 xs"+  Just "sum = foldr (+) 0"+-}+pointfree' :: String -> Maybe String+pointfree' = listToMaybe . reverse . pointfree