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{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE EmptyCase #-}
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE TupleSections #-}
module AST.Pretty where
import Control.Monad (ap)
import Data.List (intersperse)
import Data.Functor.Const
import AST
data Val f env where
VTop :: Val f '[]
VPush :: f t -> Val f env -> Val f (t : env)
type SVal = Val (Const String)
valprj :: Val f env -> Idx env t -> f t
valprj (VPush x _) IZ = x
valprj (VPush _ env) (IS i) = valprj env i
valprj VTop i = case i of {}
newtype M a = M { runM :: Int -> (a, Int) }
deriving (Functor)
instance Applicative M where { pure x = M (\i -> (x, i)) ; (<*>) = ap }
instance Monad M where { M f >>= g = M (\i -> let (x, j) = f i in runM (g x) j) }
genId :: M Int
genId = M (\i -> (i, i + 1))
genName :: M String
genName = ('x' :) . show <$> genId
ppExpr :: SList STy env -> Expr x env t -> String
ppExpr senv e = fst (runM (mkVal senv >>= \val -> ppExpr' 0 val e) 1) ""
where
mkVal :: SList STy env -> M (SVal env)
mkVal SNil = return VTop
mkVal (SCons _ v) = do
val <- mkVal v
name <- genName
return (VPush (Const name) val)
ppExpr' :: Int -> SVal env -> Expr x env t -> M ShowS
ppExpr' d val = \case
EVar _ _ i -> return $ showString $ getConst $ valprj val i
etop@ELet{} -> do
let collect :: SVal env -> Expr x env t -> M ([(String, ShowS)], ShowS)
collect val' (ELet _ rhs body) = do
name <- genName
(binds, core) <- collect (VPush (Const name) val') body
rhs' <- ppExpr' 0 val' rhs
return ((name, rhs') : binds, core)
collect val' e = ([],) <$> ppExpr' 0 val' e
(binds, core) <- collect val etop
let (open, close) = case binds of
[_] -> ("{ ", " }")
_ -> ("", "")
return $ showParen (d > 0) $
showString ("let " ++ open)
. foldr (.) id (intersperse (showString " ; ")
(map (\(name, rhs) -> showString (name ++ " = ") . rhs) binds))
. showString (close ++ " in ")
. core
EPair _ a b -> do
a' <- ppExpr' 0 val a
b' <- ppExpr' 0 val b
return $ showString "(" . a' . showString ", " . b' . showString ")"
EFst _ e -> do
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $ showString "fst " . e'
ESnd _ e -> do
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $ showString "snd " . e'
ENil _ -> return $ showString "()"
EInl _ _ e -> do
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $ showString "inl " . e'
EInr _ _ e -> do
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $ showString "inr " . e'
ECase _ e a b -> do
e' <- ppExpr' 0 val e
name1 <- genName
a' <- ppExpr' 0 (VPush (Const name1) val) a
name2 <- genName
b' <- ppExpr' 0 (VPush (Const name2) val) b
return $ showParen (d > 0) $
showString "case " . e' . showString (" of { Inl " ++ name1 ++ " -> ") . a'
. showString (" ; Inr " ++ name2 ++ " -> ") . b' . showString " }"
EConst _ ty v -> return $ showString $ case ty of
STI32 -> show v ; STI64 -> show v ; STF32 -> show v ; STF64 -> show v ; STBool -> show v
EOp _ op (EPair _ a b)
| (Infix, ops) <- operator op -> do
a' <- ppExpr' 9 val a
b' <- ppExpr' 9 val b
return $ showParen (d > 8) $ a' . showString (" " ++ ops ++ " ") . b'
EOp _ op e -> do
e' <- ppExpr' 11 val e
let ops = case operator op of
(Infix, s) -> "(" ++ s ++ ")"
(Prefix, s) -> s
return $ showParen (d > 10) $ showString (ops ++ " ") . e'
EMOne venv i e -> do
let venvlen = length (unSList venv)
varname = 'v' : show (venvlen - idx2int i)
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $
showString ("one " ++ show varname ++ " ") . e'
EMScope e -> do
let venv = case typeOf e of STEVM v _ -> v
venvlen = length (unSList venv)
varname = 'v' : show venvlen
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $
showString ("scope " ++ show varname ++ " ") . e'
EMReturn _ e -> do
e' <- ppExpr' 11 val e
return $ showParen (d > 10) $ showString ("return ") . e'
EMBind a b -> do
a' <- ppExpr' 0 val a
name <- genName
b' <- ppExpr' 0 (VPush (Const name) val) b
return $ showParen (d > 10) $ a' . showString (" >>= \\" ++ name ++ " -> ") . b'
EError _ s -> return $ showParen (d > 10) $ showString ("error " ++ show s)
_ -> undefined
data Fixity = Prefix | Infix
deriving (Show)
operator :: SOp a t -> (Fixity, String)
operator OAdd{} = (Infix, "+")
operator OMul{} = (Infix, "*")
operator ONeg{} = (Prefix, "negate")
operator OLt{} = (Infix, "<")
operator OLe{} = (Infix, "<=")
operator OEq{} = (Infix, "==")
operator ONot = (Prefix, "not")
idx2int :: Idx env t -> Int
idx2int IZ = 0
idx2int (IS n) = 1 + idx2int n
|
