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gyehoek-hs/src/Gyehoek/CPS/Eval.hs
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2026-09-03 13:42:12 -06:00

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Haskell

{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE DeriveAnyClass #-}
module Gyehoek.CPS.Eval
( evalProgram
, module Gyehoek.CPS.Syntax
, evalExp
) where
import Gyehoek.CPS.Syntax hiding (Hob(..), Obj(..))
import Control.Lens
import Data.Maybe (fromMaybe)
import Text.Show.Functions ()
import qualified Data.HashMap.Strict as H
import Gyehoek.Prelude
import Debug.Pretty.Simple
import Gyehoek.Jalmot
import Control.Monad.Cont qualified as Cont
import Gyehoek.Sexp qualified as S
import GHC.Generics (Generically(..))
import Gyehoek.Sexp ((:-)(..))
data Env = MkEnv
{ store :: HashMap Name Obj
}
deriving stock (Show, Generic, Data, Eq)
deriving (Semigroup, Monoid)
via Generically Env
emptyEnv = MkEnv
{ store = mempty
}
data Obj
= ObjImm Imm
| ObjHob Hob
deriving stock (Show, Generic, Data, Eq)
-- | a heap object.
data Hob
= HobClosure { code :: Abs, env :: Env}
-- should a continuation have a label, or an Obj?
| HobPair Obj Obj
deriving stock (Show, Generic, Data, Eq)
instance S.DatumIso Obj where
datumIso = S.match
$ S.With (S.datumIso @Imm >>>)
$ S.With (S.datumIso @Hob >>>)
$ S.End
instance S.DatumIso Hob where
datumIso = S.match
$ S.With (closure >>>)
$ S.With (conspair >>>)
$ S.End
where
conspair = S.dottedList (S.el S.datumIso) S.datumIso
-- closures can be printed, but not parsed.
closure :: S.G (S.Datum :- t) (Env :- Abs :- t)
closure = S.Flip $ S.PartialIso
(\(_:-_:-t) -> S.Unreadable [i|\#<procedure>|] :- t)
(const . Left $ mempty)
err :: Jalmot :> es => Text -> Eff es a
err = throwError . VMError
eval1 :: Jalmot :> es => Env -> Exp -> Eff es Obj
eval1 g e = eval g e >>= \case
[r] -> pure r
rs -> err [i|expected one value, but got #{rs}|]
pure1 :: Applicative f => a -> f (List a)
pure1 = pure . (:[])
eval
:: Jalmot :> es
=> Env -> Exp
-> Eff es (List Obj)
eval g (ExpLetRec bs e) = eval g' e
where
g' = g <> foldMap
(\(f,ab) -> mempty & #store . at f ?~
ObjHob (HobClosure ab g'))
bs
eval g (Halt rs) = traverse (evalVal g) rs
eval g (ExpContinue k xs) = evalVal g k >>= \case
ObjImm (ImmLabel "halt") -> traverse (evalVal g) xs
eval g (ExpApply f xs ktail) = do
f' <- evalVal g f
xs' <- traverse (evalVal g) xs
ktail' <- evalKexp g ktail
case f' of
ObjHob (HobClosure {code,env}) -> eval env' e
where
MkAbs bxs bktail e = code
env' = env
& #store <>~ H.fromList (zip bxs xs')
& maybe id (\b -> #store . at b ?~ ktail') bktail
eval g e = err [i|unimplemented exp: #{S.encodeOrShow' @Text S.datumIso e}|]
evalKexp :: Jalmot :> es => Env -> Kexp -> Eff es Obj
evalKexp g = \case
KexpVar x -> var g x
KexpKappa kap -> _
evalVal
:: Jalmot :> es
=> Env -> Val
-> Eff es Obj
evalVal g (ValImm imm) = pure $ ObjImm imm
evalVal g (ValVar x) = var g x
var :: Jalmot :> es => Env -> Name -> Eff es Obj
var _ "halt" = pure . ObjImm . ImmLabel $ "halt"
var g x = case g ^. #store . at x of
Just o -> pure o
Nothing -> err [i|unbound var #{x}|]
evalExp :: Jalmot :> es => Exp -> Eff es (List Obj)
evalExp e = eval emptyEnv e
evalProgram :: Jalmot :> es => Program -> Eff es (List Obj)
evalProgram (MkProgram lam) = evalExp [cps|
(letrec ((start #{lam}))
(start halt))
|]
p :: Program
p = [cps|
(λ (ktail)
(continue ktail 123))
|]
e1 :: Exp
e1 = [cps|
(continue $halt 123)
|]