310 lines
8.5 KiB
Haskell
310 lines
8.5 KiB
Haskell
module Builtins where
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import Code
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( Builtin(..)
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, Cho(..)
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, Datum(..)
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, Dereferenced(..)
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, Heap(..)
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, Instr(..)
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, Interp(..)
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, InterpFn
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, InterpFn
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, derefHeap
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, heapStruct
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, newHeapVars
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)
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import qualified Compiler as Co
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import Control.Monad.IO.Class (liftIO)
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import Control.Monad.Trans.Class (lift)
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import Control.Monad.Trans.State.Lazy (get, gets, modify)
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import Data.Functor.Identity (runIdentity)
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import Data.List (intercalate)
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import qualified Data.Map as M
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import Data.Maybe (fromJust)
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import Env (PrlgEnv(..), findAtom, findStruct, prlgError)
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import qualified IR
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import Interpreter (backtrack)
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import qualified Operators as O
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import System.Console.Haskeline (getInputChar, outputStr, outputStrLn)
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bi = Builtin
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showTerm itos heap = runIdentity . heapStruct atom struct hrec heap
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where
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atom (Atom a) = pure $ itos M.! a
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atom (Number n) = pure (show n)
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atom VoidRef = pure "_"
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struct (Struct (IR.Id h _)) args =
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pure $ itos M.! h ++ "(" ++ intercalate "," args ++ ")"
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hrec (HeapRef hr) ref =
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pure $
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(if hr == ref
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then "_X"
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else "_Rec") ++
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show hr
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printLocals :: InterpFn
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printLocals = do
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scope <- gets (gvar . cur)
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heap <- gets (heap . cur)
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IR.StrTable _ _ itos <- gets strtable
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flip traverse (M.assocs scope) $ \(local, ref) ->
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lift . outputStrLn $
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"_Local" ++ show local ++ " = " ++ showTerm itos heap ref
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return Nothing
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promptRetry :: InterpFn
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promptRetry = do
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last <- gets (null . cho)
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if last
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then return Nothing
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else promptRetry'
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promptRetry' :: InterpFn
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promptRetry' = do
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x <- lift $ getInputChar "? "
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case x of
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Just ';' -> backtrack
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_ -> return Nothing
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withArgs :: [Int] -> ([Int] -> InterpFn) -> InterpFn
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withArgs as f = do
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scope <- gets (hvar . cur)
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if all (`M.member` scope) as
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then f $ map (scope M.!) as
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else prlgError "arguments not bound"
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write' :: InterpFn -> InterpFn
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write' c =
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withArgs [0] $ \[arg] -> do
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heap <- gets (heap . cur)
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IR.StrTable _ _ itos <- gets strtable
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lift . outputStr $ showTerm itos heap arg
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c --this now allows error fallthrough but we might like EitherT
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write = write' $ return Nothing
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nl :: InterpFn
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nl = do
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lift $ outputStrLn ""
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return Nothing
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writeln :: InterpFn
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writeln = write' nl
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assertFact :: InterpFn
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assertFact =
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withArgs [0] $ \[arg] -> do
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heap <- gets (heap . cur)
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case Co.compileGoal . Co.squashVars <$>
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Co.heapStructPrlgInt Nothing heap arg of
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Just (U (Struct s):head) -> do
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addClause s $ head ++ [NoGoal]
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return Nothing
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_ -> prlgError "assert fact failure"
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assertClause :: InterpFn
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assertClause =
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withArgs [0, 1] $ \args -> do
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scope <- gets (hvar . cur)
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heap <- gets (heap . cur)
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comma <- findAtom ","
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cut <- findAtom "!"
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case Co.squashVars . IR.CallI 0 <$>
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traverse (Co.heapStructPrlgInt Nothing heap) args of
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Just (IR.CallI 0 [hs, gs]) ->
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let (U (Struct s):cs) =
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Co.compileGoal hs ++ Co.seqGoals (Co.compileGoals comma cut gs)
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in do addClause s cs
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return Nothing
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_ -> prlgError "assert clause failure"
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retractall :: InterpFn
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retractall =
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withArgs [0] $ \[arg] -> do
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heap <- gets (heap . cur)
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case derefHeap heap arg of
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BoundRef _ (Atom a) -> dropProcedure (IR.Id {IR.arity = 0, IR.str = a})
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BoundRef _ (Struct id) -> dropProcedure id
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_ -> prlgError "retractall needs a struct"
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call :: InterpFn
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call =
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withArgs [0] $ \[arg] -> do
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heap@(Heap _ hmap) <- gets (heap . cur)
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let exec base struct arity = do
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cur <- gets cur
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modify $ \s ->
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s
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{ cur =
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cur
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{ gol =
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[Call, Goal, U struct] ++
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[U $ hmap M.! (base + i) | i <- [1 .. arity]] ++ gol cur
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}
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}
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return Nothing
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case derefHeap heap arg of
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BoundRef addr struct@(Struct IR.Id {IR.arity = arity}) ->
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exec addr struct arity
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BoundRef addr (Atom a) ->
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exec addr (Struct IR.Id {IR.arity = 0, IR.str = a}) 0
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_ -> prlgError "not callable"
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{- struct building -}
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struct :: InterpFn
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struct = do
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heap <- gets (heap . cur)
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scope <- gets (hvar . cur)
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case derefHeap heap <$> scope M.!? 0 of
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Just (BoundRef addr (Struct IR.Id {IR.arity = arity, IR.str = str})) ->
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structUnify arity str
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_ -> structAssemble
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heapListLength listAtom heap ref = go 0 ref ref (id, fromJust . step)
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where
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nil r
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| BoundRef _ str <- derefHeap heap r = str == Atom listAtom
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| otherwise = False
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step r
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| BoundRef addr (Struct IR.Id {IR.arity = 2, IR.str = listAtom'}) <-
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derefHeap heap r
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, listAtom == listAtom' = Just (addr + 2)
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| otherwise = Nothing
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go n fast slow (f1, f2)
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| nil fast = Just n
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| Just fast' <- step fast =
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if slow == fast'
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then Nothing
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else go (n + 1) fast' (f1 slow) (f2, f1)
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| otherwise = Nothing
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structAssemble :: InterpFn
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structAssemble = do
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heap <- gets (heap . cur)
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scope <- gets (hvar . cur)
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case derefHeap heap <$> scope M.!? 1 of
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Just (BoundRef addr (Atom str)) -> do
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listAtom <- findAtom "[]"
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case scope M.!? 2 >>= heapListLength listAtom heap of
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Just arity -> structUnify arity str
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_ -> prlgError "struct arity unknown"
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_ -> prlgError "struct id unknown"
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structUnify arity str = do
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cur <- gets cur
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let h = heap cur
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scope = hvar cur
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listAtom <- findAtom "[]"
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let hcode = map U $ maybe VoidRef HeapRef . (scope M.!?) <$> [0 .. 2]
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(h', pvars) = newHeapVars arity h
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structData =
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Struct IR.Id {IR.arity = arity, IR.str = str} : map HeapRef pvars
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paramsData =
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concatMap
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(\pv -> [Struct IR.Id {IR.arity = 2, IR.str = listAtom}, HeapRef pv])
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pvars ++
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[Atom listAtom]
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gcode = map U $ structData ++ [Atom str] ++ paramsData
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modify $ \s ->
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s {cur = cur {heap = h', gol = gcode ++ gol cur, hed = hcode ++ hed cur}}
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return Nothing
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{- operator management -}
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op :: InterpFn
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op = do
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heap <- gets (heap . cur)
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scope <- gets (hvar . cur)
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IR.StrTable _ _ itos <- gets strtable
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case sequence $ map (fmap (derefHeap heap) . (scope M.!?)) [0 .. 2] of
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Just [BoundRef _ (Number prio), BoundRef _ (Atom fixityAtom), BoundRef _ (Atom opatom)]
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| Just op <-
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(,) <$> itos M.!? opatom <*>
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(O.Op prio <$> ((itos M.!? fixityAtom) >>= O.fixity)) -> do
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modify $ \s -> s {ops = op : ops s}
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return Nothing
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_ -> prlgError "bad op spec"
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stashOps :: InterpFn
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stashOps = do
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currentOps <- gets ops
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modify $ \s -> s {opstash = currentOps : opstash s}
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return Nothing
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popOps :: InterpFn
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popOps = do
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currentOps <- gets opstash
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case currentOps of
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[] -> prlgError "no op stash to pop"
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(ops':opss) -> do
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modify $ \s -> s {ops = ops', opstash = opss}
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return Nothing
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{- adding the builtins -}
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addOp op = modify $ \s -> s {ops = op : ops s}
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addClause struct code =
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modify $ \s ->
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s {defs = M.alter (Just . maybe [code] (\hs -> code : hs)) struct $ defs s}
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addProcedure struct heads =
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modify $ \s -> s {defs = M.insert struct heads $ defs s}
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dropProcedure struct = do
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d <- gets defs
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if struct `M.member` d
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then do
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modify $ \s -> s {defs = M.delete struct d}
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return Nothing
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else prlgError "no such definition" -- this should backtrack?
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addProc n a c = do
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sym <- findStruct n a
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addProcedure sym c
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addBi n i b =
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addProc n i [[U (LocalRef $ r - 1) | r <- [1 .. i]] ++ [Invoke $ bi b]]
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addPrelude :: PrlgEnv ()
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addPrelude = do
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pure undefined
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{- primitives -}
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addBi "true" 0 (pure Nothing)
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addBi "fail" 0 backtrack
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addOp $ O.xfx "=" 700
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addProc "=" 2 [[U (LocalRef 0), U (LocalRef 0), NoGoal]]
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{- clauses -}
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addOp $ O.xfy "," 1000
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addOp $ O.xfx ":-" 1200
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horn2 <- findStruct ":-" 2
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--addOp $ O.fx ":-" 1200
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addProc
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"assert"
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1
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[ [ U (Struct horn2)
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, U (LocalRef 0)
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, U (LocalRef 1)
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, Cut
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, Invoke (bi assertClause)
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]
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, [U (LocalRef 0), Invoke (bi assertFact)]
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]
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addBi "retractall" 1 retractall
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addBi "call" 1 call
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addBi "struct" 3 struct
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{- operators -}
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addBi "op" 3 op
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addBi "stash_operators" 0 stashOps
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addBi "pop_operators" 0 popOps
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{- query tools -}
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addBi "print_locals" 0 printLocals
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addBi "prompt_retry" 0 promptRetry'
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addBi "query" 0 (printLocals >> promptRetry)
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{- IO -}
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addBi "write" 1 write
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addBi "writeln" 1 writeln
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addBi "nl" 0 nl
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{- debug -}
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addBi "interpreter_trace" 0 (get >>= liftIO . print >> pure Nothing)
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