From 4884136dad48197db79f3bf84e9edf0704054b2c Mon Sep 17 00:00:00 2001
From: "Niels G. W. Serup" <ngws@metanohi.name>
Date: Sat, 21 Sep 2024 19:47:50 +0200
Subject: [PATCH] Connect SetListElem to outer output list

---
 byg/src/ComputationM.hs | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/byg/src/ComputationM.hs b/byg/src/ComputationM.hs
index 25ee2cd..b566a8b 100644
--- a/byg/src/ComputationM.hs
+++ b/byg/src/ComputationM.hs
@@ -13,7 +13,7 @@ data TypedRun a b where
   FunctionIO :: IsFunctionIO f a b => f -> TypedRun a b
   Inject :: b -> TypedRun () b
   GetListElem :: TypedRun [b] b
-  SetListElem :: TypedRun a ()
+  SetListElem :: TypedRun a [a]
   MapComp :: [DependencyUntyped] -> TypedRun [a] [b]
 
 deriving instance (Show a, Show b) => Show (TypedRun a b)
@@ -44,24 +44,30 @@ evalComputationM' top m = runState (execWriterT (unComputationM m)) top
 evalComputationM :: ComputationM () -> [DependencyUntyped]
 evalComputationM m = fst (evalComputationM' 0 m)
 
-genDependency :: (Show u, Show a) => (Token a -> Dependency u a) -> ComputationM a
-genDependency g = do
+genDependency' :: (Show u, Show a) => (Token a -> ComputationM' (Dependency u a)) -> ComputationM a
+genDependency' f = do
   top <- get
   let top' = top + 1
       target = Token top'
   put top'
-  let result = g target
+  result <- f target
   tell [DependencyUntyped result (show result)]
   pure target
 
+genDependency :: (Show u, Show a) => (Token a -> Dependency u a) -> ComputationM a
+genDependency g = genDependency' (\t -> pure $ g t)
+
 inject :: Show a => a -> ComputationM a
 inject x = genDependency (Dependency NoToken (Inject x))
 
 getListElem :: Show a => Token [a] -> ComputationM a
 getListElem outer = genDependency (Dependency outer GetListElem)
 
-setListElem :: Show a => Token a -> ComputationM ()
-setListElem a = genDependency (Dependency a SetListElem)
+setListElem :: Show a => Token a -> Token [a] -> ComputationM ()
+setListElem a outer = do
+  tell [DependencyUntyped d (show d)]
+  pure NoToken
+  where d = Dependency a SetListElem outer
 
 run :: (Show a, Show b, IsFunction f a b) => f -> Token a -> ComputationM b
 run f input = genDependency (Dependency input (Function f))
@@ -79,13 +85,11 @@ saveFile = runIO SaveFile
 runPandoc = runIO RunPandoc
 
 mapComputationM :: (Show a, Show b) => (Token a -> ComputationM b) -> Token [a] -> ComputationM [b]
-mapComputationM f input = do
+mapComputationM f input = genDependency' $ \target -> do
   top <- get
-  let (res, top') = evalComputationM' top m
+  let (res, top') = evalComputationM' top $ do
+        inp <- getListElem input
+        outp <- f inp
+        setListElem outp target
   put top'
-  genDependency (Dependency input (MapComp res))
-  where m :: ComputationM ()
-        m = do
-          inp <- getListElem input
-          outp <- f inp
-          setListElem outp
+  pure (Dependency input (MapComp res) target)